The preprocess technology includes color alteration, image match, Cross Area Correction, color alteration for altering the difference of color, and image match and Cross Area for altering the correction difference of geometry.
The digital photographs of measure, in application of calculator technique, handle digital image, the image match, the mode identification and other theories and methods,, and replace the person's eye stereoscopic observation with the calculator sense of vision, with its product and the middle digital record and the processed primitive data all numeral, comparing with the production method of digital product by normal regulations, has the strongpoint of high automation, fast speed, ∶result diversification etc.
As evidenced by both theoretical and experimental results,even the match calculation of single image according to DEM data obtained on a 1∶50000 relief map can yield a precision up to the requirement for scale 1∶50000 geological map spotting.
Stereo image matching is the key link in extracting elevation information from SPOT data. Based on the SPOT data analysis of the geometric and the image quality, a new method of multi-level image matching are proposed. Experiments in real image pairs show that, using the method, not only the good precision and the reliability are obtained but also the processing speed is high. The new method can be used to rapidly generate DEM for remote sensing data analysis.
A algorithm for digital stereo matching images based on feature points has been discripted. This m othod firstly extracts the feature points using Frstner operator, and then matchs same feature point in two image with a method named relaxative iterative method. This method has shown a good furture for automatic relative orientation and generation of Digital Terrain Models.