How do you Unwrap a Cone for Squar Tile Texture

Hello3D

Hello Polycounts I am a little stuck on an unwrapping problem.

I am making a building that has 2 different types of roofs on it. One is a regular slanted part of a roof you would see on lots of house and the other is a cone type roof. (building is semi stylized)

All the buildings in the scene will use the same tillable texture for the roofs for cohesion with some differences like hue and saturation. The problem is I don't really know how to unwrap a cone shape to use the square tillable texture without getting crazy stretching problems.

Is there a good way to unwrap cone shapes or other shapes that tapper to avoid stretching?

Here are 4 test attempts I did at unwrapping a cone shaped object, all using different methods.

First one is Cylindrical Mapping. Kinda distorted up the base and gets really warped near the top. Also stretches out the squares.



Second one I tried modifying the first to look more like the shape of the cone. Lots of stretching.



Third I tried a planner map from the top and then pelt mapping. Extreme stretching towards the top.



Forth was Unfold Mapping. This gave me the least stretching but each piece of the cone doesn’t fit with the other and if I were to stitch them it would cause stretching. Also if I were to use a tilable texture of square roof slats the roundness created by the unfold mapping would really mess it up.



If anyone has any insight on what I could do to get this to work I would really appreciate it. If there is no real way to get it to work with a tilable texture like I want and it has to have its own unique map it would be great to hear what would be the best way to unwrap it for that.

Thanks everyone

Malus

Does every face need to be unique? If not unfold map a section of the cone, maybe 90 degress, stitch any breaks, ther shouldn't be that much noticable sretching and copy it around 4 times.

Really depends on the role of the asset as to how you do it. Texture resolution, what its used for, how close to camera etc..yadda yadda...

Mark Dygert

Planar from the top?

MagicSugar

How I'd do it in Maya. Conceal seam side away from end user. But if the seam bothers you, add another loop near the tip and planar map - should give your more adjusting leverage.

EarthQuake

This image, but without the two vertical seams, is really the optimal way to it, you'll get a little bit of distortion, but not enough to really matter

Heres a quick unwrap in modo, really i cant see how any other method than this would be usable. Top down planar would give you some terrible stretching. If this was a very small bit, and not very tall, then i guess it probabbly wouldn't matter, but even in that case planar wouldn't really be a good option. Hell i never use planar for anything, havent in years. With auto-unwrap(select seams, unwrap) + relax you can "planar" type projection with a lot less work, and less distortion.



Also malus' suggestion of cutting out 1/4th and duplicating it is a good idea, this really wont give you much better distortion than the above image, but will save texture space, and be an easier shape to pack into your uvs.

[edit] Whoops it looks like you want to use a tiling texture on this, and in this case the only real solution would be a simple cylindrical map this this:




Now, personally i wouldn't use a tiling texture for this sort of object, i would do as malus suggested, map a 1/4th sliver of this uniquely, build a highres model of some trim on either side, and tiles in-between, and project that down onto your 1/4th mesh. Even if this is just for hand painted stuff, it would be a good guide to paint over, because its going to be a pain to get straight lines etc on an unwrap like this by hand.

Also it might help if you could post some reference of the roof style you're going for.


Ok edit again, here is another posibility if you really want to use a tiling texture, just do an auto unwrap on 1/4th, alight it so the center is straight, and then straight up the vertical edges as well. You'll get a little worse distortion towards the outer edges, but it may not be noticable. I would also model in some trim peices in the low poly here, to break up the seems, so that you do not see where the 1/4ths meet.

Mark Dygert

Just out of curiosity I created a cone (not a mangled cylinder) and applied unwrap, just to see what kind of default unwrap 3dsmax applies. This is what I saw.

There seems to be a bit of distortion but it would let you paint straight horiz lines without distortion or anti-aliased lines. You could possibly start to minimize the vertical distortion by scaling in horiz the each row of verts starting from the bottom to the top, so it looks a bit like EQ's last example, but unique.

I guess it really depends on what you'll be painting on the cone...

Allert

Hi,

This is what I would do:

Planar X or Z map your cone, cut UV's in length, flip one UV-side, re-attach Uv edges on one side, and do an unfold operation, and you'll hopefully end up with something like this:



This would work only for a coneshape. a sphere will be a more tricky primitive to map.

warby

if you are intending to use a Grid like roof tile texture ( like i presume you do ) than this is the best way to map it:

wailingmonkey

too bad the distortion is so ugly along the middle tri there.

EarthQuake

Yeah, here is a bit more practical example.

Using some trim to hide the seams on the 1/4th model, you can get some pretty good results, there is some slight distortion near the uv seems, but nothing too bad. Also, you can shift around the uvs on the different parts, to get different detail from your texture as well.


And using the basic cylindrical map, you get a seam on every face at the top point, some pretty bad distortion, and the tiles change size pretty drasticly, IMO not a very good solution at all.

Hello3D

wow thanks guys for all the awesome feedback. I was worried that this was going to be just a dumb question and ignored. The good things I heard about polycount defiantly seem to be true

Think I will go with the idea suggested by Malus and use some trim to hide the seams like EQ did. The extra geo would be worth it I think.

Thanks again everyone for all your ideas.

Harry

I'd probably split it in half and relax it, put the textures on and use the channel-bake trick to fix the resultant seam.

but I'm a faggot so who knows

MoP

The nice thing about MagicSugar's unwrap (which is similar to what I'd do - although I'd take the top and left seams right to the exact UV border) is you can then make a texture which tiles on a 90 degree rotation (so the left edge of the texture matches the top edge)... that way you will have no seam at all

Mark Dygert

I like MagicSugar's approach however it didn't take into account the 2 extra loops and the slightly deformed shape, which would make getting to that nice straight edge problematic. The only two ways I can think of would be to make the simple cone, unwrap it, and then add/deform the loops after. Or do a lot of edge straightening?
But then it would probably create some ugly stretching and any attempt to relax it would blow the seams, maybe just relax a selection and hope to keep the seams intact with minimal stretching... =/

I'll definitely keep that approach in mind for regular cones but the extra loops... make it tough.

wailingmonkey

nice suggestion, MoP... seems a bit more effort/thought into the texture end to
get the 'point' looking right, I spose, but much better with minimizing deformation
on the actual UVs.