For the building shadow in downtown area, it adopts the Shadow Automated Extraction Method of IKONOS Images Based on Image Fusion to extract and the Lamber model to rectify;

对城区建筑物阴影，采用基于影像融合的IKONOS影像阴影自动提取方法对阴影进行提取，再采用郎伯模型进行校正；

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Not too difficult, place the barometer by the building, measure shadow, measure shadow of building, adjust by the known height of the barometer.

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