中文摘要：

局部分析窗口大小是DEM坡度计算的关键因素之一。首先建立不同分析窗口下的坡度精度模型,讨论拟合曲面和DEM地形曲面匹配程度的分析方法,然后以分布在不同地貌类型和地形特征部位的样点为研究对象,分析不同窗口大小对坡度计算的影响规律;通过χ^2检验法,研究不同分析窗口下拟合曲面和DEM曲面的匹配程度,最后综合考虑两个方面的影响,探讨基于DEM坡度计算的适宜窗口。研究主要结论为：①坡度计算精度随着分析窗口的增大而提高;②随着分析窗口的增大,拟合曲面与DEM地形曲面之间匹配性逐步减弱;③坡度计算的精度应该在拟合曲面和DEM地形曲面相匹配的前提下,通过适当扩大局部窗口来获得,推荐5×5局部分析窗口为DEM坡度计算的适宜窗口;④DEM地形参数计算中,不应过分的追求计算精度而忽视形态的相似性,否则尽管地形参数的精度很高,但只具备数学意义而没有地形意义。

英文摘要：

The size of local moving window is one of the key factors when slope is derived from grid based DEM. In the paper, slope accuracy model based on the size of DEM local moving window is firstly presented and a methodology to evaluate quantitatively the loss of topographic detail is proposed through a Z2 -test of the corrected residuals in immediate neighborhood of the evaluation point. Then based on samples of different terrain positions at selected test area, this paper discusses the effect of the size of local window on slope accuracy and analyzes the match of the fitness surface and DEM terrain surface. Lastly, this paper provides a suitable size of window for deriving slope based on grid DEM. The results of the research show that. （1） the slope accuracy can be increased with increasing the size of evaluation window; （2） the comparability of the fitness and DEM terrain surface is lowered when the size of window is become larger; （3） under the condition of the fitness matching the DEM terrain surface, the slope accuracy can be improved through enlarging the window size and 5×5 local moving window is suggested for calculating DEM slope; （4） attention should be paid to the shape of the fitness surface that can be really described the DEM surface in terrain analysis based on DEM, otherwise the results of terrain parameters, such as slope, aspect and curvatures, are only provided with mathematical meanings and can not express the terrain features of DEM.