The Visualization Toolkit (VTK) is an open-source, freely available software
system for 3D computer graphics, image processing and visualization. VTK
consists of a C++ class library and several interpreted interface layers
including Tcl/Tk, Java, and Python. Kitware, whose team created and continues
to extend the toolkit, offers professional support and consulting services for
VTK. VTK supports a wide variety of visualization algorithms including: scalar,
vector, tensor, texture, and volumetric methods; and advanced modeling
techniques such as: implicit modeling, polygon reduction, mesh smoothing,
cutting, contouring, and Delaunay triangulation. VTK has an extensive
information visualization framework, has a suite of 3D interaction widgets,
supports parallel processing, and integrates with various databases on GUI
toolkits such as Qt and Tk.

WWW: https://vtk.org/