Aerial Image Relighting: Simulating Time of Day Variations

We present a technique for simulating variations in appearance of aerial images at different sun angles. The input to the algorithm is a single aerial image with information on the orientation of surfaces in the image. The location, date, and time at which the photograph was taken are also needed by the algorithm. The appearance of the aerial image at a new sun angle is synthesized by compensating for the direct sunlight component in the original image, and then relighting the image with sunlight from the new sun position. Techniques to remove cast shadows are also described. We demonstrate our results with images, and animations of changing lighting in aerial photographs as the sun follows a trajectory across the sky.

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