Analytical method for GIS basic data acquisition
Li Deren, Ge Renyan, Wang Shugen
Wuhan Technical University of Surveying and Mapping,
Wuhan, China
Abstract
The good base height ratio and high space resolution of SPOT imagery make it possible to be handled on analytical photogrammetric instruments. After a brief analysis of the geometry of SPOT imagery and a series investigation of software system of PLANICOMP analytical plotter, an analytical plotting software package of POST imagery at c-130 and a software for the production of orthophotoes from SPOT imagery on Orthoprojector OR-1 have been developed. Using the panchromatic SPOT stereo pair over the area of Marseille in the south of France, some experiments have been carried out.
A topographic map of 1:50,000 scale has been on c-130 analytical. According to the residuals in 32 check points the means square errors in X, Y an Z coordinates are dx +5.4m, dy +7.1m, dz +5.5m which can meet the accuracy demands of 1:50,000 map in mountain areas. A 1:50,000 orthophoto of SPOT imagery has been also produced by using OR-1. The mean square error of position in orthophoto is +0.29mm which fairly meets the requirement of 1:50,000 map. Because of two time duplication the object resolution of SPOT imagery was not so good. The whole investigation shows that mapping from space would be available and effective.
Introduction
One of the important basic data for Geographic Information System (GIS) from 1:50,000 & 1:100000 scale topographic maps. Therefore, the mapping of these scale maps from SPOT imagery, which gives us a very high geometric accuracy, is becoming a world widely concerned problem at present. Some European countries' research works show that mapping and map revision can be accelerated using the SPOT satellite images. The map revision cycle can be reduced to 2-3 years for 1:50,000 map and only 1 year for 1:10000 map. To the area where no maps have been made, the stereo observation ability and high resolution of SPOT imagery can supply with the about 10 meters demand of middle elevation accuracy, and with the plane accuracy of 10-20 meter which can meet demand of middle scale mapping productions. Besides these, SPOT images can also be used for producing orthophotoes and other thematic maps. The work cab be done by using modern analytical photogrammetric instruments, so long as the corresponding software are developed.
Method for calculation of exterior orientation elements
According to the geometry of SPOT imagery, the calculation of exterior elements had some different methods. For example, the bundle adjustment, the processing method of frame central projection, and the processing method of line central projection. All above methods have obtained some satisfied results, but if these processing methods are used for the calculation of orientation elements on analytical plotter PLANICOMP c-130 some problem will rise. For instance, the required amount of internal storage is too large, the calculation speed is slow and the obtained exterior orientation elements are not corresponding with the orientation parameters of analytical plotter etc. in this paper, a space resection method which is suitable for the calculation of exterior orientation elements from SPOT imagery on analytical plotter is submitted .
