This is Part 3 of my tree building tutorial. you can access the other parts from the bottom of the page.
Unwrapping the tree is a fairly simple process that can be broken into a number of steps. Firstly load the level 0 mesh into max and place a uv checker material on so you can keep an eye on the uvs as you unwrap. I use a UV checker with both circles and squares as it’s often easier to perceive UV stretching issues from circles rather than the traditional squares. Feel free to grab my texture by right clicking and saving the image below.
To be safe it’s a good idea to remove all the UVs from the object by converting it to be a mesh object, then using the UVW remove utility found in the tools menu. Once you’re done convert the object back to an Editable Poly and add a UV Unwrap modifier to your tree.
Start with the trunk, find a natural seam up the length and select the UV edge loop, now under the Peel roll-out select ‘convert to seams’ and the edges should change to a blue colour indicating that they’re now to be used as seams. Now select the border around each branch and convert them to seams. Repeat this process till each branch has a UV seam at the point where they join the trunk. You can check that the trunk is separated by switching to UV face mode, select a face on the trunk and then hit Expand face selection to seams. If everything is ready only the trunk should be selected.
If so then hit ‘Pelt Map’ and then Start Pelt. Once the trunk is flattened open the Relax settings and choose relax by face / polygon and then press Start Relax. If all it well you should have a nice neat unwrapped trunk. To try to be efficient with UVs I then sliced the top half of the trunk off and made it a little smaller on the UV tile as I knew the camera / player was never going to be close to the top of the tree.
Now it’s a case of repeat this process for each branch. To repeat firstly select an edge loop on the branch and covert it to be a seam. If your branch divides then add a seam around the join and another up along the length.
Now expand the face selection to the seams.
Pelt map the branch.
Relax the UVs.
You should get a result something like this
I worked my way up the tree and temporarily stacked the branches up in order so I knew which were up top and which were down near the camera level.
Now I used pack to scale just the elements from the top portion of the tree into the UV tile and have them all scaled and normalised. I then rearranged them into the top third of the tile.
Now select the remaining elements and pack them. Before you deselect them move them back off the UV tile and place them manually in the bottom two thirds of the UV tile. Again this is to place move texture resolution down at the bottom of the tree rather than up a the top where it matters less.
This video shows the process of defining seams and unwrapping branches
In the next part we’ll paint the textures in Mudbox.
I’m a highly experienced freelance CG & VFX Artist. In the Commercials world I’ve led many award winning projects; both as an onset VFX Supervisor and as a CG Supervisor. I’m now branching out into Film VFX and am currently at Double Negative as a 3D Generalist. read more