View Full Version : Mirroring UV's

07 July 2010, 05:20 PM
Hey everyone, i have a quick question about this topic which has probably be asked to DEATH, but i am working on my current project and now I am entering the dilemma of mirroring my UV's to make the model more detailed.

On my older models, i have never mirrored any uv's on the model (for possible asymmetrical detail like physical wear and tear and bruises on characters), so I am just asking from some of the pros, yay or nay on UV Mirroring, especially if it is something like a piece of armour for a next gen model. I was going to do something like using a 4k texture for the armour but that is foolhardy and unnecessary (some parts of the armour have muddy normal maps :( ) And it may break the realism if i mirror my UV's but this is a game character and i will have no choice.

Thoughts? Thank you...

07 July 2010, 11:27 AM
as far as mirroring UVs goes, you already described the pros and cons.
You can save a lot (nearly half the UVspace) by mirroring it but then you will of course loose asymetrical detail.
I think you should base your choice on several factors:
-How close to the camera will the object be (if its the main character of a game, I would not mirror the UVs, but for a background object that is never close to the camera you propably wont be able to tell anyways)
-What is the overal resolution of the game (if it is going to end up on a nintendoDS screen you might get away wth mirroring, if its a 1080i HD game for PS3 or alike you propably wont.
-is it possible to see both sides at once?
I once modeled and textured a chameleon and since it is nearly impossible (especially with the shot i wanted to get) to see both sides at the same time i could mirror most of it.
it is also possible to use different UV sets or procedural bumps/normal maps to overlay with the color map. it is interesteing how much detail you can get out of two simple textures overlaying each other, creating interference patterns.

so as you see, its not a yes / no thing (for me at least)
maybe if you show some images and give some more specifics we can think about a more definite answere for the individual model.

good luck

07 July 2010, 03:46 PM
Be aware that UV mirroring is a big no-no when dealing with normal maps

07 July 2010, 08:13 PM
Be aware that UV mirroring is a big no-no when dealing with normal maps

Not true. Maybe in 1998 when no one knew how to program them properly into their engines. You can mirror anything just fine. Now, depending on your shader you can get poor results, but that jsut means your technical understanding is limited.

The downside is diminishing returns of reuse. The face is usually the best example of what should not be mirrored because of this. Nevertheless, you can use decals on the face for scars and other asymmetrical detail. On the body, however, mirroring can easily be hidden by outfit design.

07 July 2010, 12:21 PM
Be aware that UV mirroring is a big no-no when dealing with normal maps
I'd second that. Lots and lots of engines still use lighting models that count the normal information as being in world space, which would lead to the normal mapped details being inverted on the mirrored uvs.

07 July 2010, 12:59 PM
Hey everyone, and especially GradiusCancer, :beer:for the great information...I ended up just using a bigger texture on my model (4kx4k :sad: ) since I wanted some battle damage on the armour while keeping it asymmetrical... the engine I hope to use for future projects will allow for mirrored normal maps. Then again, i can probably scale everything with minimal loss of detail...

Thanks again... and btw, here is the project (was supposed to be quick) that i am working on

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07 July 2010, 12:59 PM
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