雷射入射角與空載光達穿透率關係探討

On the Laser Incidence Angle and Airborne LiDAR Penetration Rate

黃清美(C.M. Huang) ； 史天元(T.Y. Shih)

《航測及遙測學刊》 13卷1期 (2008/03) Pp. 67-73

https://doi.org/10.6574/JPRS.2008.13(1).6

摘要

空載光達原始點雲資料包含地面點與地物點，以空載光達產製數值高程模型時，地面點之密度與分布影響其對地形描述之詳實度有絕對之關係。因此，在表現資料品質優劣時，地面點點雲密度爲重要指標之一。地面點密度高且分布均勻時，較能正確地展示地形面。地面點密度除受原始點雲密度之影響外，穿透率爲另一重要因子。穿透率受地表覆蓋物型態、雷射入射角與航高等因子影響。本研究以雷射入射角對穿透率的影響爲探討目標，使用實測航帶，依平行航向五等分，作爲五種不同雷射入射角之統計單元，分別求取各等分之穿透率。實驗結果顯示，當雷射入射角越小時，穿透率越高，反之亦然，航帶中間分帶穿透率約是面向航向最右五分之一（右二）及最左五分之一（左二）分帶的1.6倍，是由右方起第二個五分之一（右一）及第四個五分之一（左一）分帶的1.3倍。

關鍵字

點雲 ； 密度

並列摘要

The point cloud obtained from airborne LiDAR is composed of ground points and non-ground points. The density of ground points is an important index for characterizing the quality of DEM. When ground point density is high and distributed evenly, topography can be presented with high fidelity. There are a number of factors which may influence the ground point density. In addition to the density of the original point cloud, penetration rate is another essential factor. Penetration rate is influenced by land-cover types, incidence angle, flying height, etc. This study investigates the influence of incidence angle on penetration rate. Partitioning a flight line into five segments along the flight direction, the penetration rates are computed. It is shown that the penetration rate is higher with smaller incidence angle. The central segment of the flight line is 1.6 times of the right most and left most sections, and 1.3 times penetration rate of next right and next left sections.

並列關鍵字

point cloud ； density