The Open Source Virtual Reality (OSVR) initiative, together with the RenderManager module from Sensics, enable immersive head-mounted or through-the-window interaction with 3D geometry.  The system runs on Windows, MacOSX, Linux, and Android and supports rendering in Direct3D, OpenGL, and GLES (including pre-emptive direct-mode rendering on hardware that supports it).

These tools were used in constructing Visual Common Ground.  ReliaSolve is a co-developer of OSVR.