Help for correctly unwraping a tree models

[Anonymous]

Hello guys, 

I have some question about the correct way to unwrap and uv a tree.. 

I sculpted my models on zbrush and i retopo my tree to give some good shape to work with. But my problem is about uv a complex models like a conifer tree :

1. Where to put the seams ? On trunk and branches ?? 

2. How can i have my result without any stretching texture? 

I can post some photo if you need it to see my problem... i also work with the unreal engine and my trunk is pretty nice but the branches in some place is stretching. 

Any help will be greatly appreciate! 

Vincent Bouchard

[Anonymous]

Perhaps this can help:

http://bct.me/tutorials/building-a-tree/building-a-tree-part-3-uv-unwrapping/

 Basically a collection of rings around the branches and trunk to make them independent and allow align them correctly  to the texture and seams connecting the rings to allow peel them as cylinders.

[Anonymous]

Yes i consult this tutorial but i'm not sure how to start with this : 

1. I have pre-made a zbrush trunk with a good topology.

I'm really not sure what is the best way to work and make my branches. My previous model have failed because of some bad stretching problem caused by my low poly workflow in zbrush. 

So this time i want to have my trunk from zbrush and making my branches on 3ds but what is the best way to do it? 

The branches tool? 

The way of the tutorial? 

I'm not so sure at this moment what is the best option to be sure to not stetching my texture again.. 

[Anonymous]

Post your model or part of it if you can.

[Anonymous]

This is one of my trunk mesh i have 5-6 more to do the new branches 

And here is my old mesh with the zbrush branches.. pretty bad and that's why I want to do a good topo this time 

[Anonymous]

From photos I would repeat the same I said in my first post. Send the 3d model or part of it if you want.

[Anonymous]

https://www58.zippyshare.com/v/1z4uq75J/file.html

Perfect in this you have the 1st photo (New trunk with good topo)

And 

The one of my bad tree 

Thank you for your time ! 

[Anonymous · Accepted solution]

You need two structures of seams:

• One that goes along the trunk and branches from bottom to top
• Another that produces rings for each individual branches and the trunk.

Both logically will intersect and will create cylindrical UVs once cut and peeled

Maya has a automatic UV tool for doing this, the same that UVlayout. This video shows how works in Maya. I point it in order you understand where the cuts must be done. But because you need to do it manually in Max it will take a lot longer:

https://youtu.be/K_uYHH7GHao?t=152

Once you have the cuts you need to use peel and then reorder all branches in the same direction (something also done automatically in part in Maya or UV layout)

[Anonymous]

Hi Karl, 

I restarted my trees with a good topo this time for the branches and I see how much easy this is to edit and works with. I will use this exact method to unwrap my tree thank you again for your time! I work sometime with 3ds because this is the first 3d program that i worked with but in my university we use maya so I will test the auto seams for sure. 

[Anonymous]

Hello again, 

So now i made my uv by manually cutting the seams that I want (because the auto seam don't work really nicely with my model) and I want to know if you see anything that can be better. 

Some questions: 

1. This models is a test model but is that correct to export this low poly mesh to zbrush, work on a high poly without changing the shape too much and bake the result with xnormal with the uv already done? 

2. My uv seams for the trunk make my checker to not being aligned as you can see  is that normal or I need to try something to align everything and also is my uv seams look greatly place? 

3. In the picture you see that the uv is not taking all the space in the square, again is that good anyway ? 

Again if you need the models I can give you the obj to see by yourself. 

[Anonymous]

 It very much depends of the level of detail and style of the tree.

Many times the trees use different texture for the branches and the trunk, and the textures are tiled.

Being tiled means that you can go beyond the tile of the UVs and the UV space is not relevant any more.

If you don’t want to be tiled then the texture needs to be more detailed and accurate for something that is very long.

If it is tiled means you cannot paint the texture based in zones, for example lower or higher area, but you can always swap to different texture.

For game engines they use different UVs for lighting and can use layers for created overlays over the tiled texture, something that you can do also in PC with blend material

Keep in mind your UV are heavily stretched vertically, you would lose more UV space that you think if you don’t make it tiled and remove the stretch effect of the UV

And yes, would be better if the trunk is perfectly vertical

By the way, you don’t need the bottom part of the trunk,  specially the UVs with the same size, if it is not visible.

[Anonymous]

So if I understand correctly your instruction i'm better using example 2 uv's tile and work my trunk on one of the tile and the other work with my branches. After give the scale that I want for the trunk space and the branches space and also add one texture for the trunk and one for the branches. 

I will look some tutorial and documentation about it there's alot like this: https://knowledge.autodesk.com/support/maya/learn-explore/caas/CloudHelp/cloudhelp/2017/ENU/Maya/fil...

and youtube video. 

Again thank you for your quick answer! Really appreciate your help!

[Anonymous]

Multi-tiles is a different concept. It is when we want a single UV layout using different UV tiles. In this case each UV tile will have a different texture. This is mostly for objects with very heavy texture sizes and it is not related to your case. Also you normally won’t tile the bitmap texture in this case.

I know these names can be confusing.

• Tile texture: the same texture repeats multiple times
• Tile UVs: the object is assigned multiple UV tiles and each tile has his own bitmap. No tiling of bitmaps.

In some way they are the opposite. Tiling texture is a way to use less bitmap texture but the effect will be high res because the repetition of the bitmap texture, when tiling UVs is a way to use more unique bitmap textures without repeating.

The idea of working inside of the UV tile is that you never are going to tile the bitmap texture. If you don’t need this restriction it doesn’t matter if you keep the branches and trunk both in the same UV space or not. I would keep it in the same to double check proportional sizes and proportions.

Single UV tile texture assignation is done with material Ids, not with UVs. Well, unless you use UV tiles as each UV tile use his own bitmap texture. UV tiles are considered a relatively advanced feature mostly for films and rarely used in normal assets. Until recently few programs were able to support it properly.

I think would be a good idea you take a look also to some tree models and how they are done. Currently there are hundreds of commercial plants and trees collection and many offer free samples.

[Anonymous]

Finally got it to work pretty well! I extract my branches from my trunk and i layout all on the same uv square, so now I can easily work on a high poly mesh and bake my detail on my low poly also with my new uv the texture look pretty nice without any stretch and like you as said before i cut the bottom of the trunk too. 

I actually thinking about making 2 other uv channel's 1 for my pine and 1 for my lightmap. 

The uv of maya is clearly better than 3ds and I will probably use that now. 

[Anonymous]

Yes, sadly UV in Maya are more advanced. Well, until the next Max update, I hope.

Good to see everything is improving for you.