The Effects of Image Compression on Automated DTM Generation
نویسنده
چکیده
The effects of JPEG compression on automated DTM extraction via the approach of feature-based matching are investigated. JPEG lossy compression involves a truncation of higher spatial frequency data, a process which influences the accuracy of computation of grey-value gradients in the feature determination phases of image matching. Resulting accuracy effects on DTM heights obtained via the MATCH-T software system are investigated using a single stereomodel of 1:18,000 scale aerial photography at digital image resolutions of 15, 30, 45 and 60 μm. Heighting errors are computed for a range of compression ratios from 2:1 to about 40:1, illustrating that the impact of compression on DTM accuracy can be significant. It is concluded from this study that it is preferable to use the highest resolution available and to compress the image to the maximum extent allowed given the constraints of accuracy and image file size.
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