GRASS (the Geographic Resources Analysis Support System) is a software raster- and vector-based GIS (Geographic Information System), image processing system, graphics production system, and spatial modeling system. It contains many modules for raster data manipulation, vector data manipulation, rendering images on the monitor or paper, multispectral image geocoding and processing, point data management and general data management. It also has tools for interfacing with digitizers, scanners, and the PostgreSQL, DBF, and ODBC connected databases. GRASS operates on all common operating systems.
Jmol is a Free, Open Source molecule viewer and editor. It is a collaboratively developed visualization and measurement tool for chemical scientists. Jmol is an active project, and there are new features being added to it on a daily basis. Users are encouraged to modify it to fit their needs and to contribute their changes to the project.
Doom was the classic 3D shoot'em'up game from id Software. PrBoom is a game engine for playing Doom levels, which runs on both Windows and Linux/Unix systems. It uses the SDL graphics library. PrBoom a very faithful Doom port, with great effort taken to be compatible with as many original Doom levels and demos as possible.
Ayam is a free 3D modelling environment for the RenderMan interface. It features good RIB export, CSG (all RenderMan primitives supported), and NURBS modelling. Features instancing, arbitrary number of modeling views, object clipboard, independent property clipboard, n-level undo, console, and Tree-View with Drag-and-Drop support.
The Interverse is the evolution and combination of the Web, chat, instant messaging (IM), and voice communication. It is not just a graphical user interface (GUI), but an immersive user interface (IUI). The Interverse is a virtual universe running on top of the Internet. It uses the Crystal Space 3D engine to render the user's view of the world.
OGRE (Object-Oriented Graphics Rendering Engine) is a class library written in C++ designed to make it easier and more intuitive for developers to produce games and demos utilising 3D hardware. It exposes a number of useful objects allowing you to create and manipulate a 3D environment and render it to your specifications, while removing the unnecessary complexities of the underlying system libraries like Direct3D and OpenGL.