One method that might work would be to have strips of planar faces where you plan to split your UVs. Then split those strips down the middle and use that split as your UV border.
Doing that should minimize the variation in the normal map from one side of the UV split to the other.
Here's a bad example for mirroring in UDK but the same basic idea and principles apply:
With that said I usually don't make unique normal maps for tree trunks because they're just too large. I guess you use a tiling bark detail normal map blended with a unique trunk normal map in your shader, but then your shader gets more expensive, and since trees tend to get instanced all over the place performance suffers...
I guess this problem would still have to be solved for a unique "hero" tree.
Thanks Ben that helps. To be honest I have no clue how to setup that kind of shader that you're talking about but would definetively like to know. Tho I would propably need to reUV my Tree to prepare the bark for tiling as it bends alot and the uv's are layed out flat and relaxed.
I obviosly can't see what vision you have for this particular tree, but in general, this is a PRIME example of an instance where normal map seams just DO NOT MATTER. Anything organic that isn't a character tends to be pretty forgiving when it comes to seams like this, and there is a lot you can do to hide them.
If you look at some of the trees Epic has already provided you will note that there are lots of "little issues" with these organic assetes that you have to actually hunt for to notice. Once everything is lit and has materials on it people just don't care, and neither should you.
If this were a hard surface prop with a very specific value/lighting signature then you would have a completely different problem on your hands, and at that point you may want to investigate a technical solution to meet the aesthetic demands of your audience.
As always its up to you though, your going to learn more if you make a few mistakes and cranking out a large volume of trees than you will if you spend hours slaving over this one issue. So my advice is to consider the amount of effort you invest into fixing this in that context.
@ jacose : Ye i've realized I could cover it up with some vines and vegetation after rethinking. There was too much trouble to rebake and reUVW it again. I'm kinda forgetting sometimes that this kind of little issues can be fixed like that. Need to get rid off that precious polishing habbit I got. Thanks for the advices
@ EarthQuake : Just for the test sake I made a copy of both mesh and material and put it in UDK to see what will happen. On the copy I've added a Constant3vector with 1.-1,1 value to invert the green chanel. Left one is with Inverted Green channel. Right one is as it came out of the bake. Still the right one looks better.
Anyway time to move on with this asset. Thanks for the replies guys
Replies
One method that might work would be to have strips of planar faces where you plan to split your UVs. Then split those strips down the middle and use that split as your UV border.
Doing that should minimize the variation in the normal map from one side of the UV split to the other.
Here's a bad example for mirroring in UDK but the same basic idea and principles apply:
With that said I usually don't make unique normal maps for tree trunks because they're just too large. I guess you use a tiling bark detail normal map blended with a unique trunk normal map in your shader, but then your shader gets more expensive, and since trees tend to get instanced all over the place performance suffers...
I guess this problem would still have to be solved for a unique "hero" tree.
If you look at some of the trees Epic has already provided you will note that there are lots of "little issues" with these organic assetes that you have to actually hunt for to notice. Once everything is lit and has materials on it people just don't care, and neither should you.
If this were a hard surface prop with a very specific value/lighting signature then you would have a completely different problem on your hands, and at that point you may want to investigate a technical solution to meet the aesthetic demands of your audience.
As always its up to you though, your going to learn more if you make a few mistakes and cranking out a large volume of trees than you will if you spend hours slaving over this one issue. So my advice is to consider the amount of effort you invest into fixing this in that context.
Hope that helps, nice looking tree btw.
@ EarthQuake : Just for the test sake I made a copy of both mesh and material and put it in UDK to see what will happen. On the copy I've added a Constant3vector with 1.-1,1 value to invert the green chanel. Left one is with Inverted Green channel. Right one is as it came out of the bake. Still the right one looks better.
Anyway time to move on with this asset. Thanks for the replies guys