This is a set of advanced samples for the NVIDIA OptiX Ray Tracing Engine. They assume some previous experience with OptiX and physically based rendering, unlike the basic tutorial-style samples in the SDK directory of the OptiX 4.0 distribution. They also use some different libraries than the SDK samples; GLFW and imgui in place of GLUT, for example. This means you cannot generally copy one of the advanced samples directly into the SDK, and vice versa.
Some samples, like optixVox, are new. Others used to ship in some form with OptiX prior to version 4.
For requirements and build instructions see INSTALL-LINUX.txt or INSTALL-WIN.txt.
Technical support is available on NVIDIA's Developer Zone, or you can create a git issue.