VTK is a powerful 3D data visualisation package written in C++, with wrappers for Python, Java and Tcl. The pipeline structure of VTK allows many different filters to be applied to a dataset in sequence, giving the user a large amount of freedom and control over the way their data can be displayed. Interactive widgets can also be created, providing further useful ways to examine datasets. In addition, the "level of detail" rendering feature and support for parallel computing make VTK suitable for efficiently processing and rendering large datasets while still allowing interactivity.
ParaView is a graphical tool, built on the VTK package, which provides most of the features of VTK. The ParaView interface gives easy access to a wide selection of filters, along wth control over every stage of the pipeline and multiple interactive rendering windows. ParaView also allows customisation through programmable filters, which can be written in VTK Python, and supports Python scripting. The client/server architecture of ParaView, which supports distributed memory systems on the server side, makes it suitable for visualisation of very large datasets.
Rendering a cow in ParaView. (Image created by Robert Entwistle)