Rays missed during normal bake

gannonroader

Hey guys, I'm finally buckling down and going a little more in depth with baking a high polys normal map onto a low, and although i've learned quite a bit, I still have miles to go. One problem that seems to be quite persistent with me is rays missed. I checked my cage over and over, I double checked my smoothing groups, etc, etc, but i'm STILL missing rays every time I bake a normal. And sometimes it's pretty extreme. I can't seem to find any good answers as to what's going on, and these forums have never steered me wrong so i'm hoping someone can steer me in the right direction.

http://s647.photobucket.com/albums/uu192/gannonroader/?action=view&current=normal_mess.jpg&newest=1

Here's a look at the normal map. I know alot of you are going to say my cage isn't pushed out enough, but I checked at least 10 times, and adjusted and shifted it all about, but i'm still getting these missed rays. I'd love to hear some theories as to what's going on so I can move forward with this exercise.

throttlekitty

Since specific triangles are missing there, I'd wager that some of them are facing the wrong way on your low poly. I'm not sure how to check/fix this in max though.

gannonroader

Yeah, it would look that way eh? I know theres a "normal" modifier that can unify the normals so they're all facing the same way, but when I look at the model, the normals are all facing the same way. I'll give it a try.

***UPDATE****

That didn't work. Normals are all facing the right way.
Also tried "cap holes" to make sure there wasn't some funk going on where it was casting rays maybe through the deleted faces in the back. Still no change.

throttlekitty

Normals and face direction aren't really the same thing (you can have a face going one way with the normal going the other). I know Maya's function for flipping faces is 'reverse normal', thought I'd mention it in case that's not the right function

totally unrelated edit: I see photobucket now has a little service that auto-links images to products. I could get a coffee mug with your image there!

Mark Dygert

Select the mesh, right click, go to object properties and turn on "backface cull". This will turn the back faces of all polygons transparent making it easy to spot the ones that are flipped.

The normal modifier doesn't unify normals it only reverses every face, so what was flipped is correct, but what was correct is now flipped.

Once you find the flipped faces you go into edit poly > polygon model and use "flip".

If it isn't flipped faces it could be control cage, try resetting it and pushing it back out (using the options in the projection cage's modifier). Or it could be the ray depth is too shallow if you aren't using the cage.

gannonroader

No, it 100% has a unify normals toggle that you can click off, and it also has a toggle that "flips normals". If you toggle "flips normals" off and "unfy polys" to on, you get the same effect. as

Oh, I should also mention i'm using max, and the cage looks pretty sweet. I really can't see any problems.

DarthNater

Are you using Mental Ray to bake? If so, I had an issue like this before. All I did was scale my LOW POLY model down by -.01 in all directions and it seemed to fix it. I mentioned this in another thread and it worked, but they had to scale down by a little higher value.

gannonroader

hmmmmm, I'll give that a try. Do I select the object as a whole, or each individual piece?

DarthNater

as a whole, and again, make sure it's your low poly.

gannonroader

Thank you so much man, that worked wonders. I never would've figured that out myself.

DarthNater

SWEET I FINALLY HELPED SOMEONE! lol Mental Ray has been picky in the past few versions of max, I don't know why?

Mark Dygert

Oh yea, it factors in the low poly in the Mental Ray AO bake too, totally retarded. I normally go down to element mode on the low poly and hide everything just before I bake.

DarthNater

Vig, can I have this victory to myself please! HAHA Good info though, maybe that will keep me from fighting with MR.