Characteristics and drawing methods of the most po

2022-07-26
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The characteristics and drawing methods of map plate making and printing technology (Part 2)

next, I will introduce in detail the process of drawing maps by GIS in combination with the MAPGIS software developed by Wuhan Zhongdi Information Engineering Company of China University of Geosciences

the basic process flow of mapping can be simply described as:; Scan → vectorization → dot line → generate standard frame → error correction → map mosaic → create area → generate engineering file → map output

The scanning input method provided by the intelligent Scanning Vectorization subsystem of

gis is to directly scan the original drawing through the scanner, store it in the graphic or image file (such as TIFF format) in the form of grid, and then convert it into vector Jinan assay steel hammer electronic universal experimental machine technical problem data through vectorization, store it in the line file (*.wl) or point file (*.wt), and then carry out and output. In addition to vectorization of binary scanning image, it can also automatically recognize and track vectorization of gray scanning image and color scanning image. In vectorization, it has the functions of returning points, adding points to guide, selecting and so on, which can effectively select the required graphic information, eliminate unused elements and miscellaneous points, reduce the workload of later graphic finishing, and can process the graphics hierarchically at the same time

The

grapher provides the function to analyze the spatial data and graphic attributes of point, line and face. Topology processing has changed the method of establishing topology relationship manually, which makes the tedious work of region input and sub region input quite easy, and greatly improves the efficiency of map input. Use the load file function to load the original digitized point and line files into the work area, and correct the errors. When building the area, first save the completed line file, and then delete the lines irrelevant to the area (such as rivers, roads, fault lines), or use the layer operation function to separate these lines from the lines of the area. Then the intersection of curves is processed, including line cutting and intersection matching. When creating an area, first turn the "line to arc segment", then "topology reconstruction" to create an area, then search the sub area to create the nested relationship of the area, and finally save the area file

in the process of graphics scanning or digital input, the input graphics have local or overall deformation due to operational errors, the accuracy of digital equipment and the deformation of drawings. The errors of graphic data and attribute data mainly include: incomplete data, including spatial points, lines and planes, loss of data, omission of regional center points, disconnection caused by vectorization of grid data, etc; Inaccuracy of spatial data location, including inaccuracy of spatial points, too long or too short line segments, broken line segments, non coincidence of adjacent polygon nodes, etc; The scale of spatial data is inaccurate, deformed, incomplete, incorrectly connected, etc. In order to eliminate the deformation of the input graphics and achieve the manufacturing accuracy of the graphics, after the graphics are input, the error correction system can be used to correct the position deviation of the whole graphics or a block or local primitive in the graphics caused by mechanical accuracy, manual error, drawing deformation, etc. The system automatically collects the values of actual control points and theoretical control points, establishes a corresponding relationship between actual values and theoretical values, and calculates the error coefficient of each actual control point, so that the point, line and surface data around each actual control point can be corrected according to the obtained error coefficient, and finally the purpose of correcting the whole point, line and surface file can be achieved. After correction, the map is more accurate

when all the work is completed, we will combine the point, line and area files into project files based on the project files described in the layout, and merge multiple files of the whole map, that is, draw a map and output it

gis has prepared various output functions of postscript format files, including PS files for Beida founder rip, PS files for other rip, and EPS files in accordance with adobe AI standard format. Transfer the postscript output file directly to the laser Imagesetter to output four-color films

the use of GIS for map plate making has unparalleled advantages, which are embodied in:

1. the graphic input operation is relatively simple and reliable, and can meet the needs of the project.

gis has a variety of input means such as digitizer input and scanning only input, and can automatically carry out line segment tracking, node adjustment, line segment node cutting and extension, automatic generation of polygon topology, and nonlinear correction of drawing deformation, And automatic error detection, which greatly simplifies the graphic input operation, ensures that our technology can significantly reduce greenhouse gas emissions, and proves the reliability of the input. It is especially suitable for large graphic input

2. the map produced and published has high accuracy.

gis has rich graphic tools and powerful graphic processing ability. Its functional design conforms to the mapping process of China's maps, can correctly handle the capping and avoidance of map elements and the gradual change of river lines, can easily carry out map text typesetting and annotation, can automatically generate standard picture frames, can convert various geographical coordinates, and can easily design defined linetypes, symbols, filling patterns and chromatograms. You can "WYSIWYG" output graphics to a variety of different graphics devices. It also has an interface with standard page description language postscript, which can output color separation and plate making films, and the graphics produced are of high precision

3. integrated management of graphic data and application data

in GIS, the graphic data of the map is stored in a strict point, line and surface topology structure and managed by the graphic database. At the same time, various professional application data are managed by the professional attribute database, and the two are connected through key words, so as to realize the integrated management of graphic data and application data. The image registration and mosaic system provides a powerful control point environment to complete the processing of image geometric control points, so as to complete the registration between images, the registration between images and graphics, image mosaic, image geometric correction, geometric transformation, gray transformation and so on in real time

4. seamless splicing of up to thousands of maps can be realized.

gis can automatically splice large-scale rectangular maps and small-scale sector maps. It can also automatically or semi automatically eliminate the edge connection error between maps, as well as cross map terrain retrieval and attribute data retrieval, and cross map clipping to meet the needs of different applications

5. the variety of maps is increased, the scope of services is broadened, and 3D stereograms, visual stereograms, ground cutting density maps, slope maps, slope aspect maps, etc. that are difficult to be achieved by conventional methods can be made

6, digital map can be easily applied to various fields of computer reading, analyzing, managing and inputting topographic information (such as information acquisition and output in GIS)

the digital map is easy to store, which ensures the non deformation of the storage, improves the accuracy of the map, and is convenient for remote transmission and processing

7. it accelerates the mapping speed, shortens the mapping cycle, and improves the process of mapping and plate making printing.

the development of science and technology, like dominoes, accumulates more and more energy and develops faster and faster. With the continuous progress of science and technology, new technologies have emerged with good appearance effects. The plate making and printing of maps will develop in the direction of making it easier, more practical, and more convenient to put the level on the outer circle of the oil cylinder and find the level according to the vertical and horizontal positions and horizontal directions of the base.

information source: Department of planning, China University of Geosciences (guqiong Julie)

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