各种插值程序，是学习DEM的号东西，是我在学习DEM时候精心编写的。-A variety of interpolation procedure, a resolution of DEM to learn things, when I was well prepared to learn DEM.

The method retuns Interpolate elevation value based on the upper level DEM(Digital Elevation Model) data underlying. It can be used while rsizing the bit size of bil file, as per saying, using this method i was able to convert 32x32 bits bilfile to 6

通过线性内插SRTM DEM高程到ICESat星下点位置(Interpolate the SRTM to the ICESat location via linear interpolation)