The volume-rendering client can act as a 3D roving microscope, allowing users to visualize data that is too large to fit on a single machine. The graphical user interface allows for interactive visual selection of transfer function and isosurface. The user interface also allows the user to move and resize the sub-volume window. The data within the sub-window is then transmitted by the server to the client computer, and displayed interactively using fast texture based volume rendering that can be combined with rendered geometry. The rover connects to a data server that contains large datasets. The server can extract and resample sub-volumes of different sizes, which are then transmitted to the client for visualization.