Cylindrical shapes normal map baking, newbie problems

alexk

I'm a newbie trying to learn normal map baking, I'm using Maya 2008 and for the most part it's going well except when I try to bake cylinder type shapes. I've been using Ben Mathis's normal map workflow http://www.poopinmymouth.com/tutorial/normal_workflow_2.htm to help me but I still can't seem to get the same results as his cylinder example (see link).

These are the steps I've been taking...


1^ this is my high poly and low poly cylinders. low poly is 16 sided.


2^ I place the low poly on top of the highpoly. I think my placement should be fine, but correct me if I am wrong. The red shaded is the search envelope for the baking. In Ben's tutorial, it's reffered to as the cage which I guess is 3DMax's term. I think what I am showing with the red shaded is the same thing but again correct me if I'm wrong. I've placed the top and bottom of the envelope very close to the top and bottom of the high poly model, encasing it but not touching it.


3^ This is how the low poly looks after the bake with the normal map applied. On the bottom there is weird bumpy things. It's also on the top but not as obvious.


4^ This is the resulting normal map generated which is not as clean as Ben's (below screen)



How come my normal map isn't coming out as clean as in Ben's tutorial? Also, I'm still learning so if there is anything I can improve in my steps or anything at all, please feel free to chime in!

Mark Dygert

Yup that will always happen, the best you can do is to get the top of the cage, as close to the high poly as possible. Normally this requires clean up in photoshop. I just grab one row of verts from the closest clear row and stretch it over the effected area.

Really if the only difference is a few more sides, and a beveled edge, your high could be your low.
Some good reading on the subject: http://boards.polycount.net/showthread.php?t=50588

CheeseOnToast

Vig, Maya doesn't use cages the same way as Max. They don't control ray direction, only ray length, so poop's cylinder trick won't work. The most sure-fire way is just to add a bevel to the edges around the cylinder cap.

Joao Sapiro

use xnormal, way better to make perfect normal maps, even from cilindrical.

Mark Dygert

Seriously? You can't tweak the cage? Come on guys, I like your software but make it usable. Just when I think its safe to switch I find out stuff like this. Oh well maybe next version =/

I think you can specify a mesh as a cage in XNormal can't you? I guess beveling would clamp the effect some more to the point it isn't noticeable?

I think cheese is onto something, the low poly mesh you use to do the baking doesn't need to be the final mesh.

airbrush

I have a different method that I use, here is a link to a previous posting and a tutorial I made with the same issues.
http://boards.polycount.net/showpost.php?p=761510&postcount=8

EarthQuake

you know really, these types of "artifacts" or "errors" that you see there, i generally like to have, if you just have the rigid straight line its still going to look like a lowpoly, 12 sided object from all angles, and with this from most angles it will actually look better. As long as you have enough sides to not have crazy errors(like ben's 6 sided mesh, which is gonna look like ass no matter what you do) i'de take the curved version.

Slum

The 'wavy' lines actually look better if you are looking down the length of the cylinder. with the straightened version, you will see the edges of the cylinder start to facet and the highpoly illusion is gone.