Digital Correction of Solar Illumination and Viewing Angle Artifacts in Remotely Sensed Images

We seek to understand and correct shading artifacts caused by varying solar illumination conditions and different viewing angles in remotely sensed images. A synthetic image simulating the shading effects for the sun angle and viewing angle as a real image, is generated using a terrain reflectance model and digital elevation data. A good correlation is obtained between the real and synthetic images. The artifact correction is then made, and a resulting image shows useful information that is not apparent in the original image. We also present a three-dimensional perspective representation of a terrain with a corresponding aerial photograph mapped on it, which incidentally may help image interpretation.