View Full Version : Bump map obscures texture map?

02 February 2007, 03:09 PM
Trying to texture this tire, having some trouble. I first put a cylindrical texture projection on the tire for the tread coloring/texture. This seems to work fine, and that looks like so...

If I render that tire out (excuse the muddy renders) it looks like so:

Needs tweaking but it works. So then, I have a goodyear sidewall, which I was told to make a bump map and attach it to the material. So I added that image and plugged it into the material's bump map. What happens is it seems to cover something somehow, the treads in the tire (which are modeled, not bumped) get obscured. The sidewall also looks really choppy, not sure if I am doing this right. Here's the PPG for the material.

When I render it, I get the following

And the tread is gone...seems like I'm in the ballpark but I am doing something wrong...any suggestions?



02 February 2007, 07:05 PM
I'd start by making the bump map correctly. Black is an indentation and white a protrusion. Most all of that black you have going on should be 50% gray (128,128,128) where there is no bumping. Remember, >50% gray for bumping out, <50% for bumping in.

The tread problem I can't figure out from your screenshots other than to note that you don't seem to have a proper projection setup for the sidewalls, so maybe the tread is grabbing your sidewall bump map. Remember that a cylindrical projection only projects onto the curved side of the projection, not the ends. If I was texturing that just using the tools in XSI, I'd do a box or planar (from the side) projection of the tire, then do a cylindrical sub-projection for the tread.

Also, be sure to specify which projection you want to use with your bump map in the PPG. That's always a good practice.

EDIT* Didn't notice before but you need a proper bump node, not color to vector.

02 February 2007, 09:58 PM
EDIT: Ok figured that out, in order to scale these vertices in one direction vs. all directions, you need to use only one of the three buttons for x, y and z....moving on...will try the subprojection next.

02 February 2007, 10:25 PM
EDIT* Didn't notice before but you need a proper bump node, not color to vector.

Ok, I think I have the projections right. I did the planar first, put the sidewall where it belongs. Put the cylindrical second. None of the presets work, I had to rotate and scale the texture projection manually, but once I did that I at least have the treat covered with the proper texture.

I tried adding the bumpnode, but each time it disconnects the textures - plus how do I add a bump for *only* the sidewall when my texture image has both areas of texture? Below is a quick render and my tree. Do I need two image inputs or something? Either I am making this too hard or it's harder than it has to be.

02 February 2007, 01:23 AM
Hi there. First off, do yourself a favor and download/install the wonderful zbump addon.

I forget the site, but if you search for benr on xsibase, you'll find his profile with a link to his shaders. Might as well get em all.

Guessing that you could either color the tread part 50% grey, so there's no bump. or use 2 different materials. Try duplicating the tire material in explorer (m shortcut for materials.. Have you named your materials? select the cluster, hit 7 and then you can dbl click the material to rename.. Or use the new Material editor. ctrl 7. ). Then select the side cluster (if you don't have a seperate side cluster, select the uvs in the tex editor, and run a script to select the polys (available in the scripts section up above. Search towards the end, cause it's been rewritten). With those selected, Material/Assign and pick the duplicated material in explorer.

02 February 2007, 03:43 AM
Thank you dwig, I do name my materials and do use the materials editor. I will read through that again and see if I can work that out. For the sake of argument, here is where I got up to this point...

I made the planar projection first, with the sidewall, then did a subprojection with the tread, Here is that

Here is the render tree

And the render

So, not sure if this is still workable or if I should instead go the zbump route (which I will definitely try)? The problem here is there is no base texture on the sidewall on which to put the bump on - so I'm just getting the gray. I don't know how you'd solve that, plus I'm using the whole texture for the bump, which seems to be not right.

Thanks for the help so far, btw, appreciate it a lot.


02 February 2007, 07:09 AM
Yet another problem I forgot about but this should set you straight (finally lol). One thing about the XSI bump generator is that it bumps the opposite way of most every other program. Most programs it's black is indent, white is protude. XSI's default generator is the opposite. So for ease of use, just about everyone uses zbump since it bumps the most common way.

Here's the link to zbump.

And here is the setup. Click for larger pic. (

02 February 2007, 02:41 PM
Awesome, thank you very much - I will try this today!

02 February 2007, 03:18 PM
Hmm, I added zbump but where do you find it? I dragged the addon into the app, it shows up in the plugin manager, but it doesn't show as a node under the bump node list...

02 February 2007, 03:53 AM
Hi Pixelmech ive posted a possible solution over at xsi base - Adam

02 February 2007, 10:03 PM
Based on Adam's input, this is where I'm at. I think this real close. I used a BM generator instead of the color2scalar, darkened the ambient light and specular lights on the phong. I still don't understand the bump settings, but it's much better.

The problem remains of the underlying texture on the sidewall though. I'm not sure phong is the best for this, I was thinking I read Anistropic? But it doesn't seem to have a bump input.

I suppose a procedural texture might be good in a case like this...but add lots of rendering time?

02 February 2007, 02:01 AM
Ok, I ended up doing a subprojection - cylindrical for the tread and planar sub for the sidewall. That texture image is just two big squares of each texture. In order to be able to do that, I had to unplug the bump map *and keep the material window open* - that was important, because I found out the hard way if you close it while something is unplugged, she gone next time.

So I unplugged the bump, and was able to do the two texture projections. Then I plugged the map back in and it all seems to work. I need to figure out a better looking texture now (and figure out how to not have the tread stretch so much). Also, the bump looks really artifacty, and I can't figure that one out yet either. No matter what I adjust on the bump settings, that doesn't change. It could be because that is a JPG and it is compressed.

I still think it might be worth try to build a material out of fractals or something instead of using images. I haven't been able to locate anything on line yet as a starting point however.

Thanks for the tips.


02 February 2007, 08:49 PM
still think it might be worth try to build a material out of fractals........

for a tire tread??? Sorry, but there are dozens of tuts on modeling tires on the web, yes mostly for MAX or Maya, but the basic poly modeling is the same and easily translated to XSI. Model the treads, select the sides, assign a separate material to that as you did and you're fine.

If you still want to use a texture for the tread, use displacement instead as that will push out the geometry of the model as bump will never do. Also a square map doens't really work for the tread, as you're unwrapping a narrow cylinder so stretching will occur. Remember math in highschool?? The texture will be a long narrow texture, unless you start using the repeat option for your texture, than you can use the square image and stretching will be eliminated. And try not to use compressed imageformats for textures too.

Hope that helps,


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