Based On The Method Of Direct Positioning Of Spaceborne Sar Images

In recent years, the SAR technology developed quickly, and the image of SAR applied widely in geography. SAR have been one of the most important sensors in space remote sensing because the SAR can observe all-weather and all day, and the resolution of the image did not influence by the sensor' s height.At first, this article introduces the digital imaging principle of the SAR image, deduces the mathematic expression of the Range- Doppler model. On the base of analysis the R-D model function in image location, we ascertained the direct location based of the SAR assistant data and verified the algorithm.Contents in the article include :U The location theory and method which using the R-D model and earth model without the Ground Control Points (GCP)and Digital Elevation Models(DEM);2. The location theory and method which using the R-D model and earth model without the GCP but DEM ;3. The location theory and method which located the object using the stereo SAR image;4. The principle .progress and the method which resolved the satellite state vector;5. The test between two methods which located directly using the single image , one located without GCP or DEM , the other located without DEM. Results of the test implied that the location accuracy acquired from the method which located objects directly using the ERS image achieved the demand of the 1:250000 topographic map.