黄土丘陵沟壑区不同数据结构DEM转换精度研究

栅格DEM与TIN是DEM表面建模主要的2种方法。应用DEM进行地形分析时,栅格DEM与TIN的相互转换非常必要,但在转换中所产生的误差直接或间接地影响到分析结果的准确性。以陕北黄土丘陵沟壑区的绥德县韭园沟流域为实验区,采用高精度的1:1万DEM为基准数据,探讨不同转换参数对转换精度的影响。实验结果表明,所建立的栅格DEM表面高程误差随着TIN的转换阈值的增大而增大、所提取的地面坡度、沟壑密度的精度随之降低。TIN的转换阈值以5 m为较为理想的指标。

Conversion Accuracy Between DEMs of Different Data Structure in Loess Hill and Gully Area

The conversion between Grid DEMs and TINs is of critical significance in digital terrain analysis which is a key work in the watershed planning of the loess plateau region. Taking Jiuyuan watershed in Suide county of northern Shaanxi province as a test area and 1 :10 000 Grid DEM as a criterion, applying overlay comparative laws and mathematical statistics as basic research methodology, a research on the accuracy of conversion between Grid DEMs and TINs is made. The experiment shows that the conversion accuracy between Grid DEMs and TINs affected by conversion tolerance of TINs directly. The accuracy of Grid DEMs on describing terrain variables (i.e. elevation, slope gradient, channel network etc) decreases with conversion tolerance of TINs increasing, compared to Grid DEM of 1: 10 000. Five meters should be a rational conversion tolerance in the loess hill and gully area.