UV Unwrapping

[TyVole]

According to the product description on the Blender3d Web site, Blender has a "UV texture editor with various mesh unwrap modes." When they say "various unwrap modes" are they refering to the capsule unwrapper? Or, are there other means?

P.S: Thanks for all the wonderful help I've received from Blender Users as I try to put my arms around this terrific program!

[theeth]

Well, it says various, but...

To access the UV mapping functions, enter face selection mode (Fkey), select all the faces (Akey once or twice) and select one of the unwrapping options in the menu (Ukey). The unwrapped faces will be displayed in the image window (Shift-F10).

Martin

[ec2]

I was curious as to why v 2.25 and v.2.26 don't have Spherical as a UV calculation?


I have a related question. I have downloaded Strubi's Unwrap script and also the Capsule Unwrap script. I read in one of the posts here that Strubi's is superior to the Capsule Unwrap script, in most cases.

I guess I'm really tring to ask what is the best method/script for Blender users to unwrap and texture? I've seen many posts and I've seen a great tutorial by IamInnocent on how it works in Blender, but I really havent found a real world application of unwraping for texturing in Blender.

Any gurus out there with suggetions and or example .blend files?

[crazymopho]

the Sphere uv calc will be back in the next release

[Jamesk]

Originally Posted by ec2 I was curious as to why v 2.25 and v.2.26 don't have Spherical as a UV calculation?

There was a silly bug left in it from v2.23, and since it wasn't fixed I assume they decided it was better to leave it out completely for the time being.

I have a related question. I have downloaded Strubi's Unwrap script and also the Capsule Unwrap script. I read in one of the posts here that Strubi's is superior to the Capsule Unwrap script, in most cases.

That is correct, but that is assuming you can actually get Strubis script to work. I had it running _once_, but never again... The capsule unwrap is really only useful for things that are shaped as cylinders, and when you don't care about how the top and bottom caps will end up looking...

I guess I'm really tring to ask what is the best method - - - havent found a real world application of unwraping for texturing in Blender.

The best method is none of the above, really. Of course it depends on what kind of object you are trying to unwrap and what sort of results you are looking for.

..::GENERAL THOUGHTS to anyone interested::..
--- n.b: I only talk about texturing for stills/animation rendering, high-poly, not gamemaking which is another ballpark ---

Q1: Why unwrap at all?

- A: If your model is anything else than a primitive cube, sphere, plane or cylinder (which is usually the case, if not - work on your modeling skills a bit more before worrying about uv-mapping) then UV-mapping is essential to make things look really good. If you are going to animate your model, it's also vital to have UV-projected texturing since they will be able to deform along with your model. But it is just as important for stills as well.

There are three major issues associated with unwrapping that one can never escape: 'stretching/pinching', dealing with 'seams' and finally 'overlapping'. As long as we are dealing with non-trivial models, you can think about this in terms of "what's the best way to peel an orange?"

This may sound strange, but I have found it to be a good analogy. When I peel an orange I'm basically doing the same thing as when unwrapping a 3D-model. I change a three-dimensional topology into a two-dimensional one. First of all I have to open up the skin somewhere, usually by pushing my thumbnail through it - in 3D-modeling you have somewhat more elegant methods, more like using a knife.

Anyway, no matter how you peel the orange, you will have to cut through the skin. That will result in a seam, or, if you will, an edge, since the skin isn't infinite it is bound to get a boundary when flattened out on the table. As long as I leave it on the orange it is in fact an infinite surface, or at least without boundary - but then it is 3D and not "paintable" in 2D.

Now, you can choose your desired way - either you make the cut as small as possible and the you sort of "undress" the orange, getting on big piece of skin. It is however not easy to make it flat - you have to squash and stretch it quite a bit. You will end up with a very deformed skin, which corresponds to 'streching/pinching' above, and some parts will probably also overlap, or the outer rim will have to be torn, making new seams.

If you choose the other way, you will cut quite a lot of small bits instead of one large. In that case, there's no problem making the individual bits flat. They will probably be almost perfectly flat without you having to squash them at all. So you got rid of the stretch and pinch, but ended up with a huge amount of seams (or edges/boundaries).

The above blabber illustrates what UV-unwrapping is all about. You need to opimise the process to minimize the number of seams as well as the overall amount of stretching/pinching (I'll just say 'deformation' from now on). The final result of excellent unwrapping is when each little part of the model gets its designated part of the texture projected from an ideal 'full-frontal point'. This is not a trivial task, most of the time.

Deformation results in the texture being 'warped' in various ways when rendered. This is a bad thing. Seams result in sudden 'cuts' in the rendered texture, which is, of course, also a bad thing. Overlapping results in problems with certain features of your texture showing up in more places than you intended, since several different parts of your model end up using the same area of the texture. This is what leads to lipstick ending up not only on lips but also on collars, for instance =)

2. Preferable UV-methods

- A: First of all you should create a good starting point for the texturing already while modeling. If you plan ahead, you can make sure that unwrapping will be as painless as possible (it will always be associated with a slight touch of torture though). This means, in practice, that you will make and assign various materials to different parts of the model as you build it. That makes it easier to separate its features later. It's not at all necessary to make these materials look 'right' - just slap on some color to make it different from its closest neighbours.

While you do this, don't forget that most things in real life actually has real seams. Exploit that fact. If you model these seams, you can easily make sure that the seams in your UV-map matches those in the geometry, thus making 'seaming' a non-problem - it actually turns into a 'good thing'. Remember - you cannot peel an orange without making seams, so just accept that you will get them and make sure you give your object features where the seams can be hidden - in clever places where people won't see them.

So far we haven't used any particular UV-mapping tool. The things described above apply to all forms of unwrapping, no matter what particular technique you are about to use later on.

What's next then? If you use the built-in UV-mapper in Blender you will want to select various parts of your model and project UV-coordinates to them. The selecting will be quite easy since you have assigned different materials to your model. Use the 'select' button below the 'material indices' thingy in the edit window. Hide the other parts of the model. Hide everything that's left except for those polygons that can be aligned to the view without to much perspective distortion. Map them using the 'from window' function. Then work your way through the entire model until everything is mapped. The most important part is to use flat projection 'from window' at all times after having aligned the current part to your viewport.

Unwrapping a complex model, organic ones in particular, is a very very painful task indeed, especially using the Blender-only method. Make sure you have some good refence textures to play with, preferably some bitmaps with finelined grids and different background colors, then set your viewport to 'potato mode' (ALT-Z) in order to see what's happening. This will also reveal any problems with seams and distortion instantly as you orbit around your model. And keep those mild sedatives handy!

Automated methods such as Strubi's unwrap and the capsule unwrapper have their own respective issues. Strubi usually results in quite a lot of seams, whereas Capsule results in quite a lot of stretching, but only one seam. In my opinion, Capsule is pretty useless, at least if your model deviates from the generic cylinder shape too much - which most models do. A head, for instance, will get a lot of stretching under the chin, on the sides of the nose, on the upper part of the forehead and so on.

Is your model fairly cylindrical? Use Capsule and possibly tweak the result manually.
Is your model sort of 'mechanical'? Use Strubi (if you can get it to run). You will get seams, and also stretching - but the deformation is usually not too obvious.
Is your model organic and irregular? Well, either do everything manually as described above or try another application.

The currently best, and free way, to get top-notch unwrapping is to use Wings3D and the Auto-UV plugin (it's built-in, so there are no extra installations or downloads). You still have to make all the considerations mentioned above while modeling and while unwrapping, but the plugin helps a great deal by supplying methods for making cut markings, projection, seam-minimizing and stretch-optimizing. You can also easily export painting templates in anything from very small to very large 2D bitmaps.

Auto-UV is not an automagical tool, though. It's not a simple one-click solution. You have to know what you are doing, and you should consider the unwrapping procedure while modeling, just as I mentioned earlier. And depending on how you cut and split your model, you can get any result ranging from 'disaster' to 'hey wow!'

...:::...
Thank you for reading the longest post I've ever written. Hopefully it's been informative enough.
------------------------------

[Serialsiner]

The technique I use for UV mapping and "easy" unwrapping is the export of my models with the Obj toIO.py script, then I unwrapp them in a freeware called UV Mapper by Steve Cox, that allows the unwrapping of models by group of vertices or material indices.
I can edit a texture map with that, then I import the obj. model in Blender with the script and hit UV in the Material window . That's all that simple

Serialsiner.

[ec2]

Jamesk, Serialsiner,

Thanks to both of you for replies. JamesK that is a post worthy of saving as a text file! Lots of info in there. I really appreciate you taking the time to help me and countless others I'm sure.

Serialsiner, just as Jamesk mentioned, Wngs 3D does seem to be the way to go. I have UV Mapper also, so I'm going to really get to work on learning both soon. I played with Mapper before and liked it, and I've read much about Auto UV in Wings so I have pretty good options to work in conjunction with Blender.

Thanks again.

[Serialsiner]

Jamesk, please remember me how you do unwrap in Wings 3d.

Serialsiner.

[Jamesk]

Originally Posted by Serialsiner Jamesk, please remember me how you do unwrap in Wings 3d.

Ugh. That would mean another long post... Maybe later

[Bischofftep]

Jamesk!

Thank you for taking the time to write that extremely informative post! There are still lots of "okay, but HOW?" moments in it, but like any technique worthwhile I figure the real answer is "try and see."

Thank you again for the writeup!

-Bischofftep

[SHABA1]

Anyone know where I can get strubi's unwrap now. The link seems dead.

[TyVole]

I was able to find polmap.blend here:

http://honk.physik.uni-konstanz.de/~strubi/3d/python/

But I couldn't unzip it properly.

This .pdf contains the actual polmap.py script:

http://www.blenderbuch.de/tutor/python3/Python3_Eng.pdf

I haven't tried running it, though

[seval]

Question for anyone who knows. I want to try Serialsiner's method. Where IS the Obj toIO.py script ? I have been trying to find it with no luck.

[theeth]

http://www.ualberta.ca/~cwant/blende...O_wings_fix.py

Martin

[seval]

Very cool. Thanks.

[seval]

Serialsiner wrote

The technique I use for UV mapping and "easy" unwrapping is the export of my models with the Obj toIO.py script, then I unwrapp them in a freeware called UV Mapper by Steve Cox, that allows the unwrapping of models by group of vertices or material indices. I can edit a texture map with that, then I import the obj. model in Blender with the script and hit UV in the Material window . That's all that simple

Wow. I love that method !!! I like the fact that UVMapper allows you to change the mapping properties which can then be imported and textured with a map made directly from the coordinates. Thanks.

[Apollux]

This may seem way too dumb, but could anybody tell me this: How to get the 2D template from a model?

I mean, the instructions given so far (as i understud them) are for mapping an already painted texture into a model, but how do you guys get the base template to create such texture with a 2D painting software?

Maybe I'm blind or in serious need of a UV Mapping/Unwrapping tutorial... or both

[TorQ]

The basic way to do this is just to take a screen grab of your Unwrap window. Paste it into a new layer in your paint program. Then in the image editor I usually delete the background color just leaving the wireframe. Create a new layer underneath the wireframe layer to paint the texture on.

Recently, someone was kind enough to create a script that created an image of your UV unwrap so you can just open it in your image editor. That script can be found in the Python forum.

TorQ

[ec2]

Here's a a good reference thread from CGTalk
view thread

[ec2]

Originally Posted by Serialsiner The technique I use for UV mapping and "easy" unwrapping is the export of my models with the Obj toIO.py script, then I unwrapp them in a freeware called UV Mapper by Steve Cox, that allows the unwrapping of models by group of vertices or material indices. I can edit a texture map with that, then I import the obj. model in Blender with the script and hit UV in the Material window . That's all that simple Serialsiner.

SS,

I played with youe technique above this evening. I must say once I understood how it all worked I was pleased. Now I can concentrate on building good textures and actually map them correctly.

Thanks again.