Abstract: This paper briefly expounds the related knowledge of topographic map, introduces in detail the important methods, principles and matters needing attention in the process of editing and drawing topographic map, and introduces the related topographic map editing software, and also mentions the important application of topographic map in various fields.

Keywords: topographic map topographic map editing

Chinese map classification number: TB23 document identification code: A article number: 1672-3791(2112)15(c)-1124-11

As a kind of expression of the spatial distribution, combination, connection, quantity and quality characteristics of various phenomena on the earth's surface and their time, Topographic map production is a complicated process. No matter which mapping method is adopted, topographic map editing process is indispensable. The quality of this process has a great influence on the drawing quality and future use. In a word, topographic map editing is the core work throughout the whole topographic map production process. How to edit a good map, so that map works can better serve social production and life. As a first-line surveying and mapping worker, based on my own work experience, I will discuss and analyze several important issues in topographic map editing as follows.

1 Understand the basic knowledge of topographic map

1.1 Concept of topographic map

To edit topographic map, you should first have a certain knowledge of topographic map, and preferably have professional knowledge, which is very important for editing the map well.

topographic map is a kind of ordinary map, and it is an orthographic projection map that shows the plane position and elevation of landforms and features according to a certain scale. Its basic characteristics are as follows.

(1) Geodetic survey results are used as the control basis of plane and elevation, and printed with longitude and latitude grids and rectangular coordinate networks, which can accurately represent the geographical position, topography and geomorphological features of topographic elements.

(2) Field surveying and mapping with aerial photogrammetry or field survey as the main means is detailed and accurate.

(3) The landform is generally represented by contour lines, which can reflect the actual height and undulating state of the ground, and has a certain three-dimensional sense, which can meet the needs of analyzing and studying the terrain on the map.

(4) Ground features generally represent natural and human elements, which are divided into independent ground features, residential areas, transportation networks (mainly land road networks), water systems, landforms, soil and vegetation, and boundary lines.

(5) There is a specified scale series.

(6) There are unified schematic symbols, which are convenient for identification and use.

in addition, in order to keep the topographic map current, it is stipulated that it should be updated regularly.

1.2 Matters needing attention in graphic editing

(1) Make preparations.

Before editing, you should first read the Technical Design Book carefully to get a detailed understanding of the background and details of the project. Including the purpose of the project, data format, software selection, precision control in editing, and the time limit for project completion. Every project may have its own special requirements. At this time, we should pay special attention to these, and we must never work only by experience, so as to cause unnecessary rework.

(2) deploy the software and configure the symbol library.

when editing topographic maps, the software and data platform used are often different according to the requirements of each project, the use of maps and the requirements of data formats. In the current environment, the topographic map produced by a project is no longer only for plotting, but also for building data base, maintaining and reusing data. Therefore, the data platform suitable for building database should be selected as far as possible in the selection of software. This is also the direction of efforts of various production units in recent years.

to measure the standard of a mapping software, we should first look at whether the software is suitable for the actual situation of our unit; Secondly, it depends on its operability, whether the interface is friendly, easy to learn and so on; Finally, it depends on whether the functions it provides are suitable for this unit.

At present, the software used by various surveying and mapping units can be described as varied and numerous. But there are basically two types, one is the system (unit) developed by itself, and the other is developed by a specialized surveying and mapping software developer, which is provided to the majority of users for commercial purposes, and is also used more by various surveying and mapping units. Generally speaking, the selection of software includes the following aspects: according to the data source, according to the use of topographic map (database building, mapping requirements, or both), according to the data platform or data format required by Party A, and so on.

our company has been trying and constantly improving its software configuration and selection. Now we mainly use MapGis, Geway, MicroStation, AutoCAD, Antu series, ArcGis, CASS series and so on.

In addition to using the software, tools and batch programs needed in this project, you can also use some software tools of similar projects in the past to hand over the work to the program as much as possible to reduce the workload and improve the editing efficiency.

2 Talking about the data editing requirements of topographic map in combination with the project "Digital Mapping of 1∶511 True Color Aerial Survey in Anyang City"

At the beginning of technical design, it is necessary to make data editing regulations according to the characteristics of digital topographic map of this scale, and complete the preparation of various resource files, including establishing template files, making public blocks, perfecting symbol library and line library, selecting unified font library, and formulating data hierarchy and code. These tasks should be done in detail, such as the determination of some very insightful object codes, and it is best to specify the layer code and bus data production method for each object.

2.1 data editing

DLG editing is the most critical link that affects data production. The editing of digital topographic map has already broken the traditional concept of cartography, and should give consideration to both cartographic data and bus data, which meets the requirements of CAD data conversion, and should be consistent with GIS industry standards in terms of mathematical benchmark (coordinate system), attribute accuracy, topological relationship and logic, as well as metadata production, file naming and data format.

(1) data to meet the needs of cartography and database building. The collection of all topographic map elements conforms to the basic requirements of spatial geographic data, which can be summarized as follows: lines should be connected, surfaces should be closed and points should be accurate.

(2) If polygon objects can be closed, they should be closed strictly; Polygons with male * * * edges are strictly captured (snapped) at intersections, and gaps and multiple overlaps are not allowed; The male edge is only collected once, and other layers are generated by copying. Polygons are not allowed to be represented by blocks.

(3) Line objects should be connected (that is, the acquisition should not be interrupted artificially. For example, it is not allowed to manually cut off the terrain elements just for the effect of plotting, and the software will complete the capping on the premise of keeping the terrain requirements intact); Different features must be captured reasonably according to the specifications, and unreasonable suspension is not allowed; If the program is used to generate special symbols, the skeleton lines and skeleton information must be kept intact and coded correctly.

(4) The dot symbol is not allowed to explode. In addition to dot symbols, graphic elements should avoid using block objects as much as possible.

(5) The symbol library and line library of topographic maps used in each process must be consistent. The size of symbol library and line library of various topographic maps must meet the reference standard, the positioning point of point symbol library should be consistent with the acquisition point of field surveying and mapping, and the line library must be made according to the right-handed rule.

(6) In order to ensure line connectivity, wipeout technology is used to cover symbols, bridges, etc., but the display order of elements should be adjusted; Especially bridges, which are represented by lines, should be considered separately. The text is masked to 1.15 wide.

(7) handle the suspension with the command of clearing the graphic surface; The parameter is set to 1.13; Pay attention to the requirement to add the outline of the internal diagram for processing;

(8) Look at the symbol masking and the text masking (1.1mm).

(9) data processing (map/graphic surface cleaning with Cass): repeated data processing (1.11m), hanging processing (1.11m), micro-short line processing (1.11m), etc.

(11) Drawing cleaning: cleaning of waste layers and other useless data, and layer color inspection.

2.2 data joining, outline trimming and data checking

The joining method adopted by our unit is generally to join the data editor of each picture with the top and left sides of his own picture sheet. This not only ensures that each edge is connected, but also facilitates unified management and avoids missing connections.

the outline decoration is generally in a fixed format, and it only needs to be filled in according to the situation of this project, in which the number of drawings and the combined table format need to be filled in carefully.

the most important thing after data editing is data checking. Data inspection is the most important quality control before data submission. We generally adopt the method of combining the first check, the second check and the spot check. Strict data check provides a strong guarantee for providing high-quality graphic editing results.

this paper explains the knowledge of topographic map and the important principles and methods in the process of map editing in detail. By solving the above important problems in topographic map editing, the editing of topographic map will become clear and clear, and the problems in general topographic map editing will be solved.

References

[1] Cartography [M]. Wuhan University Press.

[2] Yang Zhonghua, Chen Lin, Yu Mingquan, et al. Modern Applied Surveying [M]. Xi 'an Map Publishing House.