Normal Map Problem

amaeots · Nov 2008

I've been using normal maps on characters and more organic models but I've been looking into more mechanical stuff recently while building my portfolio and have run into some problems with the normals.

I just finished baking this pistol in both Max and XNormal and both have given me essentially the same problem: the lighting issues from the smoothed low-poly model are still showing through in some areas once its been normal-mapped.

Any ideas how to fix this?

Here's the normal map as well.
http://i45.photobucket.com/albums/f51/rorschach88/normals.jpg

MoP · Nov 2008

Either add more geometry around those problem areas to make the smoothing in the lowpoly less harsh and obvious, or try setting smoothing groups up so that those smoothing issues go away. Then re-bake the normal map.

Squirmy · Nov 2008

set the smoothing groups on the forward facing polys (end of the barrel and trigger guard) to something diffrent than the side facing polys. Break up your uvs according to those smoothing groups. rebake normals

amaeots · Nov 2008

Thanks MoP, I'll give that a shot.

Eric Chadwick · Nov 2008

These errors can be solved if you're using the correct shader. What shader did you use? If a viewport screenshot, try these.

MoP · Nov 2008

Oh, that's a good point. Max's viewport shaders are pretty bad at actually matching the normals/tangents that were baked with the ones they display. Maybe try using a different viewport shader (standardFX should work), as Eric said.

Nikko · Nov 2008

quick normal map question, i notice all the normal map texture sheet posted here, they all have purple BG.
how to do it? because i render mine & it's black in the BG texture sheet. while uv layout is normalized.

is it affect the normal map quality?

MoP · Nov 2008

Most apps these days let you choose what background colour you want for your bake (pretty sure Max 2008 allows this).
If not, just do a Magic Wand select in Photoshop with a tolerance of 0, antialiasing off, contiguous off, and just click anywhere on the black background, then flood fill the selection with 128,128,255 RGB.

Guriamo · Nov 2008

easiest way would be just leaving a small gap between the UVs on the affected parts

EarthQuake · Nov 2008

EricChadwick wrote: »

These errors can be solved if you're using the correct shader. What shader did you use? If a viewport screenshot, try these.

I doubt thats the case here, he may be able to improve it slightly, but the hard angles he has here you just cant do with tangent space, he'll need to separate some of those details off into seperate smoothing groups, or add more geometry.

amaeots · Nov 2008

I tried reassigning smoothing groups and re-baking but it looked terrible on the dividing edges between groups. I had noticed previously that this problem only seemed to occur in the Max viewport, so maybe another shader is the best solution.

Also, the problem areas aren't as noticeable with the wip texture so I've moved past it for the moment.

Nikko - I just render out the normals as a targa file with an alpha channel so I can select out the black background using channels in photoshop.

Chai · Nov 2008

amaeots wrote: »

I tried reassigning smoothing groups and re-baking but it looked terrible on the dividing edges between groups. I had noticed previously that this problem only seemed to occur in the Max viewport, so maybe another shader is the best solution.

Also, the problem areas aren't as noticeable with the wip texture so I've moved past it for the moment.

Earthquake pretty much summed it up in his short post.

But we do this sort of hardsurface work on a daily basis so it's obvious to us - I think if you're serious about doing hardsurface game art, it will pay off to take the time to read more about smoothing errors.
I wrote an article about this - http://www.svartberg.com/tutorials/resources.html

amaeots · Nov 2008

Great Article, Chai. I had neglected to adjust my UVs to isolate smoothing groups so I still had black lines on my edges, but I've fixed it on a couple parts of the model and it looks as if that's solved the problem.

Thanks to all of you replied, you've been a big help.

Nikko · Nov 2008

@MoPthx & amaeots for the explanation

Normal Map Problem

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