3D reconstruction software
aka ogre v2 - scene-oriented, flexible 3D C++ engine
FlightGear Flight Simulator: free open-source multiplatform flight sim
Open Source Solid Modeling CAD
An interactive viewer for three-dimensional chemical structures.
LDraw™ editor for LEGO® style digital building instructions.
crossplatform multithreaded object-oriented render and audio engine
Realtime raytracer using SIMD on ARM, MIPS, PPC and x86
Python 3D renderer with wireless display support
3D Without Boundaries
For building cross-platform 3D geospatial apps in Java
rayshade and POV for Mathematica Export + view
Cross Platform Professional Procedural Terrain Generation & Texturing
Growth-grammar related Interactive Modelling Platform
Vivid is a modern C++ 3D engine using OpenGL4+
A shader-based software renderer written from scratch in C89
Vivid Engine 2 is an open source 3D Engine coded using C# and C++.
CSG for jMonkey