The VR Controls panel allows to control the background sky, the terrain, and the navigation speed.
The radiobuttons at the top of the panel allow to select the surrounding skybox, consists of six images mapped to the faces of an infinitely large cube. The skybox ist used both as a background scenery and for reflections on surfaces.
The snow and desert skyboxes are artificial landscapes generated using the terragen software. They are taken from the wadfather website, where 552 such skyboxes are freely available. grace cross is from a Siggraph course by P. Debevec and is made using photographs.
The custom radiobutton enables a load button that brings up a file browser where you can provide your own skybox as a zip-file with six images. Such files can be downloaded for example from wadfather or here.
By unchecking show sky one can also work with a uniformly colored background, while having reflections on the content geometry.
The terrain panel allows editing the appearance of the terrain. The Scale slider below the different textures can be used to scale the terrain texture.
The slider allows to change the navigation speed of the WASD navigation.