UDK model darkens with smoothing group

Purge117

Hey,
So having some trouble with UDK. Not really used it much but I am having a problem with smoothing groups. If I import an FBX with smoothing groups, the result seems to have odd shading. It is very dark at the higher points.




Has anyone seen this before?

Also worth noting that this happens with no maps applied also.

Thanks in advance!

Shrike

its because you split your smoothing groups not properly. It looks like you use one smoothing griup for most of the model, and so your shading wants to make it look like round, like a ball, while your geometry is not shaped like that at all, giving you these dark and strange shaded areas.



on the left is one smoothing group , which is usually not wanted , second is what you want

you can use your smoothing groups like on the colored one, or just take a different smoothing group for every surface you want to split, that dosnt matter

if you are using max, you can select your whole mesh and type 45 or 50 on the smoothing group window and apply that, that
will make smoothing groups based on angle (I found these numbers working on mostly everything) and that often does most of the work for you if not all.

if you are using maya or cinema or anything you want to break groups on the edges like on the right image


If you bake from a highpoly that has the shape and smoothing you want, your lowpoly smoothing will try to accept that shading, so you can work with not splitting everything, even if it looks wrong on your lowpoly (splitting requires more memory), the normal map will bend it back to the form of the highpoly, but there are limits.

Keep in mind that your UV needs to be cut where your smoothing splits are, else you get artifacts

Purge117

Hi Shrike
thanks gor the reply. I have not tested this yet but it is the smoothing groups as that is what basically broke it in the first place. I may have misunderstood a tutorial I saw which said that for normal maps to work, the whole model must have a single smoothing group I take it that this isn't the case.

Obscura

Well. Theoretically that would be the best, but in the real life there are many cases when this doesn't work well. There are workarounds for this, but often the case select the solution, but there are general solutions too. Everything has its positive and negative side, but it worth to check out these, because its not rocket science, and a good artist should know about the possible solutions.

- First you should do some search about this topic, to understand how it works, and why. Then try out some different solutions.

You can probaby keep the one smoothing group though, you just need the xnormal workflow, or more geo, or handplane.