在不同空間解析度的DEM提取坡度的研究－以烏山頭水庫地區爲例

The Study on the Slope Information Derived from OEM with Different Spatial Resolutions-A Case Study of Wu-Shan-To Reservoir

簡耀鴻(Yao-Hung Chien) ； 張東炯(Tung-Chiung Chang) ； 王兆印(Zhou-Yin Wang)

《農業工程學報》 54卷2期 (2008/06) Pp. 1-8

https://doi.org/10.29974/JTAE.200806.0001

摘要

本研究以烏山頭水庫地區爲例，提供該區域一個有關提取起坡度而績比誤差回歸公式，做爲在不同空問解祈度提取坡度訊息情有合理化約根據。隨著高程數據獲取技術和儀器的進步，無論楚遙測影像的解析度提高或是光達(LIDAR)的應用，皆大大提高數值高程模型(DEM)的精度，由於DEM是對地形的一種模擬、近似趨近之數學模式，應用上，DEM是對已獲得的離散高程數據進行內插生成的，因此，不可避免地存有一定的誤差。這些誤差對不同的應用，例如提取地形參數〔坡度、坡向、集水面積、水系密度等〕有不同影響，工程界使用者常以DEM提取坡度數值，但如果未考慮不同空間解析度復坡度訊息提取時約不確定性，則對提取的坡度訊息無法提出一個定量的誤差大小。對於考慮不同空間解析度在坡度訊息提取時約不確定性，本文研究結果顯示，較陡坡度隨網格尺寸的增大而被簡約化，此簡約化造成坡度的取值範圍，隨空間解析度減小而縮小；分級坡度面積比誤差的對數值，皆隨空間解析度減小而趨近於一個收斂值，且該對數值和空間解析度呈現冪次函數關係。

關鍵字

空間解析度 ； DEM ； 坡度 ； 不確定性 ； 地理資訊系統

並列摘要

The main purpose of this research is to reach an error regression formula of the slope gradient to area ratio by case study of Wu-Shan-To reservoir area in Taiwan, in order to establish a basis for the collection of reasonable data extracted from DEM with different spatial resolutions. That the improvement of the technology and instrument for acquiring elevation data, greatly raise the accuracy, of Digital Elevation Model (DEM) by increasing the resolution of remote image, or applying LIDAR. Because DEM is the model of mathematical simulation, an approximate method, and in application, DEM is generated by interpolating the acquired discrete elevation data. Hence, the inaccuracy and error are inevitable. The effect of those errors, such as on the extracted topography parameters (e.g. slope gradient, aspect, water catchments are, river density, etc) varies depending on different applications of DEM. hi engineering field, DEM is usually used for the extraction of slope gradient data. Without considering the uncertainty of different spatial resolutions, the amount of error can not be quantified. For considering the above mentioned uncertainty, the result shows that sleeper slope gradient is to be simplified as the grid size increases, which makes the range of picking up the slope gradient will be decreased as the spatial resolution reduced. Logarithmic value of the error of the divided slope to area ration is decreased and converged to a value as the spatial resolution decreases. And there exists a power function relationship between the logarithmic error value and spatial resolution.

並列關鍵字

Spatial resolution ； OEM ； Slope ； Uncertainty ； GIS