DLG
Digital Line (DLG, Digital Line Graphic): it is consistent with the existing line draw vector data set of elements around the map, and save the spatial relationship between the individual elements and associated attribute information.
Mapping living word, the most common products that DLG, field surveying and mapping in general is the final outcome of DLG. The product is a more comprehensive description of surface phenomena, the visual effect is consistent with the same scale but the color is more abundant. We analyze, and randomly select and display data, and additional information is superimposed, spatial analysis can be performed, the product meet decision space. Wherein the partially formed core elements as digital orthophoto topographic map terrain features draw the line. DLG DLG.jpg.
Digital line (the DLG) is a more convenient amplifying, roaming, a query, inspection, measurement, overlay maps. Its small amount of data, to facilitate delamination, can quickly generate a thematic map, it is also known as vector thematic information DTI (Digital Thematic Information). This data can meet a variety of GIS spatial analysis requirements, regarded as data with intelligence. Data may be randomly selected and displayed, superimposed with several other products, ease of analysis, decision-making. Digital line (the DLG) technique wherein: the geographic map contents, framing, projection accuracy, the coordinate system is consistent with the same scale maps. Vector format graphic output, arbitrary scaling are not deformed.
Production technology mainly uses raw data: field data collection, aerial, high-resolution satellite images, topographical maps. Production Method:
1) digital photogrammetry, three-dimensional tracking perspective mapping. Currently, domestic digital photogrammetry software system and JX-4C VintuoZo DPW system only has a corresponding vector systems, and their high accuracy indicators. Wherein VintuoZo system and NT Workstation version of the two, and JX-4C DPW NT version only one kind of system.
2) or a computer-aided analytical Digital Mapping. This mapping method is a perspective view of the aerial and satellite images in high resolution analytical plotter or simulator, DLG data obtained. Need to use this method such as GIS or CAD graphics processing software, the data obtained for editing, the final results of the data generated.
3) of a conventional scanning topographic map, the interactive elements thereof vectorization. The most commonly used at home and abroad vector software or CAD software and GIS using the vectorization of scanned image after transferred to the appropriate vector system.
4) In the newly created digital orthophoto on imagery, digitized manual tracking frame element. Tracking on the screen: and can use CAD or GIS software VirtuoZo Orthophotomap certain proportion into a working area, and the corresponding elements in FIG acquired.
5) field survey map. (Basic process see Section Digital Mapping) DLG application of land-use planning and control; select the address of shopping malls, factories, transportation centers; urban construction and management; agro-climatic zoning; environmental engineering, air pollution monitoring; road traffic construction and management. Natural disasters, war, disaster, disaster monitoring other estimates of natural resources, cultural resources, the landscape changes people's livelihood industries (health care, public utilities, services, etc.).
THE
Digital Elevation Model (Digital Elevation Model, abbreviated DEM) is within a range of regular grid points plane coordinates (X, Y) and height (Z) of the data set, which describes the spatial distribution of the main topography regions, and the like by high dimensional model lines or similar data acquisition (including sampling and measurement), and interpolation data is formed. DEM is a virtual representation of the topography, can be derived contour information, etc. FIG slope, or may be superimposed with other DOM thematic data, for analyzing the application associated with the terrain, while the underlying data itself or the production of the DOM.
DEM is an ordered set is represented by an ordered set of numerical values with DEM form of an array of solid ground elevation terrain model is a digital terrain model (Digital Terrain Model, referred DTM) a branch. Generally considered, the DTM is a description of various factors, including topography, including elevation, such as slope, slope, gradient factors, including the rate of change of the spatial distribution of a combined linear and nonlinear, wherein DEM is the zero order model of a simple single digital physiognomy other characteristics such as topography, slope, aspect and slope and rate of change can be derived on the basis of the DEM. DTM other two branches are a variety of digital model represents a matrix of non-geomorphological characteristics, including natural geographical and socio-economic factors and human factors associated with the ground, such as soil type, land use type, depth of rock, land, commercial advantages zone and so on. In fact DTM is a raster data model. It represents the difference between the form of the raster image are: the image is a point representative of the pixel of the attribute, while in DTM, the grid points between the points only attribute indicates the attribute dots by the interpolation calculation obtained.
DEM method for establishing a variety of sources and from a data acquisition mode stresses are: (1) directly measured from the ground, for example with GPS, total station, field measurements and the like; (2) according to aviation or aerospace images, acquired by way photogrammetry stereoscopic observation and coordinatograph aerial triangulation method, or analytical methods, digital photogrammetry and the like; (3) collected from the existing terrain map, such as a read grid point method, digitizer hand tracking and acquisition scanner semiautomatic DEM is then generated by interpolation or the like. Many interpolation method on DEM, mainly watched the interpolation blocks, the interpolation section and the inner surface of the single-point shift interpolation three. The most commonly used method is to create a triangular irregular network by contour lines and elevation points (Triangular Irregular Network, referred to as TIN). Then TIN based on the linear and bilinear interpolation by building DEM.
Because it is ground elevation information described in DEM, which has been widely used in surveying and mapping, hydrology, meteorology, topography, geology, soil, construction, telecommunications, meteorology, military, economy and national defense as well as the humanities and natural sciences. As in the construction, it can be used as calculating earthwork, visibility analysis and the like; in flood mitigation, on DEM is hydrological analysis as catchment analysis, water network analysis, rainfall analysis, flood calculation, submerged analyzing the like; in wireless communications, the base station can be used for analysis of the cellular phone and the like.
DRG
In geographical terms, DRG is the abbreviation of Digital Raster Graphic, Chinese called Digital Raster: is based on the existing paper, film and other topographic map After scanning and geometric correction and color correction, are formed on the content, geometry and color accuracy with FIG topographic consistent set of raster data.
Map scanned, geometric correction, image processing and data compression processing, color map should be color corrected so that the color of each image consistent. Digital Raster (DRG) is consistent with the same scale topographic map in the content, geometry and color accuracy. Product The product is an analog to digital product transition product, it can be used as background reference image and other information related to the spatial reference and analysis. Data acquisition can be used to map the digital line, and updates the evaluation, but also with digital orthophotos, digital elevation model data such integration derive new information, creating a new map. Digital raster DRG.jpg
Digital Raster (the DRG) technique wherein: the geographic map content, visual appearance scale topographic map with the same pattern as the plane coordinate system 1980 Xi'an geodetic reference coordinate system; map projection Gauss - Krüger; elevation system uses 1985 national height datum. The image input is greater than a resolution of 400dpi; output is greater than 250dpi.
DRG can be used as a background or reference data revision and other geographic information fitting, for use in Digital Line (the DLG) data collection, evaluation and updating, but also with digital Orthophotomap (the DOM), dem (DEM) using other data integration. Derive new visual information, thereby extracting, updating map data, drawing paper maps.
JUDGMENT
Digital orthophoto map (DOM, DigitalOrthophotoMap): Is the aviation (or space) to digitally photograph and differential correction mosaic, map sheet according to a certain range of cutting-generated digital orthophoto collection. It is also has an image map geometry and the accuracy of image features.
DOM has a high accuracy, information-rich, intuitive and realistic, to obtain the advantages of quick, can be used as a map analysis background control information can also be extracted from historical information or the latest information on the natural resources and socio-economic development for the prevention of disasters and public facilities construction planning applications provide a reliable basis; can also extract and derive new information, to map revision and update. Evaluate the accuracy of other data, the reality and integrity are very good. Hefei digital orthophoto FIG DOM.jpg.
Technical features of the drawing are: digital orthophoto, framing the map, the projection accuracy, the coordinate system is consistent with the same scale maps, the image input is greater than a resolution of 400dpi; output is greater than 250dpi. Since the DOM is digital on the computer locally developed enlarged, good interpretation performance and measurement performance and management performance, such as issuing a rural land identified were sector boundaries using survey ratio and digitizes its coordinate points, land and many more. DOM as an independent background layer name and note names, FIG grid profile km, km grid composite layer and other elements, the production of thematic maps.
The main technical production methods: using high-resolution aerial photograph or a satellite remote sensing image data. By using: 1) VintuoZo digital photography system workstation. VintuoZo of DEM system may utilize detection and editing to improve the accuracy of the DOM. Also, inter FIG web between gradation photograph by Edge, to ensure consistency in image tone. 2) jx-4DPW system. jx-4DPW is a set of digital photogrammetry system WINDOWSNT. Edited because the DEM using a single edit point, and the system also has a function to zero DOM dimensional inspection, so that high precision DOM. DEM-based single-chip digital differential correction VintuoZo system with single-chip digital differential correction module.
Dynamic monitoring of land cover and land use of land resources;; Flood monitoring digital orthophoto map, the river changes, drought monitoring; agricultural yield estimation (Precision Agriculture) desertification monitoring and forest monitoring (forest pests); shoreline protection; ecological changes monitor.
DOM advantages main features: ease of use and strong, the use of DOM, XML documents will all information is stored in memory and simple traversal, supports XPath, enhancing ease of use. DOM shortcomings mainly in: inefficient, slow parsing, memory usage is too high, almost impossible to use it for large files. In addition inefficiency is also reflected in a large number of time-consuming, because the use of DOM parsing, each element will document, attribute, processing-instrUCtion and comment creates an object, create a large number of such objects in the DOM mechanism by the use of and destruction will undoubtedly affect its efficiency.