long faces in low poly causing baking issues

Aigik

This is a problem I've always wondered about. After I create my low poly, and proceed to bake it, areas with lots of long thin parts parts of the low poly come out really funky in the normal map bake. This doesn't just happen on tris for me, it happens on quads too. Here's what I mean:








As you can see, the distortion is appearing in the normal map. What am I doing wrong here?

Ace-Angel

Cannot see images, try uploading on imageshack.

Ace-Angel

Strange, I also did models like that and issues like that never happened. What did you use to bake?

Also, did you put in support loops for the low poly? Just incase, also try what Dustin said.

CrazyButcher

have you tried the "quality normals" from 3point shader? (since you show viewport rendering, it likely is related to max's broken ts)

imperator_dk

Like CB says it's a tangent space issue between the renderer and the bake. Theres nothing wrong with the distortions in your bake the bake is just trying to counter compensate the smoothing on the lowres mesh against the highres mesh.

You would need to apply a tangentbase corrected shader like the 3point one to get rid of the artefacts on final model.

As a work around for engines without tangent space correction you could bake to a lowres mesh with less challenging smoothing.

However I wouldn't really ever aim for thin tri-fans like that in a mesh, both because of the above smoothing reasons and the extremeties they cause in your bake (which transfers badly to LOD meshes etc.) and for fillrate reasons because rendering long thin tris sucks more fillrate than a more evenly distributed topology does.

almighty_gir

if you're absolutely adament about having the bumps in the mesh, try simplifying your polyflow, something like this might help:

Mark Dygert

You want that distortion in your normal map, it would be wrong if it wasn't there. Think of it like putty in a crack, your normal map will have different height variations that are working to smooth out the surface.

What are you using to display the normals in the viewport? Like CrazyButcher and imperator_dk said you need to change your viewport shader to something that is properly synced. You can also revert to a standard shader and render the scene, which is properly synced by default and will display it correctly, which is a bit of a pain but solve the issue out of the box without the need for 3rd party software (even as groovy as that 3rd party software is).

Scruples

The reason for this is explained here in the normal mapping category.
http://area.autodesk.com/blogs/shane/hotfix_4_3ds_max_2011_3ds_max_design_2011

Optionally you can average the normals of all the vertices which are planar, this would reduce the distortion and make it possible for the normal map to be used on a LOD model properly.
And theres a script here GetVertNormalsFromFace which is useful http://wiki.polycount.com/VertexNormal

Bruno Afonseca

I was getting this same error on a mesh using Xoliul's viewport shader. So.. what should I do about it?

OtrickP

Post the render to texture settings you're using

Mark Dygert

fonfa wrote: »

I was getting this same error on a mesh using Xoliul's viewport shader. So.. what should I do about it?

Have you tried the 3Point viewport shader? What about using the realistic mode in max2012? What about viewing it in an engine like UDK or Marmoset?

In whatever version of max if you render the scene (9) and the distortion isn't there you can ignore it. More than likely the problem your having is just with the realtime viewport display you're using and nothing is wrong with the normal map or the model. Unless of course you've been tinkering with the map in photoshop and managed to hose things up, then you need to learn how normal maps work and how you can edit/enhance them without screwing them up.