Need some bump/normal help.

Gibbage

I have this model im making in 3DS Max (2008) and im first making a high poly model, then baking it into a low poly model for live rendering (Crysis). Its a hard surface model (space ship) and I decided to draw in the panel lines and rivits using normal bump (height) mapping. It looks great, but wont render into normal maps correctly.

Here is the high poly mesh (on the left) with the bump map applied, and the low poly target mesh on the right.



Everything looks find and dandy till you zoom in were the UVW map has seems.



You can see were the panel line goes from one UVW seam too another, the bump map gets inverted! This seems like a small problem, but it shows up badly on the normal map once its rendered out.

Here you can see the UVW and bump map.



This is with Max's Render to Texture and using Scan Line. I tried Mental Ray but got the same results. Is there any fix for this? It seems like a really stupid thing for it to invert the shadow over a UVW seam! Normally I just paint panel lines in Photoshop using the Nvidia filter or Xnormal's HeighttoNormal, but I dont wanted to try a more detailed route.

Any help would be great!

SpeCter

Any possibilities to see the UVW Map?(damn i´m totaly blind nevermind this)
Did you try to use a Custom Shader like Xolius Shader(sorry for misspelling)?

Eric Chadwick

Some info in here.
Why you should NOT use 3ds Max's normal-map bakes in games!

Eventually I'd like to condense the info into here.
http://wiki.polycount.net/Normal_Map#TangentBasis

mLichy

I'm guessing it's from compression, because your UV's are at an angle, or your UV's are stretched in that area, or a combo of the two. Also make sure your Uv's aren't inverted in the UV editor.

I disagree about using max for baking maps, I've had no issues using max over other programs. I use max at work, along with alot of other ppl, and it's fine.

MoP

mLichy: It might seem "fine" depending on what engine you're using (ie. maybe one set up to match Max's renderer tangents, although that's unlikely), but tests have conclusively proven that there's a mismatch between Max's renderer tangents and viewport tangents, which in 99% of cases also means they don't match your target engine. Just because you haven't noticed anything doesn't mean it's not wrong... you should probably read that thread fully if you haven't already

Gibbage

I think there is a misunderstanding. The seam is from the height map, not the normal map, and its transfering onto the normal map. So Its not how the normal map is generated at all.

You can do a test on your own computer. Make a sphere, and apply a plane UVW to it, and drop a bump map of a simple line. If you edit the UVW, detach the top half and bottom half, and move the two peaces, the seam will show up. The texture didnt change, but it suddenly flops the shadow once a seam is introduced. Here is what it looks like.



This object does not have a normal map on it. Only a basic bump map with a line. The bump map somehow gets inverted over the seam, and thats the problem im having.

The more and more im looking into it, the more it seems that its just not possible to paint in panel lines using a bump map. It just seems 3DS Max cant transfer the bump map over seams. I guess I will need to paint them in Photoshop. I really didnt want to do that because it does a lousy job at it. I just cant find any samples were people have used this technique at all, of painting in details using height map, and baking it into the normal.

mLichy

Mop: I did look at that thread, and the normal maps from Maya, xNormal and Max all looked identical from what I saw as I was looking through it. I know the normals don't display the viewport fine, but I don't usually check them in there, at least the seams.

MoP

mLichy wrote: »

Mop: I did look at that thread, and the normal maps from Maya, xNormal and Max all looked identical from what I saw as I was looking through it.

Sorry for being off-topic, but you did see the images where someone did a "difference" blend in Photoshop showing the differences between the Max, Maya and XNormal bakes, right?
They are not identical. If you think they are then you must just have glanced at them and not actually done any sort of empirical comparison...

As for the question in this thread, it seems like Max isn't doing a very good job with the bump map display in the viewport. Does it look similarly broken in an actual render, or is it just the realtime display that's wrong?

Ben Apuna

Rather than using a bump map, could you use a displacement map instead? That way it will displace the actual geometry before rendering the details to the normal map. I don't think displaced geometry details will invert over a UV seam.

Gibbage

Its an idea, but will require a massive ammount of polygons to do it. I will play around with it, but it seems like a huge load for a work-around.

Also, lets not turn this into a Max vs Maya vs Xnormal. Each has there own way of doing things with there own unique qualities and drawbacks. I have used xNormal a lot, and it just does not work well for hard surface normals since it has problems keeping smoothing groups. Also, there is no way to add a bump map in xNormal.

Gibbage

MoP wrote: »

As for the question in this thread, it seems like Max isn't doing a very good job with the bump map display in the viewport. Does it look similarly broken in an actual render, or is it just the realtime display that's wrong?

Both real-time and render show the flaw. I havent tried Maya or any other programs since I dont have them. Also, Vray and Mental Ray do the same thing. Leading me to think its part of the shader and how max handles bump mapping. Ill try using a Vray shader mat, but Vray does not support projection mapping.

Gibbage

The displacement works, sorta. Its just too difficult to get the mesh resolution needed for it. In Mental Ray, you can have the displacement in the shader, but its still having problems getting the resolution. The results look very blocky.

MoP

Maybe you could try converting the bump map into a normal-map using the Photoshop NVidia filter, or Crazybump (or the XNormal Photoshop filters work too), then using that instead? I have a feeling it'll work better, and won't require crazy huge subdivisions like displacement does.