光栅图形矢量化方法分析与评价,一篇不错的书籍-Raster graphics vector analysis and evaluation methods, a good book

DEM SRTM3的.hgt文件是1201*1201， signed 16 bits interger的 binary raster文件， Byte Order是Big Endian (Motorala / Network (IEEE))， 由于Signed 16 bits interger取值范围是-32767 to 32767， 其中数据空洞就赋值为-32768. -DEM the .hgt file is produced by America NASA

The Graphics Interchange Format (tm) was created by Compuserve Inc. as a standard for the storage and transmission of raster-based graphics information, i.e. images. A GIF file may contain several images, which are to be displayed overlapping a