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I need some help troubleshooting some baking anomalies I have with my model. The following picture shows a window I have made with Blender 2.64 r51232 with a full render bake applied to it:


FrenchWindowFullScreen_1024.png


To create the full render bake I first baked color, normal and AO maps.


Here you can see some anomalies in the color map bake, the parts I have circled are not baked properly:


FrenchWindowDiffuseMap_1024.png

 

You can also see the problem in the following two images showing the full render bake. The glass pane is hidden as it is not part of the material used for the frame:

FrenchWindowWithUVMap_1024.png

 

FrenchWindowWithUVMap2_1024.png

 

I have tried rebaking the maps several times without any improvement. I thought perhaps the baking process had problems baking thin faces but the following image shows that some of them get partially baked:

FrenchWindowWithUVMap3_1024.png

 

I have created the UV map by using the SMart UV Project with angle limit set to 10.00 so to have as few islands as possible and an island margin of 1.00.

Does anyone have any suggestion?

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I'm guessing here -- What that looks like to me is that your AO map is too strong... Trying dialing down it's effect in your final texture bake (I use multiply and vary it's strength depending...)

Note, I'm assuming that you saved the lengthy AO bake to an image for later use in your texture stack :)

 

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Indigo Mertel wrote:

I thought perhaps the baking process had problems baking thin faces but the following image shows that some of them get partially baked:

Thin UV faces are indeed a problem if they are less than a pixel wide and not properly aligned horizontally/vertically. Here's an extreme example:

Screenshot from 2012-10-29 23:50:37.png

Usually the bake margin hides the pixel stairs at the edges, but if the faces are too thin so that the corresponding triangles cover less than half a pixel, no pixels get baked at all, and then the aliasing artifacts become fully visible in the form of gaps.

Smart UV Project is not ideal for models like these because it doesn't pay attention to alignment. You'll probably get better results with Lightmap Pack. This will produce more islands but align them perfectly. If the lightmap layout extends beyond the texture area, use Pack Islands to rearrange it.

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All those artifacts are results of texture alignment issues. There may also be some intersecting faces involved, but I can't say for sure without taking a look at the geometry.

Triangular UV islands are bad, especially if they are long and thin.  Rectangles are good, especially on pixel boundaries. You can never completely eliminate visible seams when there are color gradients involved, but you can do a lot to minimize them. The UV editor has options and functions to align UV edges with an underlying bitmap image. You can select vertices and snap them to pixels. You can align rows and columns of vertices.

Screenshot from 2012-10-30 21:11:17.png

You also need to consider the effects of "mipmapping": The graphics card maintains downsampled versions of all textures in memory (at 1/2, 1/4, 1/8 resolution etc.) and switches between them when appropriate. Downsampling also shrinks the bake margin, which is why seams can become visible when an object is further away from the camera. There is no reason to keep the bake margin at its default 2 pixels unless you bake in more than one pass. I always max it out at 64 pixels; it has no adverse effects on the result.

By the way, the triangle in the second picture can be eliminated by removing the edge at the bottom. You will get two quads on each side and save at least two vertices.

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The triangle on the normal map should be shrank down and manipulated in a way that it does not come down to such a long sharp point. . In some cases, you may have to Use the UV test grid to make adjustments to the UV map to where the checkers are not all stretched out and line up .  You will find that you will probably have to manipulate the UV maps most of the time. The initial unwrap is normally not always perfect (no matter what method of unwrapping you chose to use). Often times you will see stray verticies way out of place. you will have to grab them and move them where they belong and make sense...

On your normal UV map. grab that single vert on the end of the triangle in the UV map and push it to the right till is spreads out better. The point is too far stretched to where the edges are too close together. Looks like there not even a pixel to paint to/ Right below the arrow head on the UV normal map it looks like you have 4 edges over lapping

Don't be afraid to manipulate the verts on the UV maps and also think about using Multiple UV unwrap methods To help better break down your unwraps so they are not so condensed to one Map.

 

I like using the proportional editor to manipulate large groups of verts and normal for singles

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>> There is no reason to keep the bake margin at its default 2 pixels unless you bake in more than one pass. I always max it out at 64 pixels; it has no adverse effects on the result. <<

Really? I thought that spilling from one UV island to another was to be avoided at all cost. Do you do this when you bake all maps (AO, color, normal)?

 

>> By the way, the triangle in the second picture can be eliminated by removing the edge at the bottom. You will get two quads on each side and save at least two vertices. <<

LOL! You are good at challenging my scarce knowledge on 3d modeling... :) Do you mean like this?

OverlappingEdge.png

 

My understanding was that overlapping edges was another of those things to avoid.


EDIT: In the meantime I have reworked the topology for the side to improve the model and get rid of those triangles...

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unwraping and texturing is an artform in it self. First we learn the modeling then it becomes a big quest to tackle unwrapping and texturing. Hang in there. You will get it figured out. You will soon get to where you will be able to see the anomalies quicker and be able to manipulate them faster. It just takes a bit of practice and knowledge.

I am not sure if this happens with all UV Map programs or just a blender PITA

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Indigo Mertel wrote:

Really? I thought that spilling from one UV island to another was to be avoided at all cost. Do you do this when you bake all maps (AO, color, normal)?

Yes, I do that all the time. You will never see a bake margin spill into another UV island, because the process is adaptive, and the specified value is merely an upper limit.


LOL! You are good at challenging my scarce knowledge on 3d modeling...
:)
Do you mean like this?

No, I mean the vertex at the bottom between the front and back corners. The bottom is flat; there's no need for that vertex in the middle.

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Well, good news finally. I have managed to resolve all the baking anomalies. This is the final result:

 

Final.png

 

For the record, for the UV unwrap I have used Lightmap Pack. I have resolved all the anomalies by modifying the topology in the critical points, mostly by merging tris into quads and connecting some intersections with faces rather than stacking them.


Next step will be to bake the handle and possibly a single texture for both the frame and handle.

Thank you Masami and Dilbert for all your help.

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