Different existing methods for the rendering of different classes of data, i.e. surface and volume data, in one image are described and discussed. Two fundamentaly different strategies for combining the rendering of volume data with the rendering of surface or other geometric primitives have been developed. The first strategy is to convert either volume data into polygonal data or to convert polygonal data into volume data. Applying one of these conversions results in one class of data, which can be rendered with one appropriate rendering method. The second strategy is to use different rendering methods for the different classes of data and to combine the - perhaps intermediate - results in a final display. The rendering modules are either independent from each other or more or less tightly coupled. This includes merging the results of different rendering processes in the z-buffer of a workstation.