View Full Version : Going nuts with turning weight to bump

Thomas M.
12-31-2006, 10:38 AM
I created a weight map on an object (simple transition from -100% to 100%). I use this weight to create a color texture and influence the diffuse and specular levels (all with nodes). Works like charm.

At a certain percentage of the weight map I need to create a bump. I tried everything I could think off with bump maps and normal operations. But in the end I don't succeed in creating a bump with the weight map. I just need a small elevation along the certain percentage, like a terrace. But how?

Seems to be really easy, but obviously it isn't at least for me. Anybody a guess?

Thanks in advance and a happy new year to everybody.


12-31-2006, 10:53 AM
Use the weight map as an alpha channel input for the bump map? Should work though I've not tried it just now.

Thomas M.
01-01-2007, 04:24 AM
The point is that my weight map needs to be turned into a bump map itself via a gradient. So, let's say between 50% and 55% percent of the weight map I want an elevation line. Coloring this line via a weight map/gradient is no problem, but to create a bump the same way seems to be impossible.

Using the weight map/gradient as an alpha for another bump map does work, but that's not the effect I'm after as it looks completely different. I just don't know why I can't turn the scalar information of the gradient into a bump or normal relief. Even DP's Scalar2Bump node does fail.

Isn't there a way to raise the normal via the weight map/gradient? I have to translate the bump anyway into normal info the feed it dirrectly into the shading node.

Help is urgently needed!

Thanks so far and I hope all your brain cells made it into the new year, at least most of them.


01-01-2007, 06:01 AM
TrueArt's Modeling Pack http://modelingpack.trueart.eu has VMapManager tool that has option to bake weight maps to images (or load weight map, color map from image). You can do whatever you want with this image f.e. use as bump map.

01-01-2007, 07:33 AM
Scalar2Bump node works only with an input node
which works with the position of spot currently for
mapping image map or procedural texture, but vertex map
like weight map are not evaluated with the position of the spot,
So, yes here you should bake your weight map as an image map.


Thomas M.
01-01-2007, 07:50 AM
That's unfortunately not possible due to the complexity of the object. Isn't there a way to just use the weight map in combination with something else to create the impression of a relief or crease, etc.? Works as an input for Spec, Dif, Color and so on like charm. I don't want to go bonkers so soon this year.

Cheers, mates.

01-01-2007, 08:00 AM
What a bump map basically does is bend the surface normal (-> change the direction of it).

You could use the gradient node to define an area where you want to bend the normal, and use the output to control/weigh the multiplication of your proper surface normal with another, arbitrary normal. The question would then be: Where should this other normal point to?

To derive that (target) normal for a bump map, LW usually samples your texture around the currently shaded spot (-> evaluate it for positions around the current spot) to create small gradients which in turn define slopes. The direction and steepness of these slopes (along x,y,z) thus define the orientation of the target normal.

In the case of using a weight map, that would mean sampling around the currently rendered spot, and this is something LW doesn't do presently (for weight maps), so baking is the only solution I see as well (except for custom coding).


01-01-2007, 08:20 AM
Have tried a (fake) bump effect with weight map,
depends if your mesh is fine enough, multiply
the output of the weight node by a math node (ie x10),
connect it to the bumpamp input of a procedural,
like 3D Turbulent Noise increase its scale value to 100 meter.
Very approximate, but you will get some bumpness.


01-02-2007, 01:23 AM
Hi Thomas and everybody

If I understand the problem, here is an answer :
Use a gradient, based on the weight map to create a scale. Use this scale to scale a bump procedural and connect the result to the bump input of the surface. See the attached files.

Hope this could help.

PS: If I know that a lot of people could be intertersting in, I plan to develop a site in 2007 for tip and tricks for lightwave, with free and not so free content. Specialy modeling and surfacing. The idea is to have a lot of small tuts, each on a very specific subjet (Like the one of this thread) . So, every feedback could help to take the decision. I know that I will have good feedback for free content but what about paying ?!!!