View Full Version : Bump map shadowing?

10-10-2004, 03:43 PM
For some time now I have wondered if Lightwave will render shadows for bump maps, and just recently I tested it with a simple scene.

I took a simple plane, subdivided it in Layout with a setting of 64 (therebye creating a circle) and added a displacement map using the Veins procedural making the displacement high causing a steep mountain type terrain. Using this I switched on Ray Trace Shadows within the Render Options and rendered out an image just for the sake of seeing what the shadows would look like with real geometry.

Then I copied the procedural texture and deleted the displacement, took it into the Bump channel in the Surface Settings, and used it as a simple bump. Rendered again and no shadows for the bump map.

I was just wondering if I am forgetting something or if Lightwave just doesn't render shadows for bump maps. And if it doesn't I was wondering if other applications do...or if this is something that no program has been able to render yet.

Thank you.

10-10-2004, 04:11 PM
Nope, unless you have real geometry you ain't gonna get shadows. Some packages now have sub-pixel displacement surfaces, which are displacement maps on steroids, and these should cast shadows I imagine, but I'm not sure...

10-10-2004, 05:43 PM
No. They all fake it when bump mapping so nothing to cast.

10-10-2004, 06:25 PM
My understanding is that with Pixars Render-man they have a solution that has sub pixel displacement mapping. Itís not really bump mapping but a replacement for bump mapping. Iíve never used it personally but from what I understand it's fast and because it creates geometry on the fly that geometry would raytrace, so you would have shadows from your bump maps. Once again Iíve never used this software but there is an article here.


If nothing else, itís fun to see where the different companies rate in the film industry.

10-27-2004, 04:20 PM
What Dodgy and spud are referring to is not sub-pixel displacement mapping. Lightwave *has* sub-pixel displacement mapping. Renderman calls what they are referring to 'micropolygon displacement mapping' and Maya calls it 'microtesselation' or some such. Both actually subdivide the polygonal surface of your object They can look very nice, but can also create alot of additional geometry and send your render times into the stratosphere.

10-27-2004, 04:26 PM
The way I understand the other's implementation, and some of their jargon, is that they displace ONLY where needed; that is to say, they subdivide 'smarter' than ours.
Ours sub'ds everywhere; theirs on the corners and edges where more detail is needed.

An old program called Organica did this in 198x. :)

10-27-2004, 06:04 PM
Actually sounds very cool, it would be nice to see that kind of technology in a LW update someday, even if itís not entirely necessary.

10-28-2004, 07:33 PM
Thank you for your replies. I just figured this would be another great leap for CG along with SSS. I think that this is one of the few of the last things to add in order to make fully realistic renderings through fast paced creation. I know actually subdividing it will give you it but right now (for me anyway) the technology is not fast enough to edit in realtime with something like this (unless I am missing something). Not simple meshes, I mean full blown displacement, where you use a texture map for the displacement of pores in the skin. Even though they are really small, close-ups could really prove the reason behind it. Even though the shadows would be very unnoticeable it's that small amount that makes a big difference if you know what I mean.