Mysterious specular/normal seams

boxsmith

I imported a few meshes from 3ds max into UDK to test out their normal maps. In the last few days I've resolved a whole bunch of problems in my process thanks to polycount, but I can't seem to find anything about this very last defect.

As soon as I enable a normal map or a specular map on my material, I get what look like UV seams on nearly every polygon.



Obviously, my UV layout has no such seams. I don't know what I'm doing wrong. The model looks fine in max.



Where are these seams coming from? How can I get rid of them?

unstoppablex

could be smoothing groups were turned on during the normal baking process, causing it to bake the smoothing group hard edges into the normals, does this happen with the spec turned on, but normals off?

boxsmith

Yes, it does. I baked with 1 smoothing group across the mesh. Wouldn't the texture resolution make the seams blurry if it was the normal map? They're super sharp and conform to the edges exactly.

No textures:



Could something during the export/import process have split these edges in my UV layout?

DeadlyFreeze

Well that's half your problem, you can't just use 1 smoothing group. You need to have a smoothing group per hard edge.

It may look fine in max but that's because the normals are synced up with it, but they aren't with UDK so you get all the crazy shading errors.

You should go over the pc normal map wiki:
http://wiki.polycount.com/NormalMap?action=show&redirect=Normal+Map

boxsmith

Derp. That came up in so much of the stuff I was reading, but it somehow totally escaped me that I need to apply it to my models.

I'll give it a shot tomorrow morning and report back. Thanks!

ZacD

Your smoothing groups should match your UV seams.

16bit

further more, you should have smoothing groups when an angle is over... around 80 degrees. And the UV's should also be broken there.

tristamus

As stated, if you have corners / edges that are 90 degrees to each other, you must have separate smoothing groups or you will have smoothing errors.

What you really want to achieve in an ideal situation, is a separate smoothing group at your hard edges, AS WELL AS where your UV splits are. This will make for a beautifully smoothed mesh with no / very little smoothing errors.

sprunghunt

boxsmith wrote: »

Yes, it does. I baked with 1 smoothing group across the mesh. Wouldn't the texture resolution make the seams blurry if it was the normal map? They're super sharp and conform to the edges exactly.

No textures:

Could something during the export/import process have split these edges in my UV layout?

Are you using FBx to export to unreal? What settings are you using. I've seen some odd triangulation happen using FBx with the wrong settings.

It doesn't look like smoothing groups from the position of the seams.

What does the wireframe look like in udk? How does this compare to the wireframe in max?

Try exporting and importing using ASE. Or try putting an edit mesh modifier on the model before exporting.

Kurt Russell Fan Club

Your problem has nothing to with smoothing groups, though they're some good tips in general.

You need to import your normal map using normal map compression or else the shader will give you bad specular highlights in areas near UV seams. Change TC_Default to TC_NormalMapUncompressed (or one of the other normal map settings). You'll know if a normal map is imported in Unreal properly because it'll be dark blue rather than your normal purple colour. Note that if you re-import the same texture using a new compression setting, you might need to restart Unreal before the shaders update (I got that in older licensee versions).

Example:

Xendance

Kurt Russell Fan Club wrote: »

Your problem has nothing to with smoothing groups, though they're some good tips in general.

You need to import your normal map using normal map compression or else the shader will give you bad specular highlights in areas near UV seams. Change TC_Default to TC_NormalMapUncompressed (or one of the other normal map settings). You'll know if a normal map is imported in Unreal properly because it'll be dark blue rather than your normal purple colour. Note that if you re-import the same texture using a new compression setting, you might need to restart Unreal before the shaders update (I got that in older licensee versions).

Example:

If the normal map has been imported with default compression settings then you also need to change the unpack min values for RGB channels. For normal maps they should be -1. Using the normal map compression setting upon initial import sets the proper values automatically, but not after that first import.