Total Realtime Volume Renderer
- Technical Documentation


This documentation describes the OLD Trevor system. The documentation of the newer version is under construction. This information is dated August 1996.

The Trevor system was designed and coded entirely by Sami Kuhmonen.

At the moment the routine is about somewhat over 2500 lines of assembler code, and about 50kb as an executable. TReVoR uses PMode extender by Thomas Pytel, warm thanks to him.

For background information, the data used in this routine is 256x256x24bit and there are 128 of these slices. I also add a 8bit transcluency data, so the dimensions for the 3D-block are 256x256x128x32bit.

The routine can draw images of the data. You can select clipping planes to left, right, front, back, top and bottom that control the area that is drawn by the software. You can also specify a clipping plane that is always perpendicular to the viewplane and that way you can rotate the head and watch the it getting clipped. There is also a 'skinning' factor that can be used to 'skin' the head. That means you can specify how much you want to take off from the head's surface. That will give you the effect of 'skinning' the head. 3D-objects can also be clipped off of the data, like in the pictures. In the first two pictures I have used a clip plane at top clipping the whole head. Then I clipped a cube off of the head. There is also one clipping plane in the back. As you can see, the routine can do a pretty good job in visualising, and it really doesn't take long!

The latter ones were done in an interactive mode, in which you can cut variable sized balls out of the data. It also includes Phong shading, as the first two only had Larusse shading.

TReVoR does currently Phong-shading without the highlights. I'll add the highlights later when I have time.

The view is currently 2.5D, which means that you can select X and Z-coordinates but Y-coordinate only allows some tilting but not full support is added. This will be corrected in future versions, and then it will be possible to view the head from any angle.

The routine also includes some options that help me trying to make the pictures look better. The first two pictures don't have any kind of a smoothing done, but the routine can do it also.

I will write more information as soon as I have the time and something new is added to TReVoR.

Trevor has been used in one application in a show at Heureka Science Park.

The name Trevor was invented by Marko Laihinen, many thanx toU buddy!


feenix@iqs.fi