In order to make direct volume rendering practicable convenient visualization options and data analysis tools have to be integrated. For example, direct rendering of semi-transparent volume objects with integrated display of lighted iso-surfaces is one important challenge especially in medical applications. Furthermore, explicit use of multi-dimensional image processing operations often helps to optimize the exploration of the available data sets. On the other hand, only if interactive frame rates can be guaranteed, such visualization tools will be accepted in medical planing and surgery simulation systems. In this paper we propose a volume visualization tool for large scale medical volume data which takes advantage of hardware assisted 3D texture interpolation and convolution operations. We demonstrate how to use the 3D texture mapping capability of high-end graphics workstations to display arbitrary iso-surfaces which can be directly illuminated to enhance the spatial relations betw...