I could use some advice on how to rotate a section of a UV map.

After using Poser for years, I finally decided to to have a crack at modelling. My first project is a coffin, and I'm happy with the resulting mesh, but I have a problem with the UVs.

The coffin has two groups "main" and "top" (lid), the two groups share the same material "main". The orientation of UVs on the top of the coffin run side-side, and those on the sides of the coffin run front-back.

I want to change the orientation of the UVs on the top only, so that they run front-back. How do I do this?

The tools I have are Poser PP2012, UV Mapper Classic, Roadkill 1.1, and Hexagon 2.5.1.79. I'm very new to the last two.

You can shift 90 degrees by using the VU setting in the material (where it says UV)

Quote - You can shift 90 degrees by using the VU setting in the material (where it says UV)

Yes, that will likely solve the problem for the top, but then you would have the problem on the bottom, like with a rubik's cube, where solving one side destroys another. I think you can do it in uv mapper (select some uvs and rotate them), but i do not know the details.

millighost, you hit the nail on the head, it's the a rubik's cube problem. UV Mapper Clasic has a tool "Rotate" but using it, either with a section or the whole mesh selected, does not seem to have any effect.

I could fudge it in Poser by creating an extra material and using VU,  but I would rather fix the UVs in the obj.

I would regroup it with a couple material zones because that seems easier.  Remapping it is certainly a more robust option.

markschum, I may have to do that, if no solution is forthcoming, but I would much rather learn how to fix it, rather than work round it, as it is likely to be a problem that I keep running up against time and time again. If I knew a way to rotate the entire UV space 90 degrees, I could split the obj into 2, fix the offending part, then reassemble as one obj, but I don't even know how to rotate the UVs for an entire obj.

I'm not quite sure what you're after, but tricks like this sometimes work:

1. separate the parts in the modeler,

2. counter-rotate the relevant part and re-save only that part as OBJ;

3. Use UVmapper on that OBJ and save the result;

4. Bring that mapped OBJ back into the modeler and re-assemble it with

the other part;

1. Don't let UVmapper alter that part again after it's re-assembled.

By counter-rotate, I mean turn the part CW in this step if you want the UV map to end up as CCW from where it originally was.

Got an aspirin?

Although I achieved the result I wanted, I did rather struggle to get there. So any methods, tips, techniques, and advice on this, will still be very welcome.

Seems like your solution pretty much nailed it... Ockham's advice would be the route I would have taken. UVing is inherently a struggle, especially if you don't have a robust array of tools at your disposal. Wait until you get into organic models!

As an aside you might want to consider putting some micro bevels on the planar edges of your hard edged objects to catch highlights. Just be aware that you need to set smooth polys to off and the crease angle of your model to 0 in its properties. Otherwise the bevels and poser's smoothing will cause artifacts in both the preview and renders.

christ, never thought I would be offering poser advice to lesbentley!

Les, UVMapper Classic's rotate command rotates the model, not the map, but only as far as the mapping "camera" sees it, if that makes sense. The idea is that you rotate the model as far as UVMapper is concerned, and then re-map. The spatial visualisation capability required to do this may be beyond mere mortals, however. Your chances of getting it right first time are minuscule. :) To further confuse matters, there's an export option which retains the model rotation setting, but since there's no 3D preview you'll need to be really on the ball (or plane, torus, cylinder, box etc.) to get the results you expected.

If you think you may get into modelling to any extent, you may want to consider buying UVMapper Pro, which will do all of this and more, better, and with less fuss. It's the first 3D application I actually paid for, and I've never regretted it. 

addendum... Doesn't Hex have built in UVing? Pretty sure the most recent release has features like UV relax etc.

Quote - The idea is that you rotate the model as far as UVMapper is concerned, and then re-map.

:woot: Haha! Enlightenment. I was wondering why I did not see any change. After Rotating I need to remap, never thought of trying that. Perhaps it does make sense to read the manual some times. Simple when you know how. After your explanation I got it right first try, though perhaps that was just beginners luck. Thanks.

Quote - Doesn't Hex have built in UVing? Pretty sure the most recent release has features like UV relax etc.

Yes, indeed it does, and it was in Hexagon that I finally managed to fix it, but I'm not too familiar with the techniques or terminology. To me "relax" means have a glass of wine and a cigarette whilst you are trying to figure out what to do.

Your version of relaxing definitely sounds  more "Relaxing"... What relaxing a UV map does is akin to smoothing out and flattening a wrinkled sheet over a bed I guess. it eliminates or minimizes distortions in the map by attempting to equalize the edge layout of the map. It helps to eliminate bunched up polys that you often see at the edges of map regions, These bunched up polys in the map make a mess of your texturing attempts and often make glaring seams in your textures (or so I've found).

Here's a really tech explaination... http://en.wikipedia.org/wiki/Bellman%E2%80%93Ford_algorithm

You might be well served by these Hex tutorials, they look pretty good...

http://www.geekatplay.com/hexagontutorials/

Can't really offer too much specific advice about Hex, as it's not my weapon of choice (I have the latest version but it's incredibly unstable on my computer).

cheers

Dunno if you have looked at Blender?.  but its uv mapping is pretty awesome, can move anything on the map and "fixing" ur problem would have been just a case of selecting what you wanted to rotate an doing it, Hex is a fantasic modeler but the uv mapping is a bit odd sometimes

Quote - I managed to do it In Hexagon

Looks nice, but allow me to point out that in a real coffin, the grain wouldn't run along the sides continuously like that. Grain like that suggests that the coffin was cut out of a single block of wood, whereas a real coffin would be made out of planks, all of which would have different grains. The way to do this would to be have all the different faces of the side in their own UV space. eg something like this: