Tips on getting rid of Normal Maps seams?

Pioldes

Hello, I'm having a problem that is slightly driving me mad. I've spent all day trying to eliminate the big seams on my model to no avail.

I usually just flip the green channel and I can get it to work, but it does not seem to be working on this occasion.

At first, I thought it was the dreaded 3ds Max Gamma/LUT control that seems to create abominable normal map seams on my models. It was not it. While it is a bit less noticeable, it's still nowhere near perfect.

Anyway, here's how it looks with the raw Normal Map, without modifications: http://imgur.com/XhcrF,kqyHW,JR2zI#1

Then, by flipping the green channel of the upper shell (the one that doesn't light properly): http://i.imgur.com/JR2zI.jpg

Then, by following this tutorial: http://www.andrewklein.net/bh/fix_normalmap_seams.html , I get this (still modifying the upper shell): http://i.imgur.com/XhcrF.jpg

I am lost here. Is there something I'm not seeing? It seems to be borderline acceptable by following the tutorial in some parts, but it still looks horrible in others.

Any ideas?

Pioldes

Oh, it was baked with Xnormal, forgot to tell.

Pioldes

Well, I managed to get it done.

I did the bake in 3DS Max, and I have to seams whatsoever. I do have two weird box-shaped artifacts (like cage artifacts, but completely square, it's odd), but nothing I can't manage.


Leaving this here for other people.

Xnormal is great, but not perfect.

AlecMoody

the guide for removing seams you posted is full of bad information.


Two things- what does the smoothing look like on the object without any normal map applied? Also, what does an all 128,128,255 normal map look like when you apply it?


Baking in xnormal for display in max viewport is pretty much never going to work correctly. Most likely you are going to be stuck with those seams unless you change what software you are baking in or what software you are rendering the game model in. What is the target engine for this?

Edit:
I should add that if you want it to render correctly in the max viewport but dont want to bake in max you can export an SBM file with the tangent basis packaged into the model. Then xnormal will load that tangent basis on the bake and create a much more max friendly result. This gets a little confusing because I am guessing you are using max default/legacy tangent basis which doesnt match the max scanline baker.

Pioldes

It's more of a personnal fooling around project, to be honest, practicing my Zbrush/texture/retopo skills. I plan to try and render it with the Xoliul shader, and maybe ultimately put it in UDK if I ever get the courage to skin and animate it.

It probably will end up as a Mental Ray turntable as a last resort. (Building a better portfolio to get to Uni).

Pioldes

Thanks a lot for the advice^

I'm still a bit new to this whole tangeant business, but I'm starting to get the hang of it. Thanks the internet.

AlecMoody

The issue with your plan is that you are looking to display the model in multiple environments- each with a different tangent basis. Normal maps need to baked with the target engine in mind. I think the easiest pipeline for max users is to enable qualified normals rendering (assuming you have max 2011 or newer) and then bake with max scanline. Alternatively you can use the 3 point shader.

I have a bunch more info on baking normals in a 3dmotive video.

http://www.3dmotive.com/training/3ds-max/baking-tips-and-tricks/?follow=true

Also some information on enabling qualified normals in max and exporting them for use in UDK:
http://www.3dmotive.com/exportingqualifiednormals/

mmikkelsen

Are you getting the same seam when you view the model with normal mapping in xNormals 3D viewer?

If you are then you "might" have an issue worth reporting.

If you do not get a seam in xNormals viewer then the problem is your own fault (or your programmer's).

Pioldes

I wasn't aware of that, that is very useful, thank you again!

I'll definitely look into that

Well this was a great first impression of that forum.

mmikkelsen

You might want to take a look at this description of tangent space and the problems people often encounter.

http://wiki.blender.org/index.php/Dev:Shading/Tangent_Space_Normal_Maps

Pioldes

Thanks mmikkelsen, this is plunging me a bit out of my comfort zone when it comes to the understanding of software, but I think this is a very good thing.

I will probably come back soon with a few screengrabs of the finished project. Now that my normals problem is out of the way, it's fun time until the end.