Two UDIMs without UV seam.

ouma

みなさん、こんにちは。初めての投稿なので間違いがあったらごめんなさい。

また、英語は私の得意分野ではないことをご理解ください。

さて、バイクのモデリングは完了したので、テクスチャリングを始めます。タイヤの UV をどうするか考えていたところ、他のアーティストを参考にするために ArtStation を見ていたら、彼の ArtStation を見つけました。( https://www.artstation.com/marketplace/p/nkxm1/toyo-proxes-tq-dot-drag-radial-tires-345-40-r17-106y-ll-real-world-details?utm_source=artstation&utm_medium=referral&utm_campaign=artwork_search&utm_term=marketplace  )

1) このタイヤモデルには UDIM が 2 つありますが、継ぎ目がないようです。このように UDIM を使用しても問題ありませんか?

2) 問題ないのであれば、このように使用する場合に注意すべき点はありますか？

3) 自分で試してみたところ、タイルの間にアーティファクトが見られました。原因は何でしょうか?

Benjammin

I'm guessing that your example isn't UDIM at all, just a tiling texture. 

Thanez

I've never heard of using UDIMS this way, to have one continuous strip of polygons to go from 1001 to 1002. WEIRD!
It looks like texture filtering issues. Trying to wrap my head around this, I'm wondering if you could break texture filtering in a setup like this if you clamped the texture, so texture filtering would be unable to sample the previous/next UDIM? If that were the case, you would see the same issue twice around the circumference of the tire.
Try wrapping the textures? Is that even possible? You're about to find out, I guess.

Why even do this though, I'm confused. I'd just UV the tire from exactly 0 to 1 in UV space, and wrap the texture. When Anistropic or other filtering gets to the pixel at 1 and looks to the right, it finds the pixel at 0, and can filter between them.

Eric Chadwick

You may want to try different wrap modes in the shader: repeat (traditional texture tiling), clamp (edge pixels are stretched out beyond UV 0-1 space), or mirror. More info and a pic: http://wiki.polycount.com/wiki/Texture_Coordinates#UV_Address_Modes

poopipe

UDIMs require padding because of what Thanez says above.

If unique painted /baked detail is required and you want to use UDIMs, you need to change the UVs.