External renders can be used to create a 3D view of higher quality. The POV-Ray Plugin provides a scene export to the POV-Ray format which makes it possible to use the free ray-tracer POV-Ray as an external renderer, see the POV-Ray manual. The resulting image is directly shown in GroIMP's 3D view.
POV-Ray is a free ray-tracer. The POV-Ray plugin defines an export of a 3D scene to POV-Ray's file format, this can be used to obtain high-quality images of scenes modeled with GroIMP.