Map production process

First, map knowledge overview
Map mapping belongs to the category of surveying and mapping industry. It is a natural discipline that studies the morphological characteristics of the surface of the earth's spheres and displays the spheres' surface in proportion to the three-dimensional coordinates. It can be used for military, aviation, aerospace, navigation, land transportation, and civil affairs. The government administrative departments such as forestry, geology, metallurgy, petroleum, water conservancy, agriculture, and public security provide information on administrative management, planning, construction, rescue, and disaster relief. With the continuous improvement of people's material and cultural life, the use of maps has become increasingly widespread. Today, with the reform and opening up, due to the transformation of the old city, the expansion of the city, and the extension of road traffic, the updating of the map has become increasingly urgent. In the late 20th century, the application of computer technology added strong wings to the map life. Map production has entered a new era.
The maps can be roughly divided into the basic scale maps of the country, such as: 1:5 hundred, 1:1 thousand, 1:2 thousand, 1:5 thousand, 1:10,000, 1:2.5 million, 1:5 Ten thousand, 1:100,000, 1:200, 1:25, 1:500,000, 1:1 million; administrative division maps, such as: town (township), county (city, district), province (region, real) Municipality), the country, the world administrative area map; special topics (collection, volume) of other professional disciplines, such as: planning map, population density distribution map, agricultural area map, geological map, etc.
Because of the strict mathematical precision required for maps, the production process of the map has relatively high requirements on the quality of the results. The accuracy requirement is usually accurate to ±0.1 mm. The map production process is briefly described below:
Second, map projection
In the surveying and mapping work, we must first find out the problem of map projection. The surface of the earth is a surface that cannot be unfolded. To represent the surface of the earth on a plane, the surface of the earth must be mathematically represented on the plane. This method is called map projection. Map projection is a method that specializes in the study of map projection theory, calculations, and the composition of cartographic networks, as well as the conversion between different projections. The basic methods of map projection are geometric perspective and mathematical analysis. Map projection is divided into isometric projection, equal product projection, and arbitrary projection according to the nature of deformation. According to normal position projection, conical projection, pseudo-azimuthal projection, pseudo-cylindrical projection, pseudo-conical projection, multi-cone projection. The current map in China uses an equiangular transverse (knife) cylindrical projection (Gaussian-Kruger projection). Internationally-used navigational charts are generally isometric cylindrical projections (Mercato projections). Due to different tasks and features, various maps have different requirements for map projection. When selecting a projection, map contents, map use and usage, map scale, map reader object, map projection speciality, and map must be distinguished. Different types of projections are selected for the form of publication, relationship with other maps, etc. Therefore, the proper selection of projection methods directly affects the mathematics basis of the map and the social benefits.
Third, map preparation
The map compilation is based on the map projection and studies the theory, methods and techniques of using cartographic data to compile maps, map synthesis and editing of map contents.
The methods for making maps are usually divided into field surveys and internal editing. The results of field surveying and mapping are various large-scale topographic maps, such as 1:500, 1:1000, 1:2000, 1:5000, and 1:10,000. Due to the large size and inconvenience of splicing, these basic fractal topographic maps cannot meet the usual needs and sometimes must be reduced in use. However, the graphical features such as line drawing, symbols, and notes on the drawing are smaller and smaller than the original drawing, and the topographic density of the drawing is increased, and the drawing area is smaller, which brings difficulties in reading and using, even To the extent that it cannot be used, it is necessary to draw down maps of various medium and small scales based on topographic maps and other mapping data. The mapping process of using the internal industry method to compile maps can be divided into four stages: editing preparation phase, original drawing compilation phase, printing preparation phase, and map printing and printing.
1. The preparation for editing is the preparation of the design phase of the map. The main contents include: collecting cartographic data, conducting analysis and research, assessing the quality of the quality, determining the method and degree of use of maps, studying the cartographic area, understanding the geographic characteristics, and being familiar with the cartographic data and in-depth study of regional conditions. Based on the characteristics of the area, the purpose and scale of the map, determine the contents of the map, the presentation method, the operating procedures, and the principles for the integration of the various elements, and finally write an outline (editing plan).
2, the original map compilation is the stage of making the original map. This is a creative work. Using the theory and techniques of cartographic synthesis, the cartographic data is comprehensively selected, and the original map of the newly edited map is obtained as a basis for publishing the painting. The first step is to choose the projection, make the mathematics foundation for calculating and displaying the map. In general, the data used in the compilation is reduced by using the compound illumination method, which is then printed into a blueprint and embedded in the plane of the map. Then the content of the map is compiled on the blueprint and becomes the original drawing. The content of the original image must be correct and consistent with the purpose of the new map. The depiction must be precise and precise. Therefore, all work processes for compiling maps should be conducted in accordance with the rules of compilation and editorial planning. Finally, we must also carry out border review and proofreading. In the course of the job you need to fill in the photo album.
3. Preparation for printing is the stage for making original prints and reference drawings. Drawing a printed artwork is a technical task aimed at improving the quality of the drawing and obtaining a printed artwork that is suitable for the reproduction requirements. Since the original drawing is made using a variety of data, after comprehensive selection and modification is completed, it is impossible to improve the quality of the drawing. In order to obtain a high-quality printing drawing, it is necessary to draw and process, that is, the work of painting. The original drawing will be edited and blueprinted, and all the content elements will be cleared on the blueprint to become the original print. Another method is to make the original drawing through high-precision photo-printing on a transparent material with a light-shielding film layer to make an original drawing instead of the original drawing. Cleared or carved symbols must conform to the rules of the corresponding scale.
Also make a reference map for use in color separation platemaking.
4, map printing India is a large number of stages of the map. Obtain a large number of prints by printing. The original artwork is taken as a copy of the film or plate, or the film is directly copied from the original and the plate is printed on the metal plate. The graphic text on the metal plate is transferred to the paper with an offset press to produce the image. A lot of maps. The map printing and printing stage is the last stage of map production. The quality of this stage directly affects the quality of the finished product map. So usually in the professional map printing and printing workshop equipped with a number of professional and technical personnel, to participate in the production process, from the printing plate, the printing environment, printing pressure, the pH of the fountain solution, the choice of printing ink, the printing ink additive deployment, printing network Purpose To monitor the quality of finished drawings in terms of reduction detection, paper deformation effects on finished products, and so on.
Now the application of computer technology, professional surveying and mapping software development, the formation of three-dimensional coordinates of the external mapping data acquisition, internal and external industry graphics data processing operations within the integration process. If you use the existing maps to edit the map, you can use scanning to form a raster image, then vectorize the graph data, and draw the original artwork through a high-precision plotter. After the original drawing is edited and examined step by step, it can be directly edited in the computer to make it meet the requirements of the drawing. The SO sheet is output by the laser discharge machine and printed directly on the machine. The application of computer graphics technology can shorten the cycle of drawing and reduce the economic cost, so as to achieve the purpose of improving the quality of finished products.