Question about UV orientation
polycounter lvl 5
Hi
Just a quick question - is it generally okay to have UV shells at an angle? I believe I was taught that they should always be vertical or horizontal, but in this case, where the shell is a weird shape, and the UV checker shows the map as being the right way up, it's at a bit of an angle.
Thanks
Replies
You'll get stepping artifacting along your edges as its not aligned to the grid, which becomes much more apparent the lower the resolution. However, given the organic nature - your uv shells aren't completely straight to begin with, so those issues would pop up regardless of its rotational orientation.
See, I'm confused about that - them not being straight. I had some feedback from someone else who said same thing, but that's how those shapes come out once I add the cuts and use Unfold and Optimise. :-\ Do you mean that the outer shell needs to be straight/rectangular? That I should use Straighten UVs? I've noticed whenever I've done things like that, the Distortion checker goes red or blue as they're stretched out of shape.
How would the stepping artefacting work exactly? I thought that kind of thing happens if they're either not in the 0-1 grid, there's texture bleeding, or a texture in Photoshop isn't quite filling the UV shell?
Thanks
Check out this page from the substance documentation: Aliasing on UV Seams. Straightened UVs (plus potentially less empty space) for slight UV distortion is a good trade imo. If the bakes turn out fine, all good.
Okay, that makes a bit more sense. I'll see what I can do. I would prefer having completely neat and straight UVs to fill in the space, but I imagine rounder UVs are going to be pain to straighten without making them look a mess.
I mean not everything needs to be straightened, just where it makes sense, tube-like parts are easy case for example. Essential part of the equation is also how seams are set.
When unwrapping organic topology, I sometimes straighten the borders, then relax the contained UVs.
I would prioritise making progress in the project. Sometimes it's good to sprint ahead, check how textures come out at target resolution, if they don't, improve. Best learn with each project as problems come up, else too much to swallow.
Thanks. To be fair, the character I'm working on is very simplistic and they only use base colours. :)
The amount of adjustments I need to do for this project isn't much, but it's good to learn and get into the habit of straightening UVs; it's not something I've done very often. Only with things like tubes. For those, I tend to use the Unitize function.
I also stumbled across this Maya tutorial from another thread on here regarding the same topic:
Is it considered fine if you just keep the interior edges/faces uneven? I've straightened the borders, pinned them, and then just used the Unfold and Optimise for the interior to reduce the distortion.
EDIT: Okay, that doesn't always work too well. Some shells explode weirdly even if the sides are pinned. XD
that is fine but i feal like some of the outer UVs need some balancing this will likely stretch a lot in some areas.
what i usually do is relax it a bit, straighten and relax again, then straighten until i have something that looks balanced
The outer UVs...? You mean the edges at the sides inside the shell...?
I've gotta be honest, I can't say I'm a fan of the whole straightening process. I get the reasoning for it, but there's just something about having clean shells that show white instead of red or blue with the distortion checker that feels more natural to me. It must be an OCD thing. The straightened edges look tidy, and allow shells to fit better in the UV grid, but it's the distortion and stretching that bugs me. 😅 I also suspect that some of these shells, such as for the head, tail and nose etc. aren't going to look or work too well with being straightened.
The border vertices are spaced out very uneven, see upper corners left and right for example? I assume with your mesh the verticed are distributed evenly, so you might want to do same for their UVs.
It really depends on the texturing.
If the Sam & Max bunny character had sewing seams running down the sides of its arms and legs, like a stuffed animal, then you would want those UV seams to be straight.
This would allow the texture to use a straight line of pixels.
If the UV seams are rounded, then the texture would need antialiasing, which blurs the texture if it's low-resolution.
Not sure if I'm going about it right, but I've tried straightening some of the edges and then using the Optimise Tool, which only starts putting it back to how it was before, but I don't feel as though it's looking 'balanced'. I prefer having perfectly straight edges, but I also like having little to no distortion.
Um... I don't actually. 😅 The borders are looking very straight to me, but the interior edges are very wonky.
I've been back in 3DCoat and tried to get the vertices/edge loops as straight as possible. This particular pieces is for the torso.
The first time I did the UV unwrapping, it was a very rushed job. The torso came out pretty much the same as it's been done this time. The aim is to fill up the space better and fix up some other minor issues. As I'm using Substance Painter and UE4, I don't recall seeing any seams or aliasing the first time. Again though, they're very basic colours and there's few of them. :)
Hmm. I'm feeling very conflicted about this approach of straightening UVs. :-\ I felt fairly confident with UV unwrapping until now. Here's a part of the character showing how the UV was looking before and then afterwards by straightening everything:
Obviously, the bottom one looks much cleaner, though the upper one is more relaxed. The UV pattern looks fairly clean for the most part, but the same can't be said for the left side...
The lower resolution the geometry, the more apparent the distortion will appear on straightened geometry. Remember, it's only ideal when patterns/graphics/special details are needed as mentioned, straightened UV's are best here.
Hi! Maybe I didn't word it right: Yes, border edges are looking straight, but the vertices on the edge are not distributed evenly.
Split the corners like so to avoid UVs stretching:
Hmm. I see. I did think that the geo itself was going to be a contributing factor. That last example I posted were of the teeth and the edges aren’t exactly straight for it. The whole silhouette is ‘wavy’.
Sooo… are you saying straightened UVs should primarily be used if patterns/details are needed in the texture…? But otherwise, they don’t have to be used if not…?
Again, this character has no details (apart from the belly button on the torso) and it’s all just flat base colours. All parts of the mesh are pretty much round. I don’t see straightened UVs being much use for things like the head, eyes, nose, tail etc.
Ohhh, I see what you mean. Yeah, I was playing around with that shell some more and was trying to get all the interior edges straight. Next time, I’ll try to get them more evenly distributed.
Also, thanks for the suggestion. I’ll give it a try and see the results next time. :)
Honestly, just experiment.
Relax everything and see if there is any artifacting along your uv seams after your bakes/textures.
As Fabi_G mentioned, make sure your UV vertices/edges are mimicking what the geometry is doing in order to keep distortion down as much as possible. If your geometry in 3d is evenly spaced, as should your UVs. If there's an area thats clustered in your geo, your uvs should as well etc.
Objectively, straightened uvs will provide no stepping/aliasing, and is extremely convienient when tiling patterns, graphics, whatever else at the cost of distortion - but if those aren't prevalent, you can relax everything and determine if there are any issues. I believ that's all we're getting at.
Okay, thanks for the advice. I'll experiment and try various things and upload the results - of the unwraps and the baked/textured results. :)
I couldn't manage it in the end. :( I tried experimenting, tweaking, straightening etc. but none of it was sitting right with me. And it was taking too long for something simple like this character. I decided to just stick to Unfold and Optimise, though I did straighten the odd edge here and there. Just wanted to focus on getting things more tightly packed than before. But I guess I will need to try and focus a bit more on straightening UVs for the next project, particularly a more real-time character.
I'll do a test bake and upload the results with all the textures applied. It'll most likely own be at 512 or 1K anyway.
Everything's come out bang on really in Substance. :)
Might have to rework the seam that separates the sole of the foot though. Maybe...?
The only stand-out area that looks iffy is around the base of the neck:
That'll probably look different in engine with padding and mipping working on the textures.
I'm not sure if mipping is enabled, or how to access it, but the area is still noticeable ...but only if you zoom right in and go looking for it. Otherwise, it's really not going to be seen.
do you even need a normal map for this ?