troubles with normal maps

Sarford

Hi guys,

I'm having trouble getting good results with making normal maps. There are errors at corners of 90 degrees and more. I watched several tutorials but I can't get the result I want. Originally I was baking the normals for a side table when I ran into these problems and I couldn't solve them so I started with just a simple cube and try there but I get the same edge errors.

Tutotrials tell me that it's because of the color blending beween the two faces of the edge in the normal map and that seperating the faces in the UV's (and give them some padding) should solve the problem. For me however it didn't, as you can see. I even added extra edges in the lowres cube so that the normals wouldn't be averaged across the faces to help give a better result, but that didn't do anything either.

I'm using Modo for baking, but even when I bake in substance designer I get there errors although way less. What is the way forward?

Obscura

Wait, why do you want a baked normal map from the edge smoothing, when you already have support loops? All you need to do is to set the mesh to fully smooth shading and you get the smooth edges...

Sarford

True but I added the support loops to try and get rid of the errors, I get the same results without the support loops. On the original model, the side table, I want to avoid adding support loops (on the legs and frame) as it will almost triple the vertex count.

NoRank

You're baking it without a cage, right? If you are, check the average normals box on substance baker and it should be fine. 

Sarford

Cheers NoRank, but the (last) image is from a bake with normals averaged (I am indeed baking it without a cage). Not being a game artist (I work in VFX) I can't really validate the result though, maybe the substance bake is correct and this is the best a normal map can do (the error is minimal here)?

Sunray

You should put a seam on every hard edge of the cube and have your normals of your cage averaged if you don't want to put a seam somewhere but want to get your smoothing correct. Bevel the edge you can just add one segment to try to keep the polycount as low as possible.

NoRank

Sarford said:

Cheers NoRank, but the (last) image is from a bake with normals averaged (I am indeed baking it without a cage). Not being a game artist (I work in VFX) I can't really validate the result though, maybe the substance bake is correct and this is the best a normal map can do (the error is minimal here)?

Well yeah, there is a limit for how round the corner will be with a normal map.  You kinda have to experiment with that to get the result you want, sometimes you really have to put some more geometry on your lp to make it round.

Sarford

Ok, I finally worked it out. The problem was that I had the smoothing of the low res mesh set to 0 degrees. Apparently because of that the angle was too big for the normal map to handle. I had two versions of my side table, the original one and one with the sharp edges beveled. With the original one having a smoothing angle of 180 degrees, and the beveled edges version a smoothing angle of 60 degrees I was able to get a perfect bake.

Of course a smoothing angle of 180 degrees gives gradients in your normal map to counter the mesh smoothing and is not advisable but it still works. I decided to continue with the beveled edges version though because the shading is better on that version and the increase in vertex count was not as big as I expected, 528 instead of 296.

Thank you all for helping me on this problem!!

side table with sharp edges and 180 degrees smoothing


normal bake with 180 degrees smoothing


side table with beveled edges and 60 degrees smoothing


normal bake with 60 degrees smoothing