The upgraded background tag supports a variety of background types, including a single flat color (previously skycolor), image cube (previously srcfront, srcback, srcleft, srcright, srctop, and srcbottom), photosphere (a single image designed to be displayed on the inside of a sphere), and device camera (if available). The environment (or back) camera is preferred; however, XSeen will use either. The originating HTML page must be delivered via HTTPS for this to work (W3C requirement). You can dynamically switch between the various types and background images.
This change is a backwards incompatible. The previous attribute skycolor is now color. This is all documented in the background tag.
The working example is available. It uses the Avenue of the Giants photosphere.