UV Mapping and texture size

[Madeliefste Oh]

For texturing I like to work on a big canvas, because you can always shrink back in size without loosing quality. Now I made a UV Map on a 2048 x 2048 canvas. When I upload the image to SL as a 1024 x 1024 texture the texture fits perfect on the mesh (the fan in the back). But now when I shrink to size back to 512 x 512 the UV map doesn't fit the mesh anymore (the fan in the front), but it includes the outline of the UVmap.

 

Is this a bug? Or what is happening here?

[York Jessop]

Is it possible that as the resolution is lowered the UV outlines become wider to fit into the lower number of pixels?

[Gaia Clary]

Usually you will not have UV-outlines on your final texture. To avoid this sort of problem you can typically specify a margin, which ensures that the colors of your texture at the map borders will be propagated a bit into the not used parts of your UV-texture.

In Blender look at the Render properties -> Bake

Right under the Bake button you find the Margin settings. I have it set to 6 (pixels)

[Maeve Balfour]

When UV texturing, I find it is good practice to slightly overfill beyond outline borders of each piece, to avoid this specific problem. When the texture maps are resized, often the anti-aliasing effect will cause the fringeing effect seen in your examples here (the slight mixing of colours in the "smoothing" involved in reducing an image size).

By texturing a few pixels outside the dimensions of each piece in the UV layout, this tends to remove the problem.

I am fairly sure this is the case happening here - I hope this helps for you :matte-motes-smile:

[TANAKAAKIO Inshan]

Because of fudge factor of size conversion, unpainted area of textures is shown.
These show up as black lines.
Sometimes, Lower LOD causes black lines also.
Painting surrounding areas of island widely prevents from this problem.
I think there is more to learn in UV-mapping.



[Madeliefste Oh]

Thanks all for your replies. I understand it now.

[Rage Riptide]

Thanks. That's just another button that I didn't know what it does. Another one down, several hundred to go.

[Esprite Xavier]

So this is a common issue with games using mip maps. 

My personal recommendation when trying to solve combat this is to install the photoshop filters that come with a popular texture baking application called xNormal. http://www.xnormal.net/

When you do the installation you don't actually need to install xNormal itself (I use it alot though ) and can just install the photoshop filters.  The filter "Dilation" basically takes the pixels on the edges of your UV islands, stretches, and blurs them off the sides by however many pixels you set it to. Provided your textures are their own layer and seperated from the background. This should combat the wierd edge seam issues.

[Ashasekayi Ra]

A Photoshop filter comes with Xnormal? 

[Esprite Xavier]

Yep! Not only Dilation there are some nice ones for generating and editing normals. 

[Ashasekayi Ra]

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Esprite Xavier wrote:

Yep! Not only Dilation there are some nice ones for generating and editing normals. 

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Oi

I really need to do some searching. Somehow, I never noticed them in there.

Edit: I just found it. Woot! Thanks for pointing that out.