Normal Map Baking Problems (xNormal)
polycounter lvl 10
Hey all,
I have been working on a cannon for a pirate ship and so far I have; created the low poly in max, given it a UV unwrap, taken it across into Zbrush and given it a high poly sculpt version, but now when im trying to combine the low poly and high poly in xNormal im getting strange errors in the normal map bakes.
I have divided up the model and import the pieces separately as opposed to one giant mesh, but these are the results I get on this particular piece and I can seem to find the source of the problem. I suspect it could be something to do with my Unwrap, my exporting options from either max or zbrush, or something to do with the pivot or placing in the world of both meshes? They seem to sit perfectly on top of each other in the max viewports. Apart from the obvious artefacts the whole map seems very harsh with those pink sections also, any help would be very much appreciated.
Thank you
I have been working on a cannon for a pirate ship and so far I have; created the low poly in max, given it a UV unwrap, taken it across into Zbrush and given it a high poly sculpt version, but now when im trying to combine the low poly and high poly in xNormal im getting strange errors in the normal map bakes.
I have divided up the model and import the pieces separately as opposed to one giant mesh, but these are the results I get on this particular piece and I can seem to find the source of the problem. I suspect it could be something to do with my Unwrap, my exporting options from either max or zbrush, or something to do with the pivot or placing in the world of both meshes? They seem to sit perfectly on top of each other in the max viewports. Apart from the obvious artefacts the whole map seems very harsh with those pink sections also, any help would be very much appreciated.
Thank you
Replies
(just a little guess.. ray distance?)
Here's a shot of the high poly, the low poly and both combined in 3ds max. I have tried several different timings for the ray distance calculator within xNormal from 5 sec to well over a minute with no change in results, its almost as if the normal baking is too harsh and strong if that makes sense?
Im also concerned with those harsh contrasted areas of pink showing up in the original normal map shot.
could you just make a quick bake with a cage?
Do you mean make my own cage in max? I thought xNormal kinda took care of that.. Thanks for the help btw!
Hello, I thought that the low poly mesh should have all smoothing groups cleared? Or be 1 snoothing group? I was also told to try the 'average normals' option in xNormal which doesn't seem to affect my bake..
Thanks for chiming in!
you can create one in max and in xnormal. You have to make sure exporting and enabling it in xnormal though.
Anyhow, xnormal allows you to set ray distances without cage but you are obviously doing something wrong or it's something else. if you have the exact same result with a cage it could be magic but I guess you just haven't set the correct min / max ray distances for your lowpoly model in xnormal
also you can bake a ray-miss map to better highlight these areas
Smoothing groups are somewhat dependent on how you plan to view your model in engine. If it's flat lighting, smoothing groups don't matter. However, if you are baking normal maps there are some guidelines you should follow to improve your bakes. There are exceptions, but generally the same steps are followed when preparing a model for normal mapping.
1) UV islands should each have their own smoothing group assignment so smoothing splits fall on the same edges as your texture seams.
2) If your model contains harsh corners that are exactly or close to right angles, a smoothing group split is required for proper normal map baking. This is due to the resulting averaged vertex normals trying to bend light across two surfaces that would be realistically impossible. Consider chamfering these edges instead if you can afford it.
3) If you are forced to create a smoothing group split, also split your UV island to match.
4) Give your UV islands sufficient breathing room from other UV islands (they shouldn't be touching).
5) If you can help it, try to keep your UV islands straight. For instance, if you have a rectangular island, it shouldn't be oriented diagonally. This will help mitigate lighting issues along seams.
I would also recommend creating a cage for your low poly. The cage determines the ray distance. Use a Push modifier to create a cage based on your low poly, and make sure it completely encapsulates your high poly, but don't push much further than necessary or it can cause baking problems.
Just a personal preference though, but give baking a try in Maya it just has less hassle to it.
Ahh thank you! Im getting much cleaner results after separating the hard edge pieces into unique smoothing groups and UV islands. So after this you recommend making my own cage as well? Can I duplicate my low poly in max, then push modifier so it just contains all of the high poly, and then export that and use it in xNormal as the cage?
So the options are to push out a cage from my low poly in max and import into appropriate field in xNormal or create one in xNormal itself? How do I make one in xNormal?
Sorry I don't quite follow, I create the cage in xNormal in the 3d viewer? I keep getting crashes in the viewer because my high poly (straight from zbrush) is too high poly!
Yeah, you can create a cage in the XN 3d viewer, the tools to do this are fairly primitive, but for simple meshes its quick to do. Try decimating the mesh, or swapping it for a lower sub-d level export if its crashing (and swap back before you bake)