Normal mapping help needed!

[schuubars]

Which sort of Normal map do you have exported?
Tangent Space or Object Space ?
Because only Object Space maps works with the shader.

[Pancho]

Well, it's object space, the really colorful maps. I realized that you can change the maps in PS so that the normals change and therefore the look of the model. But that doesn't help. My point is: Do I have to convert the maps in any special way or what kind of checkboxes do I have to click. The defaults don't seem to work with LW. Or the direction of my light gets screwed.

[schuubars]

Hmm can you post a screenshot ?


I'ts not primary for normal maps, but export(with the uv issue) from zbrush2
http://www.stevewarner.com/Tutorials/zBrush/zBrushTut.html

[Pancho]

Man, do I feel stupid. Made a test with a simple cube the other day and could swear that it's only flipZ and flipVert you have to do that LW eats your maps. Finally realized that it's me who flipped the model during work some days ago, but not the zbrush model. Therefore the lighting got srewed up all the way long while trying to get some decent results.

But now it works. Thanks for the support.
Pancho

[flinder]

pancho, i'm having the exact same problem, but i'm not too clear on why it happens or how you fixed it, so maybe you can help me with this:

i flip the normal map vertically and invert it before bringing it into lightwave. is there anything else i need to do? the map works, it just looks as though the light is hitting my character from the wrong direction.

[Steve Warner]

Flinder, try rotating the model 180-degrees in Modeler. I don't know if this is what Pancho did, but it seems to work for me.

**EDIT**

Well, it seems to work, but if I remove the Normal Shader, the light still isn't exactly oriented.

**EDIT 2**

Got it. See below.

Steve

[Steve Warner]

Okay, now I feel stupid too. From the manual page 199:


"The Preferences Import/Export menu contains five switches for flipping maps when they're generated. Use these to make sure that zBrush's maps match your rendering engine's needs."

Here are the prefs that need to be set. Once activated, the normal maps generated with zBrush will work fine with the Normal Map shader.

http://www.trinitymediainc.com/Help/zbrushnormalprefs.jpg

[flinder]

excellent, thank you. that's been driving me nuts for a week.

[Pancho]

Hi guys! Didn't check the forum for a few days so just came across my old thread. I wonder if it's correct to mirror on the x-axis too. So far I thought you just need to choose flipz and flipvert. Will give it a try. But you see the difference pretty fast if you compare the non-normal-mapped object with normal-mapped one. Light direction will look wrong. Choose a high specular and glossiness value. You'll be able to recognize the light direction much easier by looking for the small hotspot.

But I do have some questions too. I am just about to finish a project with a giraffe and tried to use diplacement-mapping and normal-mapping. The difficulty is that I need to use Sasquatch. Funny thing is that I have the feeling that bump maps don't work anymore. Is there anybody out there who got some experience how to add small detail to a sasquatched surface? I'll need to do a horse soon and would like to now how to show the veins beneath the sas-skin.

P.S.: You can do some pretty neat stuff by using Sas.

Cheers
Pancho

[Steve Warner]

Hi Pancho,

If you're still seeing a change in the object's light position/rotation when you turn on/off a normal map, you should definitely try flipping the normal map on the x-axis (or duplicate the settings in the previous post). I think you'll be pleasantly surprised with the results. Check out the image below:

http://www.trinitymediainc.com/Help/Comparison.jpg

This model can be rotated in any direction and it will respect LightWave's light orientation. If you've already generated your normal map, you should be able to achieve the same effect by inverting the R and G channels in Photoshop.

With regards to your feelings about the bump channel, you're absolutely correct. The ATI normal map shader plugin disables the bump channel altogether, which kind of makes sense seeing as the normal map is just an advanced type of bump map.

Technically speaking, you should be able to get the most accurate results by using a Displacement map coupled with a bump map (as seen in the second image above). The displacement map will actually move the geometry while the bump will help bring out the subtle textures. The problem with this approach is that it requires you to really jack up the subpatch level for rendering and that results in longer render times. The normal map bypasses this by allowing you to simulate high-frequency details on low-poly objects. But those details don't really exist and if you have large changes (such as protrusions or severe indententations) they won't show up in the object's profile and they won't cast shadows properly.

You can combine the normal map and the displacement map, but you probably won't gain much. And if you really need to use the bump texture for other things, using a displacement with the same 16-bit greyscale image also used in the surface's bump channel should give you great results.

I'm looking forward to seeing your next project!

Cheers,

Steve

[Pancho]

Thanks Steve,

good explanation from you as usual. I tried the high poly approach with the giraffe, but everything slows down so much with SubPLevel > 10 (with my model). So I did need to stop at some point. My only concern right now is making Sasquatch work with surface detail which needs to be seen. If you have a look at a horse for example, it does have a very dense fur which (at least in the summer) sticks to the surface (Anybody a shader?). By doing this it does not hide all the veins beneath the skin. You can see them. Usually that's something you'd model by using a bump map. But I guess Sas doesn't take care of bumps. So I wonder how to have a fur on my animal AND detail. Showing veins with normal displacement is pretty shitty in terms of rendering times. I worked a bit with the Velvet shader, but couldn't figure out how to come up with a nice bump map which looks like a short fur (Fur! Not velvet on the sofa! :). Then I could probably mix Sas with a shader and use bump maps with the shader.

Also I did have the impression that the brdf shader is able to fake the specular reflections on a surface like fur quite good. Probably not physically correct, but who cares.

I guess that's one of the big steps in the next few months. :hmm:
(Except from modeling a character, a horse, cloth , etc.)

Well, I hope I'll be able to present my giraffe as quick as possible to the forum. I'm just waiting for some reactions for the last changes already done.

Cheers
Pancho

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