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Proceedings Paper

Adaptive algorithm of shaded-relief images from DEMs based on wavelet transform
Author(s): Xiuguang Zhou; Egon Dorrer
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Paper Abstract

This paper presents an adaptive shading algorithm based on the wavelet transform. The mathematical relations between gradient spaces (p,q) and wavelet transform subbands are investigated. A set of formulas are provided to calculate the surface gradients from the wavelets. The DEM wavelet transform pyramid provides coarse to fine terrain structures from which the aligned regional main direction (RMD) and the local detail direction (LDD) of the terrain are automatically obtained. Based on the aligned direction of the terrain, the so-called regional main light sources (RMLs) and the local additional light sources (LALs) are automatically determined. The RML gives the regional main illumination corresponding to the RMD to provide a global shading situation, while the LAL gives the local additional illumination corresponding to the LDD to provide a detail shaded relief. The final shaded image is then obtained by a linear combination of the two shaded images with respect to the RMLs and LALs. Experimental results of the shaded images from Mars DEMs show that the proposed algorithm provides optimally shaded relief images.

Paper Details

Date Published: 1 December 1995
PDF: 13 pages
Proc. SPIE 2646, Digital Photogrammetry and Remote Sensing '95, (1 December 1995); doi: 10.1117/12.227869
Show Author Affiliations
Xiuguang Zhou, Univ. der Bundeswehr Muenchen (Germany)
Egon Dorrer, Univ. der Bundeswehr Muenchen (Germany)


Published in SPIE Proceedings Vol. 2646:
Digital Photogrammetry and Remote Sensing '95
Eugeny A. Fedosov, Editor(s)

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