Author Topic: UV mapping nightmares and frustrations  (Read 4439 times)

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UV mapping nightmares and frustrations
Hi fellas,
So I have been TRYING to do a proper UV map for one of my models. However, it's been a frustrating experience so far and after reading up, I see it's one aspect most dread when doing 3D modeling. I am currently learning how to in the Wings3D software and yes I have investigated others before this and well, I have to start someplace right?  Truthfully, I felt this would be a good start even if it turns out not to be an optimal UV map, but practice makes perfect right?  :D

Anyhow, it got me thinking of WHY is it so difficult and a major pain to most, if not all modelers to UV map a given 3d model? has anyone, any company actually made or are creating a seamless, easy to use, yet turn out a UV map that would impress seasoned texture artist/graphic artist out there (like me).

For those who have done UV mapping, what is your experience? Do you actually like UV mapping? Do you create models that are geared to making UV mapping easier and leave out some details or detailing because it would be a nightmare to UV map?

Thanks in advance for your comments! I really want to know your experiences!

P.S. I hope this is the correct forum for this and if not, Admins, please move to proper location! :D
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Offline Oddgrim

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Re: UV mapping nightmares and frustrations
Uv mapping is not fun, even after all this time doing it. Its easily my least favorite part of model creation. And to my knowledge theres no program that can make a seamless ready to use texture, even in maya which has pretty good uvmapping tools you still need to tweak and adjust the seams. 
So, my attitude to the whole process is : deal with it.
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Re: UV mapping nightmares and frustrations
UV mapping is the toughest part of the entire creation process indeed. So far I managed to successfully unwrap one model (the Sabre. I don't count missiles and other small stuff) and now I see how badly it sucks.

A way to deal with it? Well, I think the most important part is to constantly pay attention to the modeling process. Having an idea for a cool looking detail? Then automatically try to imagine how would you unwrap it later. I learned that I must avoid certain shapes so far because I have no idea how to unwrap them properly without stretching the UV islands like mad. For example. On the picture below. Blender has a nice function called smart UV project. It can unwrap the top part of the beveled chunks very nicely but the problems begin with the lower rectangular stripe. Normally, if I would have been designing such a part for one of my paper models I would have simply made it a separate part. But on the other hand, making it a separate isle on the UV will make the digital painting even more painful.


I think this thread might be a good place to share our concerns/tips/whatever, regarding the UV mapping.


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Offline Droid803

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Re: UV mapping nightmares and frustrations
For those who have done UV mapping, what is your experience? Do you actually like UV mapping? Do you create models that are geared to making UV mapping easier and leave out some details or detailing because it would be a nightmare to UV map?

I detest UVmapping. I'm also no good at it. It's tedious and not very rewarding. It's not *hard* to do (at least, to the poor levels of quality that I can achieve), and I don't presume it gets any *harder* to do even on complex shapes (would just require more than just using planar projections for everything, which is what I do because 1) I am crap, and 2) I am too lazy to learn other unwrapping methods), but would just require usage of other methods and just tweaking those.

The only part that's remotely entertaining about the whole process is fitting all the islands together onto a square. Everything else sucks.

I do create models geared towards making UVmapping easier (more symmetry=less surface area to actually UVmap).
I avoid all such details that are a "nightmare" to UVmap I wouldn't even know how to map it properly, and it'd look horrible anyway, so might as well save the effort.

My attitude towards the whole process is to not deal with it if at all possible, and if I must deal with it eventually, prepare for that eventuality by taking all steps possible to minimize the amount of work that needs to be done at all costs.

I mean, between an asset that is crummy and half-assed/half-baked because I'm trying to avoid uv-mapping as much as possible, and an asset that simply just never gets completed because of getting stuck at uv-mapping, I would take the former over the latter any day of the week. It won't win any contests but at least its something that I can shove in game and build missions around. The latter is plain and simply worthless.

My position is very much shaped by the experience of wishing to bring a number of custom assets to complete a WiP mod which was already well on its way, and is probably a poor position to take if one wished to become competent at the art. I only learned what I did out of the sheer necessity of a few custom assets.
« Last Edit: September 09, 2016, 05:53:57 pm by Droid803 »
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Offline zookeeper

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Re: UV mapping nightmares and frustrations
I think I actually enjoy UV mapping. However, the problem is that with complex models it just becomes overwhelming due to the amount of elements you have to handle (depending on the model of course; it's not bad unless there's a lot of greebling). Also it's arguably not very fun to have to try to take things like mipmap bleeding into account.

 
Re: UV mapping nightmares and frustrations
Firstly, I want to thank you all for taking time out and posting responses here. Your comments are truly an eye opener and I value your ups and downs in all this. I'll admit because of my 35 years of both as a Hobby and profession, I am a detail freak. My art works reflect this and I would have hoped to do the same for 3D modeling.
It's amazing how much we can create in a model, yet cannot give that detailing love a proper UV map without blowing up half your brain cells. :)
 
With all the time, effort to make modeling a joy, I would hope the same would be given to a UV mapping program that does everything we expect it to do and not be such a major pain to do. I also bet if any programmers out there can see this plight, create a proper UV mapper that does what we need, you would think they would be almost printing money on this.

Please by all means keep the comments going! maybe we can get somewhere in all this?
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Offline DahBlount

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Re: UV mapping nightmares and frustrations
UV Mapping becomes significantly easier when you use view projection while viewing a surface from its normal. Doing this for individual surfaces and then stitching them together works incredibly well for all intents and purpose and I've gotten some pretty good results from it thus far.
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Offline Black Wolf

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Re: UV mapping nightmares and frustrations
The problem with automatically UV mapping is that it either is, or is close to, a hard AI problem. Doing UV Mapping well requires elements of creativity and understanding of the ultimate aim of the process. The computer is capable of unintelligently folding out polies, but that doesn't help you, the person who has to deal with it, create a decent looking model, because the UV will be geometrically perfect, but entirely non-optimised. How doea the computer know which polies need to be connected seamlessly, and which need to be off in their own island for the purpose of creating hard edges? How does it know which pieces can be overlapped, and which need to be unique? Boring though it may be, UV mapping requires thought and creativity that a program can't sensibly provide.

There are, however, some things that can make the process less awful. The key, in my opinion, is to stop treating modelling, UV Mapping and texturing as three different processes. Definitely don't farm any of these steps out unless absolutely necessary. Each part, to a greater or lesser extent, is made easier if it can be done in concert with the other two.

For example, when I model a ship or station, I'll often make the greebles separate subobjects for the purposes of making the destroyable. One other advantage is that you can take that submodel, align it so that the majority of the detail is on the X, Y or Z planes, then export it for UVing separately to the other parts of the ship. UVing is immensely easier when you're on nice neat angles like that. This same mechanism is also useful if you want a lot of repeated detail - make it once, UV it, then duplicate the UVed model.

Droid also pointed out the value of modelling to UV. Symmetry is one good way to do this, but there are lots of tricks around clean geometry, regular angles (doesn't have to be 90 or 45, but just something you can remember for future use) and other things.

One specific trick I use is to make shapes in as simple to UV a format as possible. For example, when I want a run station, I build the ring as a tube (with all the elevation changes, ditches and ridges etc.), then UV the tube, then bend it 360 degrees into a circle. Immensely easier to UV map and much cleaner/less distorted to boot.

The connection goes the other way too. While you're UV mapping, you're often likely to spot errors you didn't notice during texturing (zero width faces are common). Being able to go back and fix these is very valuable. You may also run across geometry that's particularly tricky to UV. If so, you have the option to go back and rebuild it in a friendlier manner.

Finally (and this is a big one), UVing and texturing should go hand in glove. Yes, you need to have a UV map before you start texturing. But that's a long way from the end of UVing. You will, without fail, find aspects of your UV that are wrong while you're texturing. Some polies will be too small, others warped, some will be overlapping, or a seam will be in a bad place - there are hundreds of little changes that you should be making during the texturing process, which is why it's (IMO) critical to be able to do both. I honestly think that it you can't UV, you can't texture.

A few specific tips:
Get a proper UV program. This may be specific to Max, but I find that while the inbuilt tools are fine for basic stuff, they won't be good enough for complex meshes, and they certainly aren't as efficient as a dedicated piece of software. I sprang for Ultimate Unwrap since I'd spent years with Lithunwrap, and it was money very well spent. There are likely other good ones out there too.

Don't be afraid to move polies and verts around manually. When I have a circle modelled that I'm happy to be radially symmetrical, I'll often break it into tris and manually line up the outer edges. This let's me draw straight lines on the map, as opposed to circles, which never look as clean.

Use checker maps. These let you make sure, at a glance, that all of your faces have roughly the same mapping density, and that your vertex manipulation hasn't warped any polies.

Use auto smoothing to separate complex bits of geometry, then select by smoothgroup to break them up for UVing. This can give sharp breaks with clean lines in amongst complex bits of geometry, where selecting individual polies might be very difficult or tedious. The grow and shrink selection tools are also useful here.

UV greebles completely and separately before attempting to combine them. This might make for a slightly less efficient map, but it will keep relevant polies geometrically close to one another, as they will have been already arranged efficiently and close to one another.
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Re: UV mapping nightmares and frustrations
Dablount, Black Wolf and others, you guys are GOLDEN for stepping up and posting your comments, views and experiences! Thank you ever so much and others who are reading up on this, PLEASE post your feelings, ideas and what not as I find all this fascinating and truly informative!
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Re: UV mapping nightmares and frustrations
Organic UV mapping (people, creatures...etc) is a nightmare!  Man-made (or alien) is much easier, break the thing into UV pieces and work from there.

Max has two very useful features I've found (there's probably a Blender or other equivalent):

Stitch - This lets you easily connect one piece to another (just select the edges or vertices of piece A and it'll snap piece B into place)

Relax - HUGE timesaver.  This will get rid of most distortions in the selection.  Stitching will often produce warped results and relaxing fixes those.

Also be glad your just working with one UV channel... things get really confusing when there's 2 or more  :eek2:

---------------------------
Edit: Here's a tutorial I wrote nearly ten years ago... [I'm losing track of time badly  :( ]  Some of the things are wrong or just avoided but the jist is still there.
http://www.hard-light.net/forums/index.php/topic,47240.0.html
« Last Edit: September 11, 2016, 04:34:44 am by Scooby_Doo »
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Offline zookeeper

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Re: UV mapping nightmares and frustrations
Relax - HUGE timesaver.  This will get rid of most distortions in the selection.  Stitching will often produce warped results and relaxing fixes those.

Yeah, relax is the thing. My usual UV workflow is to select and detach an element, deciding how I want it to unwrap, applying a naive planar map or something to get something to work with, and then welding/unwelding the vertices I need in order for the whole thing to smoothly fold open in the manner I intended when I hit the relax button. Of course it usually takes a few iterations and trying different relax modes to achieve that for complex shapes.

 
Re: UV mapping nightmares and frustrations
So in reviewing all the above comments, I think the following sums up what most look for in a UV mapper:

un wrapping and having the edges stitched with ZERO distortions.

ease of placing islands to maximize space, Auto arraigning with several selectable options  to choose from such as manual placement of each island from a graphic list. etc.

simple, easy to understand step-by-step instructions for UV Mapping with alternate ways to UV map different surfaces for a proper UV map.

These I see from my very limited experience and please by all means, add or revise this if you wish too for a list of desired features for an optimal UV mapper.

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Re: UV mapping nightmares and frustrations
You also want need to decide what parts of the map to stitch and what parts can be left unjoin.  Generally you want everything to be connected so it looks like one flowing piece, but that's not possible.  So your best bet is to place the seams where it's either not really visible (in the nokes and cranies) or where it's suppose to be obvious (like when there's a texture change, you might as well take advantage of that)
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Offline zookeeper

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Re: UV mapping nightmares and frustrations
Generally you want everything to be connected so it looks like one flowing piece, but that's not possible.

I think even that depends. I used to try to make things as connected as possible, but I found out that at least in the models I unwrapped that resulted in texturing difficulties. Especially with objects that physically wouldn't be one solid piece sculptured out of something, I find that you often want those seams at material boundaries, or any boundary which you want to be clearly defined. If the boundary only exists in the texturing, then it'll be a bit more soft and blurry and less sharp than if there was an actual UV border there (because of interpolation, and individual texels wrapping over a 90-degree angle in the model). Especially if the boundary isn't a strictly vertical or horizontal line, but a diagonal or curved line, because then you get jaggies.

So, all that comes back to UVing and texturing going hand in hand. If you UV the model without knowing how you want to texture it, you'll probably find out in the texturing phase that some bits are hard to do the way you want because the UVs don't facilitate it.

Also what I've found myself doing countless of times is drawing, say, a line across a ship's hull which goes through several UV islands. Naturally, when I do that the texels aren't perfectly aligned with each other. So at that point I just slightly shift the UVs until I get a clean perfectly connected line. The shift is so small that it doesn't really result in needing to change anything else, but it really helps in getting some low-res details perfect. Of course, whether perfectionist twiddling like that makes sense depends on the texture resolution and from how close the model might be viewed.

 
Re: UV mapping nightmares and frustrations
That pretty much explained in detail my last sentence :-)

btw... seperated pieces of map are usually referred to as "uv islands"
Also... if you're going to uniquely paint each piece of the map, you must remain in the [0..1] range of the UV.  Otherwise if you're going to tile, [0..1] isn't important (unless there's a shader that requires it)
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