DEM采样间隔对地形描述精度的影响研究

Study on the Influence of Sampling Interval on DEM Representation Accuracy

数字高程模型(DEM)的精度包括采样点数据精度和地形描述精度两方面,前人对DEM精度的研究多集中在DEM采样点精度,而忽视了地形描述精度。该文提出基于窗口曲面拟合计算拟合曲面系列参数与"实际地形"曲面参数的标准差来衡量地形描述精度的方法,研究发现DEM地形描述精度随采样间隔的增大呈降低趋势;并利用坡度频率曲线和坡度累计频率曲线研究对DEM精度敏感的坡度因子与DEM采样间隔的关系,认为随DEM采样间隔增大,坡度衰减(变缓)的速率加快。

The accuracy of DEM includes two aspects, sampling data accuracy and the terrain representation accuracy. Several re searches were focused on the sampling data accuracy. On the other hand, the terrain representation accuracy is often ignored. In this paper,a method is suggested to investigate the terrain representation accuracy. Firstly, the curves of DEM are simulated by window, and then the stand deviation of coefficients between a series of simulated curves and the so called ＂real terrain＂ is calculated. This method is used to discover the rules between the terrain representation accuracy and the sampling interval of DEM. Tests proved that this new method is useful for researches on scaling and accuracy problems of DEM. And also the relationship between the slope and the DEM sampling interval is studied by slope frequency curve and cumulative slope frequency curve. It is concluded that, firstly, as the sampling interval increases, the terrain representation accuracy decreases, but the reducing speed is slowed, secondly,as the grid size increases, the DEM still retains the basic framework information of the terrain, finally, when the grid size increases, the slope attenuation speed will increase.