With the implement ofhe great development of Western area in China and the eautifyingthe mountains and rivers-lands project it is necessary to make clear theaccuracy of the slope derived from different spatial scale DEMs.

• 随着西部大开发和山川秀美工程的实施，许多部门急需搞清由国家地形数据库中不同空间尺度下的DEM提取的地面坡度精度到底有多高。