Solved! How can I change my UV map to 8k from 4k without having to unwrap again?

michaelws · January 22, 2024, 6:16pm

I have a ton of hours of hand-painting hairs on my dog model. I stopped this project about a year ago and just recently started on it again.

I know I painted a lot of the hair in 3D Caot last year but now I found nothing but problems trying to get my UDIMs back into Blender from 3D Coat. I had the same problem last year and it took days of asking questions on the 3D Coat forum and perusing YouTube videos to get it to work. In truth, I don’t want to have to do that again.

I was painting with a 2-pixel brush in 3D Coat and it worked but in Blender, at 4k, the brushwork pixelates badly.

So I want to try to up the UV Map resolution to 8k. I know I can take the Image map into Affinity Photo and or Topaz and increase the resolution.

I’m not sure how to change my UVs in Blender. Can this be done? If it is possible can someone give me a little hand-holding in how to do it?

Thanks

cgPixel · January 22, 2024, 6:21pm

UV’s coordinates are from 0 to 1 for each tile and are independent from the texture resolution. if you change the resolution of your textures the same UV layout will be mapped on it

so what you need is just change the resolution of your texture to 8K and start painting on it. spoiler alert : it will so slow to paint on 8k in blender

michaelws · January 22, 2024, 6:24pm

Thanks…even at 4k it is slow. So I just have to up the resolution of the UV image? Even though the unwrapping was done at 4k?

cgPixel · January 22, 2024, 6:28pm

which means the texture plugged to the material of the object you’re painting on. your UV’s are not 4k or 8k. that’s the IMAGE MAP.

UV’s are from [0-1] if you plug a 4k picture 1 will be 4096, if you plug an 8k image 1 will be 8192

so yes just increase the res of the texture you’re using and the same uv layout will look the same on the new texture size.

michaelws · January 22, 2024, 6:32pm

Thanks cgPixel. Really appreciate the immediate reply. My fingers are crossed. If it doesn’t work then I will paint the pixelated 4k and smooth the art out in Affinity Photo or Rebelle 7.

cgPixel · January 22, 2024, 6:37pm

yeah just scale your texture outside blender. if blender is still open in the (image editor/UV editor) go to image=>reload
blender will update the new image (with the new size )and your UV’s will seamlessly look the same on it
there is no “UV image” : we have a “UV Layout/map” a set of 2d coordinates for your vertices and those get mapped on any "texture IMAGE "

good luck with how slow blender texture painting is on highres. but a small trick if you are painting on the 3d mesh. close the UV editor/image editor will speed it up a bit. cause blender will not have to worry about updating both

michaelws · January 22, 2024, 6:46pm

Thanks again cgPixel. Just a thought here. Do I need to stay in binary increments? I know 8k is 4 times larger than 4k. Can I put in an image that is in between 6k and 8k? Just while I am painting. Then I can resize it back down to 4k in a paint program that might give a better result.

Just a thought.

cgPixel · January 22, 2024, 6:54pm

yes you can.
you can even change to any size. or even have a different aspect ratio and this will not affect your uvlayout

but it is recommended to keep textures at those power of 2 squares for performance even texture painting doc recommend that

example below not doing anything but selecting a different texture map in the shader-editor and uv layout will follow the image size:

michaelws · January 22, 2024, 6:56pm

Thanks cgPixel!!! It’s actually working faster at 8k…but I took your advice and closed all the other windows.

michaelws · January 22, 2024, 7:04pm

You have made this 75-year old very happy! Thanks cgPixel.