#11 - Tree Sculpting Test
Trees are going to be an important part of the scene. Not only do they fill up the vast empty landscape, they sit in the foreground and help to frame the edges scene, and will eventually add some motion and make the scene feel more dynamic and alive.
My terrible placeholder tree is obviously not going to cut it, even with nice textures applied to it, so I have had to look at some of the potential techniques for creating stylised trees.
SpeedTree
I have used SpeedTree a few times in the past for different projects. I love how easy it is to generate trees, and how much freedom there is to sit and tweak parameters to get the results you need.
In this first image, from 2017, I used SpeedTree for the simple cartoony trees, as well as for the small purple plants on the ground.
In this second image, from 2019, I used SpeedTree for the tree that hangs over in front of the open doorway, as well as for the bamboo in the background.
I also used SpeedTree to make my placeholder from the previous posts.
As implied by the name "Speed" is one of the major benefits of using SpeedTree. It produces usable results and variations far quicker than any other method I've seen.
Another major benefit is it's baked "Wind" parameters, which provide all the vertex colour data that UE5 needs to simulate much more detailed wind that can affect the trunk, branches, and leaves individually and realistically.
However, while the software has tools to bend and warp the large-scale geometry into more interesting shapes, it lacks much in the way of adding smaller, sculptural details.
ZBrush
I have never tried to sculpt trees in ZBrush before, so I looked at some tutorials about how to get started. Some of the methods suggest starting with a base mesh in Blender, before sculpting in Blender or ZBrush.
However, the method I personally found far more efficient was to complete almost the entire process (minus foliage) in ZBrush, starting with ZSpheres:
- ZSpheres for basic trunk and branches
- Smooth and Sculpt General Shape
- Sculpt small details
- Remesh to get low-poly version
- Export to Blender to add foliage
This method is by far the slowest, but I think the amount of detail and character you can pack in more than makes up for it.
I may have gone a bit overboard with the "Wonkifying" pass at the end, which could end up making the repetition of this asset way too obvious. Generally though, I'm quite happy with how it's turned out, I think it's a decent standard to try and aim for with the other trees I need to make.
However, I've yet to bake this to a low-poly.
It's a very tall object, so getting a good Texel density and avoiding seams in the texture could be an issue. One way around this might be to give the tree a unique normal map, but then rely on a second UV set and a tiling texture to add in sharper, close-up detail to the trunk.
Additionally, replicating SpeedTree's wind effect will take more time, with the vertex colour data needing to be painted or generated in another tool, along with specialised shaders in-engine.
Foliage
Foliage is something I've yet to attempt properly, but I have two methods I'd like to try:
Both methods rely on billboard leaf cards, but produce much "fluffier", "blobbier", more painterly looking trees than SpeedTree's default (generally more realistic) card-placement.
Both methods also rely on editing the normals of the cards to get a more uniform shading effect. They do this by projecting the normals outwards, so the mass of cards shade more like a single spherical mesh.
The Stylized Station version uses a shader to turn a simple blob mesh into billboards, and as a result gives a lot more control over the effect in-engine, but also has considerably more overdraw, making it more performance intensive.
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