面向测图的遥感影像压缩几何质量评价

Geometric Quality Assessment of Remote Sensing Image Compression for Mapping

卫星测图应用中,遥感影像压缩几何质量评价对于制定合理的星上压缩指标具有重要参考意义。该文从影像匹配精度评价、自动生成DSM/DEM的精度评价和摄影测量点定位精度评价方面进行几何质量评价,并分析影像压缩比与不同地形类别的重建影像质量间的关系。试验结果表明,对于国产星上SPIHT压缩算法,在压缩比4∶1的条件下,由重建影像立体像对自动生成的DSM可以满足1∶5万数字高程模型高程中误差最低要求;在压缩比2∶1的条件下,重建影像立体像对摄影测量点定位精度满足所有地形的1∶5万测图规范要求。

In satellite mapping application area, geometric quality assessment for remote sensing image compression is of great importance for onboard compression index determination. The paper proposed an integral geometric quality assessment plan for remote sensing image compression, which included image matching accuracy assessment, effects of compression on automated DSM/DEM extraction, and photogrammetic point determination accuracy assessment. Image matching accuracy analysis showed how degradation in image quality associated with lossy compression can affect matching accuracy. In analyzing effects of compression on automated DSM/DEM extraction, a DSM was extracted from the original stereopalr and held as the reference against which the terrain heights obtained from compressed imagery were compared. Similar to DSM extraction accuracy analysis, photogrammnetric point determination accuracy analysis was to compare the accuracy of two sets of 3D coordinates of the feature points that are from original images and reconstructed images. The relationship between compression ratio and terrain types was examined. As to modified SPIHT algorithm adopted in Resources Satellite-3, the experiment results showed that compres sion ratio was considered to be no more than 4 ： 1 to satisfy 1 ： 50 000 DEM specification and no more than 2 ： 1 to sadsfy 1 ： 50 000 remote sensing mapping specification.