Abstract：Through a case of SRTM over nine vacancies of different size classes and three terrain types including hill, plateau and mountain the voidfilling accuracy of high accuracy surface modelling (HASM) with those of the classical interpolation methods including TIN, SPLINE and IDW with and without auxiliary data sources of SRTM30 are compared. The results indicates that no matter whether SRTM30 is used, HASM is more accurate than TIN, SPLINE and IDW. Compared with the classical interpolation methods, the filling superiority of HASM in complex area is higher than that in flat areas. Both the terrain type and area size of the voids have the effect on the voidfilling accuracy of HASM. HASM has a higher filling accuracy for smallsized voids in relatively flat areas than for bigsized voids in mountain regions. The auxiliary data of SRTM30 should not be used for smallsized voids in relatively flat areas, but it should be used to fill bigsized voids in mountain regions.
