Gelder et al. have implemented orthogonal and perspective
projection that produces high-quality images at speeds approaching two orders
of magnitude faster than existing techniques in their paper of 1994
[11]. They add stereo projection in their implementation other than
orthogonal and perspective projection in their 1996 paper [12].
Besides, they include a light model in their implementation. This
implementation, called Voltx. They claim that Voltx could improve
the performance by about a factor of ten and produce high-quality images
comparable to ray-casting at nearly interactive speeds on workstations with
hardware support for 3D texture maps.