Splitting-up UV maps
Saiyaness
Posts: 715
Greetings,
Quick question. I have a finished critter model with multiple Shading Domains and Material Zones for the purposes of easier Polygon selection for grouping for rigging and weight mapping in Daz Studio.
However, I haven't started UV mapping it yet and am chewing a few nails (not that I need an excuse *gnaws*) over how I should tackle it.
As 90% of the model is one object, I don't want to squish it all onto one UV map. I would like to have separate parts for easier UV mapping for mixing and matching with colours and textures in Daz.
So how so I go about it? Do I...break off limbs/appendages, etc and make them a separate object? So they then get their own UV map?
Or can I keep it as one object and tell Hexagon that I want separate Uv maps for certain bits? :o
I'm happy to do the former if necessary...I just hope it keeps my Shading Domains/Material Zones. *shudders* I'm sick of selecting polygons.
Anywho! Thanks for any answers! >=D
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I once did a short tutorial with screenshots in the old forum but I lost the pics and can't find the old thread now so I'll do the best I can with words. I hope you can follow..
The first thing is to set up a separate shading domain for each are you want to map. You just select polys and on the right hand side in the "Shading Domains" tab, click New. Do this for every area you want to have its own map.
Now once that is done, you can UV map each shading domain. The trick is to turn off all the others by clicking the little icon of a filled sphere which toggles the domain to visible/invisible. With just one domain visible, UV Map it, the map will only apply to the shading domain that is visible. Just get the basic projection in place, don't scale or adjust it yet because when you make the next one it will rescale everything and you'll have to do it again. Get the basic UV projection in place for the first domain and then turn it off, turn on the next and repeat the process until they all have a basic map.
Now you'll need to clean it up. Each domain has a separate UV map but they are all overlapped if you look at them in UV view. If you want, you can now select each domain and adjust it to fit a portion of the map so they all fit cleanly without overlap on a single map. But you don't need to have them on a single map, if you prefer to have a full size map for each one by itself then just turn off all domains but one. Change view to UV view, you can now see the map for just the specific domain you want and adjust the map until it looks good to you. Then turn it off, turn on the next one, adjust it so it looks god, keep doing this. Once you've done it for all of them, they each have a separate map.
I hope that helps.
Quick question - will this method work with "real"unfolding - seams and pins - or only for projection mapping? Just thinking that I have never had any luck with it apart from using projection mapping, which probably won't work all that well with an organic model.
You know something, I never tried it before with seams and pins. But I just did. I created two spheres and connected them together via an undulating connecting tube. I mapped each sphere individually, that worked fine. Then I turned off both those domains and tried to map the twisted tube via seams and pins. It worked fine too but the sphere maps were ruined, even though they were off when I created the new map for the tube part. So I think it does not work with seams/pins unfortunately. That's a bummer.
Yeah - bummer. I was hoping you had found a method to make that work - would be so useful:)
Wow, thanks Grinch for the response! I see exactly what you mean so I'll try it and see if it works, even if your experiment in the later post didn't work with seams and pins. With my plethora or shading domains though, they may be small enough to not need adjustment in UV view after unfolding. I'll give it a go. Thankyou!
If I can piggyback on this for a general question:
I get the seams and unfolding for UVs, but what do the pins do? Also, what does UV stand for, and what is the "u and v axis"?
lexbaird:
Pinning is used in conjunction with cutting of mesh seams to help with mapping distortions that can arise. It locks down vertices, so the re-unwrapping wraps around the locked placements. It is an art unto itself finding the right combination of verts to pin to get the unwrapping desired. Sometimes it's easy. Sometimes it's hit-n-miss (in my humble opinion).
Someone else can give you more details to perform in Hex. I don't map in Hex. I use easier mapping software that doesn't fry ones brain...
Now, UV's in it's simplest terms is a two-dimensional representation of the 3D x,y,z data on a squared plane (think of a perfect squared piece of flat paper) with a numerical spectrum of 0,1 starting in the bottom left hand corner (0,0). "U" is the horizontal data representation, and "V" is the vertical data set. The center of the plane would be 0.5 (.5, .5), the bottom right corner 1,0, the top left corner 0,1, and the top right corner 1,1.
I don't remember right now why it is named UV, and not HV (It's late, and I can barely see straight). Someone else can probably shed some light on this, I'm sure.
*EDIT: Here is a good UV mapping thread we had here a while back. Lots of good info for anyone new to UV mapping:
http://www.daz3d.com/forums/discussion/984/
I believe that it was called UV because the other letters were already used, and to avoid confusion.
In other words, X, Y and Z became U, V and W (the previous three letters in the alphabet). I had a version of 3DS Max many years ago, and it referred to 'Z' depth, but that doesn't seem to be used by anyone now. We just use U and V to represent X and Y in a 2D image to avoid any possible confusion..
Just to add to what Daremok and JimmyC wrote - pins are used to pin down parts of the UV map to prevent distortion - think of pinning a bearskin down to dry out in the sun:)
UV mapping is pretty much an art unto itself, but once the principles are understood, it does make a lot of sense and is pretty easy. Although I don't personally use Hexagon's UV mapping, for a variety of reasons, it is pretty good (for a standalone modeling app) once it is understood.
Specialist UV mapping software is pretty much a must for anyone getting seriously into modeling.
Just as a demo - the first pic shows a torus UV mapped without pins, and the second with pins - that is what is needed to get a texture decently laid out.
Wouldn't it be nice if some kind Admin made this and Daremok3's heads up regarding an old thread,
into a UV/mappingsticky we've only got the one on tutorials. :)On the torus could you show where the pins are. appreciated, thanx
Sure - the red dots are the pins and the blue lines are the seams.
A rule of thumb that is common to most unwrapping is that the pins are directly opposite the lengthwise cut, one vert away from the vertical cut. On a pair of trousers, for instance, the cut would be from the inside ankle, up across the crotch and down the inside of the other leg and the pins would be located on each outside hip and each outside ankle.
This is not all there is to it - you also need to get the projection axis right - think of it as shining a flashlight onto the object - Y axis from above and below, Z front and back and X from left to right and vise-versa.
So if the seams and pins look right and its still not unwrapping correctly, change the projection axis.
There is no way of saying which is right and which is wrong - it all depends on what texture you want to apply and how you want to apply it.
With practice, you will soon get the feel:)
Roygee, thank you very much!
Only a pleasure - hope it helps:)
Please just add to what I wrote about the trousers - continue the seam from the centre of the crotch up between the buttocks to the belt - the idea is that you want it cut so that, if it were a real piece of cloth, you could lay it out flat, without wrinkles.
Something very helpful about Hex unwrapping - if you have any overlaps, which you must definitely avoid, they will show up as a brighter blue than the rest of the map when you select all the faces.
thanx roygee, didnt know about the lighter blue. this is very helpful at the moment. i have been mapping a cylinder {shampoo bottle} and i did the seams but i didnt know where to put pins and as in your example it was distorted at the top and the image is a bit stretched. will try this as soon as i finish a render
Aah, yes - I recall you asking questions about the shampoo bottle in the Carrara forum:)
Did a quick mock-up of it in Hex to see where to place the seams and pins - you can see from the first pic one of the major reasons I don't use hex for UV mapping - see the tiny dot in the bottom right corner? That is the bottle top! Hex has no sense of proportion because it forces the whole map onto the grid.
You can imagine what it would be like trying to eye-ball manually correcting proportions with a complex model!
The second one shows what it looks like in UU3D, after setting auto proportions.
The other two reasons is that it doesn't retain seams and pins after saving and re-opening, so it has to be a single-session operation and secondly it is inclined to crash when doing complex mapping.
Other than that, it has a pretty good UV mapping and manipulation capabilities:)
roygee was unable to post my response here for some reason with an image i reposted and have one more question thanx