Two methods for wavelet-based volume rendering

This paper describes two methods for wavelet domain rendering of volume data sets, which are based on entirely different paradigms for the approximation of the underlying volume rendering equation. The first approach comprises a ray-tracing algorithm for cardinal B-spline wavelet representations of both color and opacity values and generates high quality images. We especially propose elaborated integration and evaluation schemes, where the computation of shading is also performed in wavelet space. The second approach proposes a fast intensity integration method based on wavelet splats. This scheme takes advantage of the self-similarity of the basis functions and computes the required splats by Fourier projection slicing. At this point, it unifies the advantages coming along with Fourier domain and with wavelet domain rendering and it avoids some of the major artifacts the first one is prone to. Due to the computational efficiency, the splatting method allows the computation of coarse approximations at interactive rates and refines the picture progressively. (C) 1997 Elsevier Science Ltd.