基于全数字摄影测量数据建立DEM时分辨率的确定

Determining DEMs′Resolution with Digital Photogrammetric Data

分辨率是栅格DEM的基本参数之一,其大小直接影响到DEM的数据质量和地形分析的精度。采用多大的分辨率是建立和应用DEM时需解决的基本问题。利用全数字航空摄影测量方法,获取了位于陕北丘陵沟壑区的实验样区的高精度地形特征点、线数据,在此基础上,生成了9种不同数据密度的点数据集。然后利用ANUDEM和TIN方法,建立具有不同格网尺寸的2种DEM数据系列,并提取坡度均方差,平均坡度和高程中误差。根据坡度均方差、平均坡度和高程中误差随格网尺寸变化的规律,确定了建立DEM时合适的分辨率大小。研究结果表明,在利用全数字摄影测量方法建立1∶10 000比例尺的DEM时,应采用的分辨率约为2.5m。

As one of basic parameters of gridded DEMs, resolution influences the quality of DEMs and the precision of terrain analysis. Choice of a suitable resolution is the basic problem to solve in generating and using DEMs. Based on the terrain features data with high precision of study area in northern Shaanxi Prov ince, which are extracted by the full digital photogrammetry, 9 source data with different data densities to create DEMs are obtained. Two types of DEMs, i. e. , ANUDEM and TINDEM with different grid sizes, are generated using the source data, and RMS slope, average slope and RMSE of elevation are extracted from the DEMs. According to the relationship between the grid size and RMS slope, average slope and RMSE of elevation, a suitable resolution is achieved. Results show that the suitable resolution for building DEM by the full digital photogrammetry is about 2.5 m in scale 1 ： 10000.