The Influence of DEM Accuracy on Topographic Correction of Ikonos Satellite Images

Abstract

There is no research which specifically investigates the influence of the Digital Elevation Model (DEM) on topographic correction of satellite images. Such an investigation is necessary in view of the very high resolution (VHR) of recent sensors such as Ikonos and QuickBird and the low availability of accurate height information for the derivation of slope and aspect values. A comparative study of multispectral Ikonos images is presented using eight selected interpolation techniques with contour data. The DEM influence was evaluated by analyzing the variance and classification accuracy of topographically corrected images using the different DEMS. These were found to vary widely, with a 30 percent reduction in variance and a 20 percent improvement in overall classification accuracy between the worst and best performing interpolation techniques. Furthermore, smoothing techniques commonly used for the removal of noise in interpolated contour data or in existing DEMs were found to offer no significant improvement in intra-class variance or classification accuracy, when used with a grid resolution compatible with VHR images. However, a more rigorous planar slope function was found to be more effective, and when combined with the best interpolator, the natural neighbor, or Sibson, method, very high classification accuracy was achieved in the topographically corrected images.