Project introduction of topographic maps and plans. Technological map of the lesson on the topic “how to make topographic plans and maps.” Image of local items on
2.1. Elements of a topographic map
Topographic map - a detailed large-scale general geographic map reflecting the location and properties of the main natural and socio-economic objects, making it possible to determine their planned and altitude position.
Topographic maps are created primarily based on:
- processing of aerial photographs of the territory;
- by direct measurements and surveys of terrain objects;
- cartographic methods with existing plans and large-scale maps.
Like any other geographical map, a topographic map is a reduced, generalized and figurative symbolic image of the area. It is created according to certain mathematical laws. These laws minimize the distortions that inevitably arise when transferring the surface of the earth's ellipsoid onto a plane, and, at the same time, ensure its maximum accuracy. Studying and drawing maps requires an analytical approach, dividing maps into their constituent elements, the ability to understand the meaning, significance and functions of each element, and see the connection between them.
Map elements (components) include:
- cartographic image;
- mathematical basis;
- legend;
- auxiliary equipment;
- Additional information.
The main element of any geographical map is a cartographic image
- a set of information about natural or socio-economic objects and phenomena, their location, properties, connections, development, etc. Topographic maps depict water bodies, relief, vegetation cover, soils, settlements, routes and means of communication, some industrial, agricultural, cultural, etc. objects.
Mathematical basis
topographic map - a set of elements that determine the mathematical relationship between the real surface of the Earth and a flat cartographic image. It reflects the geometric laws of map construction and the geometric properties of the image, provides the ability to measure coordinates, plot objects according to coordinates, and fairly accurate cartometric determinations of lengths, areas, volumes, angles, etc. Because of this, the map is sometimes called a graphomathematical model of the surrounding world.
The mathematical basis includes:
- map projection;
- coordinate grids (geographical, rectangular and others);
- scale;
- geodetic justification (support points);
- layout, i.e. placement of all map elements within its frame.
Kata scale
can have three types: numerical, graphic (linear) and explanatory caption (named scale). The scale of the map determines the degree of detail with which the cartographic image can be plotted. The scale of maps will be discussed in more detail in Topic 5.
Cartographic grid
is an image of the Earth's degree grid on a map. The type of grid depends on the projection in which the map is compiled. On topographic maps of scales 1:1,000,000 and 1:500,000, meridians look like straight lines converging at a certain point, and parallels look like arcs of eccentric circles. On topographic maps on a larger scale, only two parallels and two meridians (frame) are drawn, limiting the cartographic image. Instead of a cartographic grid, a coordinate (kilometer) grid is applied to large-scale topographic maps, which has a mathematical connection with the Earth’s degree grid.
Card frame
name one or more lines that bound the map.
TO strong points
include: astronomical points, triangulation points, polygonometry points and leveling marks. Control points serve as a geodetic basis for surveying and compiling topographic maps.
2.2. Topographic Map Properties
Topographic maps have the following properties: visibility, measurability, reliability, modernity, geographical correspondence, geometric accuracy, completeness of content.
Among the properties of a topographic map, one should highlight visibility
And measurability
. The clarity of the map provides visual perception of the image earth's surface or its individual sections, their characteristic features and features. Measurability allows you to use a map to obtain quantitative characteristics of the objects depicted on it through measurements.
Visibility and measurability are ensured by:
a mathematically defined relationship between multidimensional environmental objects and their flat cartographic image. This relationship is conveyed using a map projection;
the degree of reduction in the size of depicted objects, which depends on the scale;
highlighting typical terrain features through cartographic generalization;
the use of cartographic (topographic) symbols to depict the earth's surface.
To ensure a high degree of measurability, the map must have sufficient geometric accuracy for specific purposes, which means the correspondence of the location, outline and size of objects on the map and in reality. The smaller the depicted area of the earth's surface while maintaining the dimensions of the map, the higher its geometric accuracy.
The card must be reliable, i.e. the information constituting its contents as of a certain date must be correct, there must also be modern, correspond to the current state of the objects depicted on it.
An important property of a topographic map is completeness content, which includes the volume of information contained in it and its versatility.
2.3. Classification of topographic maps by scale
All domestic topographic maps, depending on their scale, are conditionally divided into three groups:
- Small scale maps (scales from 1:200,000 to 1:1,000,000), as a rule, are used for a general study of the area when developing projects and plans for the development of the national economy; for preliminary design of large engineering structures; as well as to take into account the natural resources of the earth's surface and water spaces.
- Medium-scale maps (1:25,000, 1:50,000 and 1:100,000) are intermediate between small-scale and large-scale. The high accuracy with which all terrain objects are depicted on maps of a given scale allows them to be widely used for various purposes: in the national economy during the construction of various structures; for making calculations; for geological prospecting, land management, etc.
- Large scale cards (1:5,000 and 1:10,000) are widely used in industry and utilities; when conducting detailed geological exploration of mineral deposits; when designing transport hubs and structures. Play an important role large scale maps in military affairs.
2.4. Topographic plan
Topographic plan
- a large-scale drawing depicting in conventional symbols on a plane (on a scale of 1:10,000 and larger) a small section of the earth’s surface, constructed without taking into account the curvature of the level surface and maintaining a constant scale at any point and in all directions. A topographic plan has all the properties of a topographic map and is its special case.
2.5. Topographic map projections
When depicting large areas of the earth's surface, projection is carried out on the level surface of the earth, in relation to which the plumb lines are normal.
Map projection - a method of depicting the surface of the globe on a plane when drawing maps.
It is impossible to unfold a spherical surface on a plane without folds and tears. For this reason, distortions in lengths, angles and areas are inevitable on maps. Only in some projections the equality of angles is maintained, but because of this the lengths and areas are significantly distorted, or the equality of the areas is maintained, but the angles and lengths are significantly distorted.
Projections of topographic maps at a scale of 1:500,000 and larger
Most countries of the world, including Ukraine, use equiangular (conformal) projections to compile topographic maps, preserving the equality of angles between the directions on the map and on the ground. The Swiss, German and Russian mathematician Leonard Euler in 1777 developed the theory of a conformal image of a ball on a plane, and the famous German mathematician Johann Carl Friedrich Gauss in 1822 substantiated the general theory of a conformal image and used conformal plane rectangular coordinates when processing triangulation (method of creating a network of geodetic reference points). Gauss used a double transition: from an ellipsoid to a ball, and then from a ball to a plane. The German surveyor Johannes Heinrich Louis Kruger developed a method for solving conditional equations arising in triangulation and a mathematical apparatus for the conformal projection of an ellipsoid onto a plane, called the Gauss-Kruger projection.
In 1927, the famous Russian geodesist, Professor Nikolai Georgievich Kell, for the first time in the USSR, used the Gauss coordinate system in Kuzbass, and on his initiative, since 1928, this system was adopted as a unified system for the USSR. To calculate Gaussian coordinates in the USSR, they used the formulas of Professor Feodosius Nikolaevich Krasovsky, which are more accurate and convenient than Kruger’s formulas. Therefore, in the USSR there was no reason to give the Gauss projection the name “Gauss-Kruger”.
Geometric entity
This projection can be represented as follows. The entire earth's ellipsoid is divided into zones and maps are drawn up for each zone separately. At the same time, the sizes of the zones are set so that each of them can be expanded into a plane, that is, depicted on a map, practically without noticeable distortions.
To obtain a cartographic grid and compile a map in the Gaussian projection, the surface of the earth's ellipsoid is divided along the meridians into 60 zones of 6° each (Fig. 2.1).
Rice. 2.1. Dividing the Earth's surface into six-degree zones
To imagine how the image of zones is obtained on a plane, let’s imagine a cylinder that touches the axial meridian of one of the zones of the globe (Fig. 2.2).
Rice. 2.2. Projection of the zone onto a cylinder tangent to the earth's ellipsoid along the axial meridian
We will project the zone according to the laws of mathematics onto the side surface of the cylinder so that the property of the image’s equiangularity is preserved (the equality of all angles on the surface of the cylinder to their value on the globe). Then we project all the other zones onto the side surface of the cylinder, one next to the other.
Rice. 2.3. Image of the zones of the earth's ellipsoid
By further cutting the cylinder along the generatrix AA1 or BB1 and turning its side surface into a plane, we obtain an image of the earth's surface on the plane in the form of separate zones (Fig. 2.3).
The axial meridian and equator of each zone are depicted by straight lines perpendicular to each other. All axial meridians of the zones are depicted without distortion of lengths and maintain scale throughout their entire length. The remaining meridians in each zone are depicted in projection as curved lines, so they are longer than the axial meridian, i.e. distorted. All parallels are also depicted as curved lines with some distortion. Distortions of line lengths increase with distance from the axial meridian to the east or west and at the edges of the zone they become greatest, reaching a value of the order of 1/1000 of the line length measured on the map. For example, if along the axial meridian, where there are no distortions, the scale is 500 m per 1 cm, then at the edge of the zone it will be equal to 499.5 m per 1 cm.
It follows that topographic maps have distortions and variable scale. However, these distortions during measurements on the map are very insignificant, and therefore it is believed that the scale of any topographic map for all its sections is constant.
For filming at a scale of 1:25,000 and larger, the use of 3 degrees and even narrower zones is allowed. The overlap of zones is assumed to be 30" to the east and 7" to the west of the axial meridian.
Basic properties of the Gaussian projection:
the axial meridian is depicted without distortion;
the projection of the axial meridian and the projection of the equator are straight lines perpendicular to each other;
the remaining meridians and parallels are depicted as complex curved lines;
the projection ensures that the similarity of small figures is preserved;
the projection ensures the preservation of horizontal angles and directions in the image and terrain.
Projection of a topographic map at a scale of 1:1,000,000
Projection of a topographic map at a scale of 1:1,000,000 - modified polyconic projection, accepted as international. Its main characteristics: the design of the earth's surface covered by a sheet of map is carried out on a separate plane; parallels are depicted as circular arcs, and meridians as straight lines.
To create topographic maps of the United States and the countries of the North Atlantic Alliance, it is used Universal Transverse Mercator Projection, or UTM. In its final form, the UTM system uses 60 zones, each 6 degrees in longitude. Each zone is located from 80º S. up to 84º N The reason for the asymmetry is that 80º S. passes very well in the Southern Ocean, southern South America, Africa and Australia, but it is necessary to rise to 84º N to reach northern Greenland. Zones are counted starting from 180º, with increasing numbers to the west. Together, these zones cover almost the entire planet, excluding only the Arctic Ocean and North and Central Antarctica in the south.
The UTM system does not use a "standard" based on the transverse Mercator projection - the tangent. Instead it is used secant, which has two section lines located approximately 180 kilometers on either side of the central meridian. Map areas in a UTM projection differ from each other not only in the positions of their central meridians and distortion lines, but also in the Earth model they use. The official UTM system definition defines five other spheroids for use in different zones. All UTM zones in the United States are based on the Clarke 1866 spheroid.
Questions and tasks for self-control
- Give definitions: “Topography”, “Geodesy”, “Topographic map”.
- What sciences is topography related to? Explain this connection with examples.
- How are topographic maps created?
- What are the purposes of topographic maps?
- What is the difference between a topographic plan and a topographic map?
- What elements does the map consist of?
- Give a description of each element of the topographic map.
- What do parallels and meridians look like on topographic maps?
- What elements define the mathematical basis of a topographic map? Give a brief description of each element.
- What properties are inherent in topographic maps? Give a brief description of each property.
- On what surface are images of large areas of the Earth projected?
- Define a map projection.
- What distortions can occur when a spherical surface is unfolded on a plane?
- What projections do most countries in the world use to compile topographic maps?
- What is the geometric essence of constructing a Gaussian projection?
- Show in the drawing how a six-degree zone is projected from an earthly ellipsoid onto a cylinder.
- How are the meridians, parallels and equator depicted in the six-degree Gaussian zone?
- How does the nature of distortion change in the six-degree Gaussian zone?
- Can the scale of a topographic map be considered constant?
- In what projection is a topographic map of scale 1:1,000,000 made?
- What map projection is used to create topographic maps in the United States, and how is it different from the Gaussian projection?
The second language of geography is cartographic representation. Even ancient sailors used maps. When planning the expedition, the researchers collected all available cartographic materials for the required area. Upon completion, the results were transferred to paper. This is how the area plan was created. This was the basis for creating new maps. What is a terrain plan and what are its fundamental differences from a geographical map?
terrain?
The very first maps in human history were plans. Now they are used in almost all branches of science and technology: construction cannot be done without them, agriculture, engineering surveys, etc.
A terrain plan is a large-scale image of a section of the earth's surface, the creation of which uses conventional signs. As a rule, these cartographic images are compiled for small areas with areas of up to several square kilometers. In this case, curvature does not affect the image in any way.
How is a plan different from a map?
Often in life we come across both a map and a plan of the area. Geography as a science relies on these cartographic images. But it's not the same thing.
When creating a geographic map, a smaller scale is used (that is, a larger area is covered), the nature of the earth's surface is taken into account, that is, the mathematical law of image construction is used - projection. The most important element geographical maps- degree grid: it is necessary to determine the cardinal directions. Parallels and meridians are often shown as arcs rather than straight lines. Only significant large objects can be plotted on the map. To compile them, a variety of materials are used, including larger-scale maps and satellite images.
A site plan is a more detailed image of a small area. It is built without taking into account the projection, since due to the size of the site, the surface is usually considered flat. The cardinal directions are determined by the directions of the plan frames. Absolutely all terrain elements are subject to display. They are compiled based on materials from large-scale aerial photography or on the ground.
How is the plan made?
To begin with, a point is selected on the site from which the entire area to be mapped is clearly visible. After this, you need to choose the scale of the future plan. Next step- determination of the direction to the north. This can be done using a tablet board and a hand compass. On paper you need to mark the point from which the area will be surveyed, and then draw all the main landmarks (corners of buildings, large trees, pillars).
Then, using special high-precision instruments, azimuths are measured to each point that needs to be reflected on the plan. Each time, azimuths are laid off from the main point, and an auxiliary line is drawn from it, and an angle is marked on the plan. The distance from the main point to the desired points in the area is also measured and transferred to paper.
Then the objects of the site are displayed in the symbols, and the necessary signatures are made.
Throughout the entire area of the cartographic image of the plan, its scale remains unchanged. There are three types of scale:
- Numerical.
- Named.
- Linear.
Numerical is expressed as a fraction, the numerator of which is 1, and the denominator is M. This number M shows the degree of reduction in the size of the image on the plan. Topographic plans have scales of 1:500, 1:1000, 1:2000, 1:5000. For land management work, smaller plan scales are also used - 1:10,000, 1:25,000, 1:50,000. The smaller scale is the one with the larger M number, and vice versa.
It's easier with a named scale - here the length of the lines is expressed verbally. For example, 1 cm is 50 meters. This means that 1 cm of distance on the plan corresponds to 50 m on the ground.
Linear scale - a graph depicted as a straight line segment, which is divided into equal parts. Each such part is signed with a numerical value commensurate with the length of the area.
Conventional signs of the area plan
In order to display any objects or processes on a topographic plan, to indicate their important qualitative or quantitative values, it is necessary to use conventional signs or designations. They give a complete picture of the spatial arrangement of objects, as well as their characteristics and appearance.
There are four types of symbols:
- Large-scale - linear and areal (for example, state squares, roads, bridges).
- Non-scale (well, spring, pillar, tower, etc.).
- Explanatory (signatures of the characteristics of objects, for example, the width of the highway, names of subjects).
They are all reflected in the legend of the plan. Based on the legend, a primary idea of the site is formed.
So, a terrain plan is an image of a small area of the earth's surface on a large scale. It is used in almost all spheres of human activity. Without it, it would be impossible to create topographic maps.
Conducts a range of works to prepare engineering and topographical plans of all scales. Work area: Moscow and the entire Moscow region. Contact us - and you will not regret it!
Drawing up a topographic plan is an integral part of any construction or improvement on a land plot. Of course, you can put a shed on your property without it. Lay out paths and plant trees too. However, starting more complex and voluminous work without a topographic plan is undesirable and often impossible. In this article we will talk specifically about the document itself, as such - why it is needed, what it looks like, etc.
After reading it, you need to understand for yourself whether you really need a topographic plan, and if so, what it is.
What is a topographical plan of a land plot?
We won’t burden you with the official definition, which is needed more for professionals (although they already know the essence). The main thing is to understand the essence of this plan and how it differs from others (for example, a floor plan, etc.). To compile it, you need to carry out. So, a topoplan is a drawing of the elements of the situation, terrain and other objects with their metric and technical characteristics, made in approved symbols. The main feature is its high-altitude component. That is, anywhere on the topographic plan you can determine the height of the object depicted there. In addition to height, on a topoplan you can measure the coordinates and linear dimensions of objects, taking into account, of course. All this data can be obtained either from a paper copy or from a digital one. Usually both options are prepared. Therefore, the topographic plan, in addition to a visual representation of the area, is the starting point for design and modeling.
Topoplan is also often called geological basis and vice versa . Essentially these are two identical concepts with minor reservations. The geobase may contain several topographic plans. That is, this is a collective concept for the entire territory of the object under study. Underground communications must be indicated on the geobasis, in contrast to the topoplan (where the underground is indicated if necessary). But despite the subtleties, these concepts can still be equated.
Who draws up and what is used to make a topographic plan?
Topographical plans are drawn up by surveying engineers. However, now you can’t just graduate from university, get a diploma, buy equipment and start doing topographic surveys. It is also necessary to work as part of an organization that has membership in the relevant SRO (self-regulated organization). This has become mandatory since 2009 and is intended to increase the responsibility and preparedness of surveying engineers. Our company has all the necessary permits for engineering survey activities.
We use advanced equipment () to successfully work in any conditions and areas of geodetic surveys. In particular, electronic roulettes, etc. All devices have been certified and have.
All materials and measurements are processed using specialized licensed software.
Why is a topographic plan needed?
Why does an ordinary land owner or a large construction organization need a topoplan? In essence, this document is a pre-design document for any construction. A topographic plan of a land plot is needed in the following cases:
We have written a full article on this topic - if you are interested, click here.
Documents required for ordering a topographic plan
If the Customer is an individual, it is enough to simply indicate the location of the object (address or cadastral number of the site) and verbally explain the purpose of the work. This will not be enough for legal entities. Still, interaction with a legal entity implies the mandatory drawing up of an agreement, an acceptance certificate and receipt of the following documents from the Customer:
Terms of reference for topographic and geodetic works
-Situation plan of the object
-Available data on previously produced topos graphic works ah, or other documents containing cartographic data about the object
After receiving all the data, our specialists will immediately begin work.
What does a topographic plan look like?
A topographic plan can be either a paper document or a DTM (digital terrain model). At this stage of development of technologies and interactions, a mostly paper version is still needed.
An example of a topographic plan for an ordinary private plot of land presented on the right⇒.
As for the regulatory documents on the methods of conducting topographic surveys and drawing up topographic plans, quite “ancient” SNIPs and GOSTs are also used:
All these documents can be downloaded by clicking on the links.
Accuracy of topographic plans
The above regulatory documents specify in detail the tolerances for determining the horizontal and altitude coordinates of the position of objects on topoplans. But in order not to delve into a large amount of technical and often unnecessary information, we will present the main accuracy parameters for topographic plans at a scale of 1:500 (as the most popular).
The accuracy of a topoplan is not a single and inviolable quantity. You cannot simply say that the angle of the fence is determined with an accuracy of, for example, 0.2 m. It is necessary to indicate regarding what. And here the following quantities appear.
— the average error in the planned position of clear contours of objects should not exceed 0.25 m (undeveloped territory) and 0.35 m (built-up territory) from the nearest points of the geodetic basis (GGS). That is, this is not an absolute value; it consists of errors in the shooting process and errors in starting points. But in essence it is an absolute error in determining a terrain point. After all, starting points are considered infallible when leveling topographic moves.
— the maximum error in the relative position of points of clear contours spaced from each other at a distance of up to 50 meters should not exceed 0.2 m. This is a control of the relative error in the location of terrain points.
— the average error in the planned position of underground communications (identified by a pipe-cable detector) should not exceed 0.35 m from the GGS points.
Topographic maps and plans
topographic map plan relief
1. General information about topographic materials
Topographic materials, which are a reduced-scale projected image of sections of the earth's surface onto a plane, are divided into maps and plans.
A topographic plan is a reduced-scale and similar image on paper of the situation and terrain. A similar image is obtained by orthogonally projecting sections of the earth's surface with a size not exceeding 20 x 20 km onto a horizontal plane. In a reduced form, such an image represents a plan of the area. A situation is a collection of terrain objects, a relief is a collection of various forms of unevenness of the earth's surface. A terrain plan drawn up without a relief image is called situational (contour).
Thus, a plan is a drawing consisting of horizontal positions-segments obtained by orthogonal design of the corresponding sections of the terrain (building structures, roads, hydrographic elements, etc.).
In the form of a plan, a series of construction drawings are compiled that are included in the design and technical documentation necessary for the construction of buildings and structures. Such drawings allow one to view, as it were, reduced-scale images of building structures from above.
An image of large areas of the earth's surface on a plane cannot be obtained without distortion, that is, while maintaining complete similarity. Such areas are orthogonally projected onto the surface of the ellipsoid, and then from the surface of the ellipsoid according to certain mathematical laws called cartographic projections (Gauss-Kruger projection) are transferred to the plane. The resulting reduced image on a plane is called a map.
A topographic map is a reduced, generalized image of significant areas of the Earth's surface constructed according to certain mathematical laws.
Visual perception of the image of the earth's surface, its characteristic features and features is associated with the clarity of plans and maps. Visibility is determined by the identification of typical features of the area that determine its distinctive features, through generalizations - generalization, as well as the use of topographical symbols - a system of symbols - to depict the earth's surface.
Maps and plans must be reliable, that is, the information that constitutes their content as of a certain date must be correct and correspond to the state of the objects depicted on them. An important element of reliability is the completeness of the content, including the required amount of information and its versatility.
According to their purpose, topographic maps and plans are divided into basic and specialized. The main ones include maps and plans for national mapping. These materials are multi-purpose, so they display all the elements of the situation and terrain.
Specialized maps and plans are created to solve specific problems of a particular industry. Thus, road maps contain a more detailed description of the road network. Specialized plans also include survey plans used only during the design and construction of buildings and structures. In addition to plans and maps, topographic materials include terrain profiles, which are a reduced image of a vertical section of the earth's surface along a selected direction. Terrain profiles are the topographic basis for the preparation of design and technical documentation necessary for the construction of underground and above-ground pipelines, roads and other communications.
2.Scale
The degree of reduction of the image on the plan of the contours of the terrain, otherwise the ratio of the length of the line segment on the plan (map) to the corresponding horizontal position of this segment on the terrain is called scale. Scales are divided into numerical and linear.
A numerical scale is a fraction, the numerator of which is one, and the denominator is a number showing how many times lines and objects are reduced when depicting them on a plan (map).
On each sheet of the map or plan he signs it numerical scale in the form: 1:1000; 1:5000; 1:10,000; 1:25000, etc.
Linear scale is a graphic expression of a numerical scale (Fig. 9). To construct a linear scale, draw a straight line and mark the same distance in centimeters on it several times, called the base of the scale. The base is usually taken two centimeters long. The length of the line on the ground, corresponding to the base of the linear scale, is signed from left to right as it increases, and the first left base is divided into 10 more parts. The practical accuracy of the linear scale is ±0.5 mm, which corresponds to 0.02-0.03 bases of the scale.
For more accurate graphic work on the plan, use a transverse scale, which allows you to measure segments with an accuracy of 0.01 of its base.
The transverse scale is a graph based on proportional division (Fig. 10); to construct a scale on a straight line, the bases of the scale are laid off several times; perpendiculars are drawn from the division points; The first left base is divided by 10
Fig.9. Linear and numerical scales on topographic maps
parts, and 10 equal parts are also laid on perpendiculars and lines parallel to the base are drawn through the points of deposition, as shown in Fig. 10. From the similarity of triangles BDE and Bde it follows that de/DE = Bd/BD or de= Bd∙DE/BO, but DE = AB/10, Bd= BD/10. Substituting the values of DE and Bd, we get de= AB/100, i.e. e. smallest division transverse scale equal to a hundredth of a base. Using a scale with a base of 10 mm, you can determine the lengths of segments with an accuracy of 0.1 mm. The use of any scale, even transverse, cannot provide accuracy above a certain limit, depending on the properties of the human eye. With the naked eye, from a normal vision distance (25cm), you can estimate a size on the plan that does not exceed 0.1mm (details of terrain objects smaller than 0.1mm cannot be depicted on the plan). Scale accuracy is characterized by a horizontal distance on the ground corresponding to 0.1 mm on the plan. For example, for plans drawn on a scale of 1:500, 1:1000, 1:2000, the scale accuracy is respectively 0.05, 0.1, 0.2 m. The accuracy of the scale determines the degree of generalization (generalization) of details that can be depicted on a plan (map) of a particular scale.
3.Uword marks on plans and maps
Topographic maps and plans depict various terrain features: contours settlements, gardens, vegetable gardens, lakes, rivers, road lines, power transmission lines. The collection of these objects is called a situation. The situation is depicted using conventional signs.
Conventional signs, mandatory for all institutions and organizations that compile topographic maps and plans, are established by the Federal Service of Geodesy and Cartography of Russia (Roscartography) and are published either separately for each scale or for a group of scales. Although the number of conventional signs is large (about 400), they are easy to remember, since they superficially resemble the appearance and character of the depicted objects.
Conventional signs are divided into five groups: area, linear, non-scale, explanatory, special.
Area symbols (Fig. 11, a) are used to fill the areas of objects (for example: arable lands, forests, lakes, meadows); they consist of a sign of the boundary of an object (a dotted line or a thin solid line) and images or conventional coloring that fill it; for example, on conventional sign 1 shows a birch forest; the numbers (20/0.18)∙4 characterize the tree stand: the numerator is the average height, the denominator is the average trunk thickness, 4 is the average distance between trees.
Linear symbols are objects of a linear nature (roads, rivers, communication lines, power transmission lines), the length of which is expressed on a given scale. On conventional images various characteristics of objects are given; for example, on highway 7 it is shown, m: the width of the roadway is 8, the width of the entire road is 12; on the railway 8, m: +1.8 - embankment height, -2.9 - excavation depth.
Out-of-scale symbols are used to depict objects whose dimensions are not displayed at a given scale of a map or plan (bridges, kilometer posts, wells, geodetic points).
As a rule, off-scale signs determine the location of objects, but their size cannot be judged from them. The signs give various characteristics, for example: length 17 and width 3 m of wooden bridge 12, mark 393.500 points of geodetic network 16.
Explanatory symbols are digital and alphabetic inscriptions that characterize objects, for example: the depth and speed of river flows, load capacity and width of bridges, forest species, average height and thickness of trees, width of highways. They are placed on the main areal, linear, and non-scale signs.
Special symbols (Fig. 11, d) are established by the relevant departments of the national economy; they are used to draw up specialized maps and plans of this industry, for example, signs for survey plans of oil and gas fields - oil field structures and installations, wells, field pipelines.
To give a map or plan greater clarity, colors are used to depict various elements: for rivers, lakes, canals, wetlands - blue; forests and gardens - green; highways - red; improved dirt roads - orange.
Everything else is given in black. On survey plans, underground communications (pipelines, cables) are colored.
4.Pterrain relief and methods of depicting it. Steepness of slopes
The terrain is a collection of irregularities on the earth's surface.
Depending on the nature of the relief, the terrain is divided into flat, hilly and mountainous. Flat terrain has weakly defined forms or almost no unevenness; hilly is characterized by alternating relatively small elevations and decreases; mountainous is an alternation of elevations more than 500m above sea level, separated by valleys.
Of the variety of landforms, the most characteristic ones can be identified (Fig. 12).
A mountain (hill, height, hill) is a cone-shaped relief form rising above the surrounding area, the highest point of which is called the summit (3, 7, 12). The top in the form of a platform is called a plateau, the top of a pointed shape is called a peak. The side surface of the mountain consists of slopes, the line where they merge with the surrounding terrain is the sole, or base, of the mountain.
Rice. 12. Characteristic forms of relief: 1 - hollow; 2 - ridge; 3,7,12 - vertices; 4 - watershed; 5.9 - saddles; 6 - thalweg; 8 - river; 10 - break; 11 - terrace
A basin or depression is a bowl-shaped depression. The lowest point of the basin is the bottom. Its lateral surface consists of slopes, the line where they merge with the surrounding area is called the edge.
Ridge2 is a hill that gradually decreases in one direction and has two steep slopes called slopes. The axis of the ridge between the two slopes is called the watershed line or watershed 4.
Hollow 1 is an elongated depression in the terrain, gradually descending in one direction. The axis of the hollow between two slopes is called the drainage line or thalweg 6. The varieties of the hollow are: valley - a wide hollow with gentle slopes, and also a ravine - a narrow hollow with almost vertical slopes (cliffs 10). The initial stage of a ravine is a ravine. A ravine overgrown with grass and bushes is called a ravine. Sites sometimes located along the slopes of hollows, looking like a ledge or step with an almost horizontal surface, are called terraces 11.
Saddles 5, 9 are low parts of the terrain between two peaks. Roads often pass through saddles in the mountains; in this case the saddle is called a pass.
The top of the mountain, the bottom of the basin and the lowest point of the saddle are characteristic points of the relief. The watershed and thalweg represent characteristic relief lines. Characteristic points and lines of relief make it easier to recognize its individual forms on the ground and depict them on a map and plan.
The method of depicting the relief on maps and plans should make it possible to judge the direction and steepness of slopes, as well as determine the marks of terrain points. At the same time, it must be visual. Various methods of depicting the relief are known: perspective, shading with lines of different thicknesses, colored washing (mountains - brown, hollows - green), horizontal lines. The most advanced methods from an engineering point of view for depicting the relief are horizontal lines in combination with a signature of the marks of characteristic points (Fig. 13) and digital.
A horizontal line is a line on a map connecting points of equal heights. If we imagine a section of the Earth's surface by a horizontal (level) surface P0, then the line of intersection of these surfaces, orthogonally projected onto a plane and reduced to a size on the scale of a map or plan, will be horizontal. If the surface P 0 is located at a height H from the leveled surface, taken as the origin of absolute heights, then any point on this horizontal line will have an absolute elevation equal to H. An image in the contour lines of the relief of the entire area of the terrain can be obtained by cutting the surface of this area with a series of horizontal planes Р 1, Р 2,… Р n, located at the same distance from each other. As a result, contour lines with marks H + h, H + 2h, etc. are obtained on the map.
The distance h between cutting horizontal planes is called the height of the relief section. Its value is indicated on the map or plan under the linear scale. Depending on the scale of the map and the nature of the depicted relief, the height of the section is different.
The distance between contour lines on a map or plan is called elevation. The greater the laying, the less steep the slope on the ground, and vice versa.
Rice. 13.Image of the terrain with contours
Property of contours: contours never intersect, with the exception of an overhanging cliff, natural and artificial craters, narrow ravines, steep cliffs, which are not displayed by contours, but are indicated by conventional signs; horizontal lines are continuous closed lines that can only end at the border of a plan or map; the denser the horizontal lines, the steeper the relief of the depicted area, and vice versa.
The main forms of relief are depicted by horizontal lines as follows (Fig. 14).
The images of the mountain and the basin (see Fig. 14, a, b), as well as the ridge and hollow (see Fig. 14, c, d), are similar to each other. To distinguish them from each other, the direction of the slope is indicated at the horizontal. On some horizontal lines, markings of characteristic points are signed, and so that the top of the numbers is directed in the direction of increasing the slope.
Rice. 14. Depiction of characteristic relief forms by horizontal lines: a - mountain; b - basin; c - ridge; g - hollow; d - saddle; 1 - top; 2 - bottom; 3 - watershed; 4 - thalweg
If, at a given height of the relief section, some of its characteristic features cannot be expressed, then additional half and a quarter horizontal lines are drawn, respectively, through half or a quarter of the accepted height of the relief section. Additional horizontal lines are shown with dotted lines.
To make contour lines on the map easier to read, some of them are thickened. With a section height of 1, 5, 10, and 20 m, every fifth horizontal line is thickened with marks that are multiples of 5, 10, 25, 50 m, respectively. With a section height of 2.5 m, every fourth horizontal line is thickened with marks that are multiples of 10 m.
The steepness of the slopes. The steepness of the slope can be judged by the size of the deposits on the map. The smaller the laying (distance between horizontal lines), the steeper the slope. To characterize the steepness of the slope on the ground, the inclination angle ν is used. The vertical angle of inclination is the angle between the terrain line and its horizontal position. The angle ν can vary from 0º for horizontal lines and up to ± 90º for vertical lines. The greater the angle of inclination, the steeper the slope.
Another characteristic of steepness is slope. The slope of the terrain line is the ratio of the elevation to the horizontal distance = h/d = tgν.
From the formula it follows that the slope is a dimensionless quantity. It is expressed as a percentage % (hundredths) or in ppm ‰ (thousands).Back<../Октябрь/Бесплатные/геодезия/новые%20методички/Учебное%20пособие%20по%20инженерной%20геодезии.wbk>
5. Classification and nomenclature of plans and maps
Maps and plans are classified mainly by scale and purpose.
By scale, maps are divided into small-, medium- and large-scale. Small-scale maps smaller than 1:1000000 are overview maps and are practically not used in geodesy; medium-scale (survey-topographic) maps at scales 1:1000000, 1:500000, 1:300000 and 1:200000; large-scale (topographic) - scales 1:100000, 1:50000, 1:25000, 1:10000. The scale series adopted in the Russian Federation ends with topographic plans of scales 1:5000, 1:2000, 1:1000, 1:500. In construction, plans are sometimes drawn up to scale
:200, 1:100 and 1:50.
According to their purpose, topographic maps and plans are divided into basic and specialized. The main ones include maps and plans for national mapping. These are multi-purpose maps, so they display all the elements of the terrain.
Rice. 15. Dividing a map of scale: 1:100000 into sheets of maps with scales of 1:50000, 1:25000 and 1:10000
The nomenclature is based on the international layout of map sheets at a scale of 1:1000000. Map sheets of this scale are limited by meridians and parallels in latitude 4º, longitude 6º. Each sheet occupies only its own place, being designated by a capital Latin letter, which defines the horizontal belt, and an Arabic numeral, which defines the number of the vertical column. For example, a sheet of a map at a scale of 1:1000000, on which Moscow is located, has the nomenclature N-37.
The layout of maps of larger scales is obtained by sequentially dividing a sheet of a map at a scale of 1:1000000. One sheet of a map of scale 1:1,000,000 corresponds to: four sheets of scale 1:500,000, designated by the letters A, B, C, D (the nomenclature of these sheets is, for example, N-37-A); nine sheets of scale 1:300000, designated by Roman numerals I, II, ..., IX (for example, IX -N-37); 36 sheets of scale 1:200000, also designated by Roman numerals (for example, N-37-I); 144 sheets of scale 1:100000, designated by Arabic numerals from 1 to 144 (for example, N-37-144).
One sheet of a 1:100,000 map corresponds to four sheets of a map of scale 1: 50,000, designated by the letters A, B, C, D; the nomenclature of sheets of this map looks like, for example, N-37-144-A. One sheet of a 1:50000 map corresponds to four sheets of a map at a scale of 1:25000, designated by the letters a, b, c, d, for example N-37-144-A-a. One sheet of a 1:25000 map corresponds to four sheets of a 1:10000 map, designated by the numbers 1, 2, 3, 4, for example N-37-144-A-a-l.
Figure 15 shows the numbering of sheets of maps of scales 1:50000 ... 1:10000, making up a sheet of map of scale 1:100000.
Layout of sheets of large-scale plans is done in two ways. For surveying and drawing up plans over an area of more than 20 km 2, a scale map sheet is used as the basis for the layout
:100000, which is divided into 256 parts for a scale of 1:5000, and each sheet of scale 1:5000 is divided into nine parts for plans of a scale of 1:2000. In this case, the nomenclature of a sheet at a scale of 1:5000 looks like, for example, N-37-144(256), and for a scale of 1:2000 - N-37-144(256-I).
For site plans with an area of less than 20 km2, a rectangular layout is used (Fig. 16) for a scale of 1:5000 with sheet frames of 40x40 cm, and for scales 1:2000...1:500 - 50x50 cm. The scale sheet is taken as the basis for the rectangular layout 1:5000, denoted by Arabic numerals (for example, 1). A plan sheet on a scale of 1:5000 corresponds to four sheets on a scale of 1:2000, designated by the letters A, B, C, D. A plan sheet on a scale of 1:2000 corresponds to four sheets on a scale of 1:1000, designated by Roman numerals, and 16 sheets in scale 1:500, indicated by Arabic numerals.
Rice. 16. Rectangular layout of the plan sheet
The plans of scales 1:2000, 1:1000, 1:500 shown in the figure have the nomenclature 2-G, 3-B-IV, 4-B-16, respectively.
6. Solving problems on plans and maps
The geographic coordinates of point A (Fig. 17), latitude φ and longitude λ are determined on a plan or map, using the minute scales of the trapezoid frames.
To determine latitude, a line is drawn through point A parallel to the trapezoid frames and readings are taken at the intersections with the scale of the western or eastern frame.
Similarly, to determine longitude, a meridian is drawn through point A and readings are taken on the scales of the northern or southern frame.
Rice. 17. Determination of the coordinates of a point on a topographic plan: 1 - vertical kilometer line; 2 - digital designation of horizontal grid lines; 3 - digital designations of vertical grid lines; 4 - inner frame; 5 - frame with minutes; 6 - horizontal kilometer line
In the example given, latitude φ = 54º58.6′ s. latitude, longitude λ = 37º31.0′ e. d.
The rectangular coordinates X A and Y A of point A are determined relative to the kilometer grid lines.
To do this, measure the distance ∆X and ∆Y along perpendiculars to the nearest kilometer lines with coordinates X 0 and Y 0 and find
X A = X 0 + ∆X
Y A = Y 0 + ∆Y.
Distances between points on plans and maps are determined using a linear or transverse scale, curved segments are determined using a curvimeter device.
To measure the directional angle of a line, a line is drawn through its starting point parallel to the abscissa axis, and the directional angle is measured directly at this point. You can also extend the line until it intersects the nearest grid ordinate line and measure the directional angle at the intersection point.
To directly measure the true azimuth of a line, a meridian is drawn through its starting point (parallel to the eastern or western frame of the trapezoid) and the azimuth is measured relative to it.
Since it is difficult to draw the meridian, you can first determine the directional angle of the line, and then use the given formulas to calculate the true and magnetic azimuths.
Determining the steepness of the slope. The steepness of the slope is characterized by the angle of inclination ν, which is formed by a terrain line, for example AB, with a horizontal plane P (Fig. 18).
tan ν = h/a, (15.1)
where h is the height of the relief section; a - mortgage.
Knowing the tangent, use tables of values of trigonometric functions or use a microcalculator to find the value of the angle of inclination.
The steepness of the slope is also characterized by the slope of the line
i= tanν. (15.2)
The slope of the line is measured in percent or ppm (‰), i.e. thousandths of a unit.
Rice. 18. Scheme for determining the steepness of the slope
As a rule, when working with a map or plan, the angle of inclination or slope of the slope is determined using graphs (Fig. 19) with the scale of the locations.
Rice. 19. Layout graphs for the plan at a scale of 1:1000 with a relief section height of h = 1.0m a - for inclination angles; b - slopes.
To do this, take the position between two horizontal lines along a given slope from the plan, then use the graph to find the place where the distance between the curve and the horizontal line is equal to this position. For the ordinate found in this way, read the value ν or i along a horizontal straight line (marked with asterisks on the graphs above: ν = 2.5º; i = 0.05 = 5% = 50‰).
Example 1. Determine the angle of inclination and slope of the terrain between horizontal lines on a scale plan of 1:1000, if the elevation is 20 mm, the height of the relief section is h = 1.0 m. On the ground, the laying will correspond to a segment length of 20mm ∙ 1000 = 20000mm = 20m. According to formulas (15.1) and (15.2) tanν = i = 1:20 = 0.05. Therefore, i = 5% = 50‰, and ν = 2.9º.
Determination of elevations of terrain points. If a point is located on the horizontal, its elevation is equal to the horizontal elevation. When point K (Fig. 20) is located between horizontal lines with different heights, its mark H K is determined by interpolation (finding intermediate values of quantities) “by eye” between the marks of these horizontal lines.
Interpolation consists in determining the coefficient of proportionality of the distance d from the determined point to the smaller horizontal line N MG. To the value of location a, i.e. ratio d/a, and multiplying it by the value of the height of the relief section h.
Example 2. Marking point K, located between the horizontal lines with marks 150 and 152.5 m (Fig. 20, a),
H K = H M. G + (d/a)h = 150 + 0.4 ∙ 2.5 = 151m.
Rice. 20. Determination of horizontal elevations of points: a...d - diagrams with a section height h = 2.5 m
If the point being determined is located between horizontal lines of the same name - on a saddle (Fig. 20, b) or inside a closed horizontal line - on a hill or basin (Fig. 20, c, d), then its mark can only be determined approximately, assuming that it is greater than or less than the height of this horizontal line by 0.5h. For example, in the figure for the saddle the elevation of the Kravna point is 138.8 m, for the hill - 128.8 m, for the basin - 126.2 m.
Drawing a line of a given maximum slope on the map (Fig. 21). Between points A and B given on the map, it is required to draw the shortest line so that not a single segment has a slope greater than the specified limit i pr.
Rice. 21. Scheme of drawing a line of a given maximum slope on the map
The easiest way to solve the problem is by using the scale for slopes. Having taken along it with a compass solution the position apr, corresponding to the slope, sequentially mark points 1...7 all horizontals from point A to point B. If the compass solution is less than the distance between the horizontals, then the line is drawn in the shortest direction. By connecting all the points, a line with a given maximum slope is obtained. If there is no scale of location, then the location of a pr can be calculated using the formula a pr = h/(i pr M), where M is the denominator of the numerical scale of the map.
Rice. 22. Scheme for constructing a profile in a given direction: a - direction according to the map; b - profile in direction
Construction of a terrain profile in the direction specified on the map. Let's look at building a profile using a specific example (Fig. 22). Let it be necessary to construct a terrain profile along line AB. To do this, line AB is transferred on the map scale to paper and points 1, 2, 4, 5, 7, 9 are marked on it, at which it intersects the horizontal lines, as well as characteristic relief points (3, 6, 8). Line AB serves as the base of the profile. Point marks taken from the map are laid on perpendiculars (ordinates) to the base of the profile on a scale 10 times greater than the horizontal scale. The resulting points are connected by a smooth line. Usually, the profile ordinates are reduced by the same amount, i.e., the profile is built not from zero heights, but from the conventional horizon UG (in Fig. 22, a height of 100 m is taken as the conventional horizon).
Using a profile, you can set the mutual visibility between two points, for which you need to connect them with a straight line. If you build profiles from one point in several directions, you can plot on a map or plan areas of the terrain that are not visible from this point. Such areas are called visibility fields.
Calculation of volumes (Fig. 23). Using a map with contour lines, you can calculate the volumes of a mountain and a basin, depicted by a system of contour lines enclosed within a small area. To do this, landforms are divided into parts bounded by two adjacent horizontal lines. Each such part can be approximately taken as a truncated cone, the volume of which is V = (1/2)(Si+ Si+I)h c , where Si and Si+I are the areas limited on the map by the lower and upper horizontal lines, which are the bases of the truncated cone; h c - height of the relief section; i = 1, 2, ..., k - current number of the truncated cone.
Areas S are measured with a planimeter (mechanical or electronic).
The approximate area of a plot can be determined by dividing it into many regular mathematical figures (trapezoids, triangles, etc.) and summing it by area. The volume V in the uppermost part is calculated as the volume of a cone, the base area of which is equal to S B and the height h is the difference between the elevations of the top point t and the horizontal line limiting the base of the cone:
Rice. 23. Scheme for determining volume
V B = (S B / 3)∙h
If the mark of point t on the map is not marked, then h = h c /2 is taken. The total volume is calculated as the sum of the volumes of the individual parts:
V 1 + V 2 + ... + V k + V B,
where k is the number of parts.
Measuring areas on maps and plans is required to solve various engineering and economic problems.
There are three known ways to measure areas on maps: graphical, mechanical and analytical.
The graphical method includes the method of dividing the measured area into the simplest geometric figures and a method based on using a palette.
In the first case, the area to be measured is divided into simple geometric figures (Fig. 24.1), the area of each of which is calculated using simple geometric formulas and the total area of the figure is determined as the sum of the areas of geometric partial figures:
Rice. 24. Graphic methods for measuring the area of a figure on a map or plan
In the second case, the area is covered with a palette consisting of squares (see Fig. 24.2), each of which is a unit of area measurement. The areas of incomplete figures are calculated by eye. The palette is made of transparent materials.
If the area is limited by broken lines, then its area is determined by dividing it into geometric shapes. With curved boundaries, it is easier to determine the area using a palette.
The mechanical method involves calculating areas on maps and plans using a polar planimeter.
The polar planimeter consists of two levers, pole 1 and bypass 4, pivotally connected to each other (Fig. 25a).
Rice. 25. Polar planimeter: a - appearance; b - counting by the counting mechanism
At the end of the pole lever there is a weight with a needle - pole 2, the bypass lever at one end has a counting mechanism 5, at the other - bypass index 3. The bypass lever has a variable length. The counting mechanism (Fig. 25, b) consists of a dial 6, a counting drum 7 and a vernier 8. One division on the dial corresponds to the revolution of the counting drum. The drum is divided into 100 divisions. Tenths of the small division of the drum are estimated by the vernier. The full reading on the planimeter is expressed as a four-digit number: the first digit is counted on the dial, the second and third - on the counting drum, the fourth - on the vernier. In Fig. 25, b the counting on the counting mechanism is equal to 3682.
Rice. 26. Analytical method for measuring area
Having set the bypass index at the starting point of the contour of the measured figure, take count a using the counting mechanism, then use the bypass index to move clockwise along the contour to the starting point and take count b. The difference in readings b - a represents the area of the figure in planimeter divisions. Each planimeter division corresponds to an area on the ground or plan, called the planimeter division value P. Then the area of the outlined figure is determined by the formula
S = P(b - a)
To determine the division price of a planimeter, measure a figure whose area is known or which can be determined with great accuracy. Such a figure on topographic plans and maps is a square formed by the lines of a coordinate grid. The division price of the planimeter P is calculated using the formula
P = S out / (b - a),
where S is the known area of the figure; (b - a) - difference of samples c. starting point when tracing a figure with a known area.
The analytical method consists of calculating the area based on the results of measurements of angles and lines on the ground. Based on the measurement results, the X, Y coordinates of the vertices are calculated. The area P of polygon 1-2-3-4 (Fig. 26) can be expressed through the areas of trapezoids
P = P 1′-1-2-2′ + P 2′-2-3-3′ - P 1′-1-4-4′ - P 4′-4-3-3′ = 0.5( (x 1 + x 2)(y 2 - y 1) + (x 2 + x 3)(y 3 - y 2) -(x 1 + x 4)(y 4 - y 1) - (x 4 + x 3)(y 3 - y 4)).
Having made the transformations, we obtain two equivalent formulas for determining the double area of a polygon
2P = x 1 (y 2 - y 4) + x 2 (y 3 - y 1) + x 3 (y 4 - y 2) + x 4 (y 1 - y 3);
P = y 1 (x 4 - x 2) + y 2 (x 1 - x 3) + y 3 (x 2 - x 4) + y 4 (x 3 - x 1).
Calculations can be easily performed on any microcalculator.
The accuracy of determining areas analytically depends on the accuracy of the measured values.
7.Idigital image of the earth's surface
The development of computer technology and the emergence of automatic drawing devices (plotters) led to the creation of automated systems for solving various engineering problems related to the design and construction of structures. Some of these problems are solved using topographic plans and maps. In this regard, there is a need to present and store information about the topography of the area in a digital form convenient for the use of computers.
In computer memory, digital terrain data can best be represented in the form of x, y, H coordinates of a certain set of points on the earth's surface. Such a set of points with their coordinates forms a digital terrain model (DTM).
All elements of the situation are specified by the x and y coordinates of the points that determine the position of objects and terrain contours. A digital elevation model characterizes the topographic surface of the area. It is determined by a certain set of points with coordinates x, y, H, selected on the earth's surface so as to sufficiently reflect the nature of the relief.
Rice. 27. Diagram of the location of points of the digital model in characteristic places of the relief and on horizontal lines
Due to the variety of relief forms, it is quite difficult to describe it in detail in digital form, therefore, depending on the problem being solved and the nature of the relief, various methods of compiling digital models are used. For example, a DEM may take the form of a table of coordinate values x, y, H at the vertices of a grid of squares or regular triangles, evenly distributed over the entire area of the terrain. The distance between the peaks is selected depending on the shape of the relief and the problem being solved. The model can also be specified in the form of a table of coordinates of points located in characteristic places (inflections) of the relief (watersheds, thalwegs, etc.) or on horizontal lines (Fig. 27). Using the coordinate values of the points of the digital relief model for a more detailed description on a computer using a special program, the height of any point on the terrain is determined.
Literature
Basova I.A., Razumov O.S. Satellite methods in cadastral and land management works. - Tula, Tula State University Publishing House, 2007.
Budenkov N.A., Nekhoroshkov P.A. Engineering geodesy course. - M.: Publishing house MGUL, 2008.
Budenkov N.A., Shchekova O.G. The engineering geodesy. - Yoshkar-Ola, MarSTU, 2007.
Bulgakov N.P., Ryvina E.M., Fedotov G.A. Applied geodesy. - M.: Nedra, 2007.
GOST 22268-76 Geodesy. Terms and Definitions
Engineering geodesy in construction./Ed. O.S. Razumov. - M.: Higher School, 2008.
The engineering geodesy. / Ed. prof. D.Sh.Mikhelev. - M.: Higher School, 2009.
Kuleshov D.A., Strelnikov G.E. Engineering geodesy for builders. - M.: Nedra, 2007.
Manukhov V.F., Tyuryakhin A.S. Engineering geodesy - Saransk, Mordovia State University, 2008.
Manukhov V.F., Tyuryakhin A.S. Glossary of satellite geodesy terms - Saransk, Mordovian State University, 2008.
TRAINING AND METHODOLOGICAL CENTER
METHODOLOGICAL DEVELOPMENT
To conduct classes on initial training of rescuers
(topography)
TOPIC No. 2 “Topographic maps, terrain diagrams and plans”
Chelyabinsk
LEARNING OBJECTIVES: Study with students the scales of topographic maps,
give basic concepts of map orientation and topography
graphic symbols used on the map.
M E S T O: Cool.
TIME: 2 hours.
M E T O D: Practical lesson.
STUDY QUESTIONS AND TIME RECORDING
Introductory part - 5 min
Study question 1: Drawing up a plan and diagrams.- 45 min
2nd educational question: Orientation on the map. - 30 min
Conclusion: - 10 min.
L I T E R A T U R A:
1. Textbook “Military topography” for cadets of educational units.
2. Officer's Handbook on Military Topography.
H O D A N I T I O N :
Check the availability of listeners,
Announce the topic, purpose, educational questions.
INTRODUCTORY PART:
Rescuers' actions take place on the ground or are closely related to it. The knowledge, teachings and skills acquired during the study of topography are of great practical importance in the activities of rescuers.
Knowledge of ways to study terrain, skills in orientation and movement on it in various conditions, day, night, with limited visibility, contribute to the correct use of favorable terrain properties to achieve success, help to quickly and confidently navigate and maintain a given direction when moving and maneuvering. The ability to use a topographic map makes it possible to study and evaluate the terrain in advance, and prepare the necessary data for the march.
Using the map, it is easier to make the most appropriate decision and assign tasks to subordinates.
1st educational question: Classification of topographic maps, local maps
sti and plans. Conventional signs.
TOPOGRAPHIC MAP - a basic graphic document of an area containing an accurate, detailed and visual representation local items and relief. On topographic maps, local objects are depicted by generally accepted symbols, and the relief is depicted by contour lines.
Topographic maps are intended for the work of rescuers in preparing, organizing and conducting work. Using them, they study and evaluate the terrain, solve various calculation problems related to determining distances, angles and areas, heights, elevations and mutual visibility of terrain points, steepness and types of slopes, etc. They are planning a march and preparing
data for movement in azimuths.
The completeness, detail and accuracy of the depiction of the area on the map depend primarily on its scale.
Map scale shows how many times the length of a line on a map is less than its corresponding length on the ground. It is expressed as a ratio of two numbers. For example, a scale of 1:50,000 means that all terrain lines are depicted on the map with a reduction of 50,000 times, i.e. 1 cm on the map corresponds to 50,000 cm (or 50 m) on the ground.
The scale is indicated under the bottom side of the map frame in digital terms (numerical scale) and in the form of a straight line (linear scale), on the segments of which the corresponding distances on the ground are labeled. The scale value is also indicated here - the distance in meters (or kilometers) on the ground, corresponding to one centimeter on the map. It is useful to remember the rule: if you cross out the last two zeros on the right side of the ratio, then the remaining number will show how many meters on the ground correspond to 1 cm on the map, i.e. scale value.
When comparing several scales, the larger one will be the one with the smaller number on the right side of the ratio. Let us assume that for the same area of terrain there are maps of scales 1:25,000, 1:50,000 and 1:100,000. Of these, the scale of 1:25,000 will be the largest, and the scale of 1:100,000 will be the smallest.
A scale range has been established for topographic maps.
TOPOGRAPHICAL PLANS.
Large settlements and other important facilities may be created topographic plans. They are a type of topographic maps and differ from them in that they are published in separate sheets, the dimensions of which are determined by the boundaries of the depicted area of the area (settlement, object). The plans have some design features.
Most often, plans are drawn up at scales of 1:10,000 - 1:25,000, which make it possible to show in great detail the nature of the depicted object and provide detailed information about the qualitative and quantitative characteristics of local objects and relief details located both on the object itself and on the nearest approaches to him. According to the depicted area (object) of the area, the name of the plan is signed, for example, Plan of Zavodskaya Station, Plan of Camps, etc.
For ease of use and greater clarity, city plans highlight prominent buildings with special symbols and colors, and city transport lines (metro, tram) are shown. To facilitate the purpose of the indication, the plan provides a conventional numbering of blocks and some local items, and a brief legend, a list of prominent buildings and an alphabetical street index are placed in the margins or on the back of the plan. A sample part of the city plan is given in Appendix 4.
Area diagram – a drawing on which the most characteristic local objects, as well as individual relief elements, are depicted with approximate accuracy.
Local objects are depicted on the diagram by topographical symbols, hills and depressions (heights, basins) are represented by several closed horizontal lines, and ridges and hollows are represented by fragments of horizontal lines that outline the configuration of these relief forms. At the same time, in order to speed up the work, the symbols of some local objects are simplified.
Drawing up terrain maps using eye survey techniques. To carry out eye survey, you need to have a compass, a sight line, a pencil, an eraser and a blank sheet of paper mounted on a rigid base (a piece of cardboard, plywood, etc.) In some cases, when the survey needs to be carried out quickly and does not require special care , it can be done with only a pencil and paper.
Let's consider some eye survey techniques used in drawing up terrain diagrams.
Shooting from one standing point used when the drawing requires showing a small area of terrain located directly around the standing point or in a given sector. In this case, shooting is performed using the circular sighting method in the following sequence.
A standing point is placed on a sheet of paper so that the area to be removed fits on this sheet. For example, if we are standing in the center of the area being photographed, then the standing point should be marked in the center of the sheet of paper, if
If we stand in one of the corners or on the edge of the area, then a dot on the paper should be placed in the corresponding corner or on the edge of the sheet of paper. Then, having oriented the sheet of paper relative to the area being filmed, they fix it on some object (stump, bridge railing, trench parapet) and, without disturbing the position of the sheet, carry out the survey.
If you have to work while holding a sheet of paper in your hand, then first draw a north-south direction on it. To do this, orienting a sheet of paper relative to the area being photographed, place a compass on it, release the needle brake and, when the needle calms down, draw a line parallel to the compass needle.
In the future, make sure that the direction of the compass needle exactly coincides with the drawn north-south line. When it is necessary to orient the drawing again, for example after a break in work, a compass is placed on it so that the divisions are 0 degrees (O) and 180 degrees. (S) coincide with the drawn north-south direction, then turn the drawing until the northern end of the compass needle is opposite the 0 degree division (N). In this position, the drawing will be oriented and you can continue working on it.
In order to put this or that object on the drawing, after orienting the sheet, you need to attach a ruler (pencil) to the standing point indicated on it and turn it around the point until the direction of the ruler coincides with the direction of the object. With this position of the ruler, draw a straight line along it from the standing point, this line will be the direction in which the object being drawn on the diagram is located. So they sequentially point the ruler at all other objects and draw directions for each of them.
Then the distances to the objects are determined and they are laid out in the appropriate directions from the standing point on the scale of the drawing or approximately, maintaining the approximate ratio of these distances in the drawing and on
Localities. The points obtained in the directions will indicate the location of objects in the drawing. In the places of the points, conventional signs of the applied objects are drawn, in relation to which the remaining details of the terrain, located directly near the point of standing, as well as those located between the applied landmarks or near them, are visually applied. Individual trees, bushes near the road, a section of an improved dirt road, ruins, holes, etc. are marked in this way on the terrain map.
Shooting from multiple vantage points performed when it is necessary to show a relatively large area of terrain.
In this case, local objects are marked on the drawing with serifs, by measuring distances, along the alignment, by the method of circular sighting, by the method of perpendiculars.
When preparing for shooting, it is necessary to secure the sheet of paper on which the shooting will be carried out on a solid base (tablet). A compass is attached to the same base so that the north-south line on the compass scale is approximately parallel to one of the sides of the tablet or sheet of paper.
For the speed and convenience of plotting distances measured in steps, it is necessary to make a step scale. This scale is built on a separate strip of paper or on the margin of the sheet on which the shooting is being carried out.
The scale of steps is built like this. Let's assume that the shooting is being done on a scale
1:10,000, i.e. 1 cm in the drawing corresponds to 100 m on the ground. The value of one pair of steps of the surveyor is 1.5 m. Therefore, 100 pairs of steps are equal to 150 m on the ground or 1.5 cm on the drawing. A 1.5 cm piece is laid on a straight line three, four or more times. The number 0 is written against the second division on the left, and the numbers 100, 200, 300, etc. are written against subsequent divisions. Against the leftmost (first) division sign: 100 pairs of steps. In this way we obtain a scale of steps, each major division of which
Corresponds to 100 pairs of steps. In order for distances to be plotted with great accuracy, the leftmost segment is divided into 10 small divisions of 1.5 mm, each of which will be equal to 10 pairs of steps.
Having such a scale, there is no need to convert pairs of steps into meters each time; it is enough to plot the number of pairs of steps taken on a scale to get the distance on the shooting scale, which is plotted on the drawing.
The shooting is carried out by walking around the site along roads, the banks of a river, the edge of a forest, along a communication line, etc. The directions along which the survey is carried out are called running lines, and the points at which the directions of new running lines are determined and drawn are called stations.
IMAGE OF LOCAL OBJECTS ON
TOPOGRAPHIC MAPS
Types of symbols of topographic maps. Local objects on topographic maps are depicted by symbols.
For ease of reading and memorization, many conventional signs have outlines that resemble the top or side view of the local objects they depict. For example, symbols for factories, oil rigs, free-standing trees, and bridges are similar in shape to appearance listed local items.
Conventional signs depicting the same terrain elements on topographic maps of different scales are identical in their outline and differ only in size.
The relief on topographic maps is depicted by contour lines, and some of its details (cliffs, ravines, gullies, etc..) - by corresponding symbols.
Conventional signs are usually divided into three main groups: large-scale, non-scale and explanatory.
Large-scale Conventional signs depict those local objects and relief details that can be expressed in size on a map scale (lakes, forests, residential areas, large rivers, ravines, etc.).
The contours (external boundaries) of such objects (objects) are shown on the map as solid lines or dotted lines in exact accordance with their actual outlines. Solid lines show the contours of lakes, wide rivers, ravines, residential areas, dotted lines show the contours of forests, meadows, swamps. The area inside the outline of such symbols on the map is usually covered with paint of the appropriate color or filled with additional
Signs (Tables 1, 4, and 5 of Appendix 3).
Scale symbols allow you to determine from the map the actual length, width and area of depicted or objects. For example, if the width of a river on a 1:50,000 scale map is 2 mm, then its actual width on the ground is 100 m.
Off-scale Conventional signs are used to depict local objects and relief details that, due to the small size of the area they occupy, cannot be expressed on a map scale. Such local objects are mines, radio masts, wells, tower-type structures, mounds, etc.
The exact position on the map of an object depicted by a non-scale conventional sign is determined by the geometric center of the figure, the middle of the base of the sign, the vertex of the right angle at the base of the sign, and the geometric center of the lower figure.
An intermediate position between scale and non-scale symbols is occupied by symbols of roads, streams, gullies, water pipelines, power lines and other linear local objects, for which only the length is expressed on a scale. Such conventional signs are usually called linear. Their exact position on the map is determined by the longitudinal axis of the object.
Explanatory Conventional signs are used in combination with scale and non-scale; they serve to further characterize local objects and their varieties. For example, an image of a coniferous or deciduous tree in combination with a conventional sign of a forest shows the dominant tree species in it (see figure), an arrow on a river indicates the direction of its flow, transverse strokes on a symbol railway show the number of paths.
The maps contain signatures of the proper names of settlements, rivers, lakes, mountains, forests and other objects, as well as explanatory signatures in the form of alphabetic and numerical designations. They allow us to obtain additional information about the quantitative and qualitative characteristics of local objects and relief. Lettered explanatory signatures are most often given in abbreviated form according to the established list of conventional abbreviations (Appendix 5).
