Digital Art of Bas-Relief Sculpting

In this thesis, we present a semi-automatic method for the generation of bas-reliefs from a given shape. A Bas-reliefs is an artistic sculptural representation of a three dimensional scene which possesses a negligible depth. The main idea behind our method is to work with a range image, whose depth interval size is compressed in a feature preserving way. Our approach operates in the gradient domain, whereas we also present an extension which works on the Laplacian. The algorithm relies on the achievements of High-Dynamic-Range-Compression and adapts necessary elements to our purpose. We manipulate the partial derivatives of the range image rather than the image data itself. These derivatives are compressed by applying an attenuation function which leads to a relative convergence of the entries. By a feature enhancing technique we boost small details in order to keep them perceivable in the result. In the end, the compressed and enhanced partial derivatives are recombined to the final bas-relief. The results exhibit a very small depth range but still contain perceptually important details. A user can specify the desired compression ratio and steer the relevance of small features in the outcome. The approach is intuitive, fast and works very well for high compression ratios as experiments have shown. Possible applications are of artistic nature like sculpting, embossment, engraving or carving