Discussion of DEM Standards,Quality Theory and Conceptions

We mainly discuss about some of the quality requirements in national standards.Some conflicts between these requirements and real data in practices are indicated.Based on the data quality theory of GIS,the error theory of DEM,ordered isomorphism of elevation and the generalization theory of DEM are analyzed in terms of resolution ratio,data logical consistency and integrality.DEM should not be the elevation of a specific sampling point but the typical elevation within the grain range(dx×dx),and DEM generalization plays a key role in DEM production.