The Visualization ToolKit (VTK) is an object oriented software system for 3D computer graphics, image processing, and visualization. VTK includes a textbook, a C++ class library, and several interpreted interface layers including Tcl/Tk, Java, and Python. VTK supports a wide variety of visualization algorithms including scalar, vector, tensor, texture, and volumetric methods. It also supports advanced modeling techniques like implicit modeling, polygon reduction, mesh smoothing, cutting, contouring, and Delaunay triangulation. Moreover, dozens of imaging algorithms have been integrated into the system. This allows mixing 2D imaging / 3D graphics algorithms and data.
ParaView is a scientific visualization application designed with the need to visualize large data sets in mind. The goals of the ParaView project are to develop an open source, multi-platform visualization application, support distributed computation models to process large data sets, create an open, flexible, and intuitive user interface, and develop an extensible architecture based on open standards. ParaView runs on distributed and shared memory parallel as well as single processor systems and has been succesfully tested on Windows, Linux, and various Unix workstations and clusters. It uses the Visualization Toolkit (VTK) as the data processing and rendering engine and has a user interface written in Tcl/Tk and C++.