After working with the terrain editor today I found something interesting. Heres a simple test. Place a sphere in an empty scene. Set the atmosphere to Default sky. Edit the default shader. Make it reflective so it is easy to see the effects of the bump map. Then under bump apply the noise factory. Notice that when the default mapping of Local is selected it works fine. Switch it to Global and there is no bump. No matter what scaling settings you set, there simply is no bump. The other options dont affect it either. Take the same texture and apply it to the color channel as a mixer between two colors and it works in the color channel producing an alternating color pattern based on the noise. But it will not work in the bump channel. This seems to affect all functions that have a global setting under bump. Anyone else confirm this? Or is this something wrong on my end? Thanks, Donnie

Donnie,

It's a known issue, bug, limitation, whatever. Shaders driven off of Global coordinates do not work in the bump channel.

Regards,
Eric Winemiller
Digital Carvers Guild
3D plug-ins for Carrara
http://digitalcarversguild.com

Thanks for the response Eric. Do you know how long this limitation has been known? Seems strange that it only affects the bump channel. Thanks, Donnie

Donnie,

The problem has been there as long as I can remember even back into the Ray Dream days, and I think I did make a point of reporting the problem back in the c1 days. Most of the noise based shaders don't do their own bump map so the renderer has to pick spots around it, query the shader, and then figure out how the normal is changing based on those surrounding samples. I suspect that it must be hard or impossible to figure out where to take those samples for shaders based on global coordinates.

Here's where I get to say, "I'm glad you asked the original question". The new plug-in we just released, Velout has a solution. Included in Veloutis a tool called Filter. Amongst other things, Filter will calculate the bump for child shaders, including noise shaders set on Global coordinates ;). You can check out Veloutand download the demo from

http://www.digitalcarversguild.com/products/veloute/

If you have any other questions, please let me know.

Regards,
Eric Winemiller
Digital Carvers Guild
3D plug-ins for Carrara
http://digitalcarversguild.com

Yeah I saw your announcement about the new plugin. Looks very nice. First on my list of things to purchase is the PowerPack. After that I will look into getting the new plugin. As far as global coordinates with bumpmapping I know its not impossible for it to be done. Lightwave does it. Must be something that is harder to program or requires a different approch to the renderer as you suggested. There are some situations where it comes in handy, cant remember when I have used it, but I know I have. But for now I will just work with local. Either way, if it doesnt work, they should remove the button from the options. Donnie

Eric, BTW, after taking more time to look at the new plugin it is even more impressive than I thought. Looks like it could solve a lot of interesting problems with regard to bump mapping. Looks good enough from a distance to simulate true displacement mapping. Really gives more depth than standard bump mapping. I am referring to the examples using the filter shader. Nice work on that one. Donnie