Tips For Modeling Better Trees
By Neil Blevins
Created On: May 3rd 2020

Modeling trees can be quite a difficult task, and while there's software out there to help you do it faster like speed tree, sometimes the tree you're making is so unique or needs to be so detailed that there's really no good automated way to do it, you just have to model by hand! In these cases, here's a few tips I've found helpful to not only speed up the process, but produce trees with real character, so they don't look malformed or too simple.



A big thanks to all my tree modeling partners in crime: Gaston, Greg, Nancy, Matt, and others for discovering and helping to develop these tips. For this lesson, I'll be using 3dsmax for modeling, but I also make a number of notes about maya, and the overall idea will work in any 3d app you choose.

1) Use Splines Or Curves, Don't Extrude Faces

There are two basic techniques for making branches by hand. One is to extrude faces on your trunk to create the branch. The second is to make the branch separate from the trunk, and then attach them together.

I favor the second technique. And the main reason is because with the extrude faces technique, it is really easy to accidentally produce flattened branches (branches that have a flattened cross section).



What you want is a nice round cross section to your branches.



Much better to use something like cylinders that just interpenetrate the geometry, to guarantee the branch's roundness.



Cylinders are fine for a straight branch, but for a curved branch, you can also use splines (3dsmax) or curves (maya).



In Maya, create any sort of curve you want to define the branch, then use the extrude function to extrude a cylinder along the curve. Make sure the extrude has enough divisions so that the cylinder accurately follows the curve.

In 3dsmax, a renderable spline (A) will always keep the cross section round, even when you're pushing and pulling the shape of the branch around (ie, moving the knots of the spline). A variation on the technique is to use the plugin Splinemesher by Grant Adam, which will allow you to taper the branches without collapsing the geometry to an Editable Poly (B).



2) Don't Attach Anything Until The Tree Looks Good

So when you use the technique where the branches aren't actually attached to the trunk, or each other, you will eventually need to attach them to form a single smoothable mesh. But wait as long as possible before completing this step. This is because, once the branch is attached, it becomes way harder to move, especially if you're trying to keep that nice round cross section we talked about. So be really sure that the tree is awesome (and all of the steps below have been considered) before starting to attach all the branches together.

Here's the penetrating branch.



The branch is 6 sided, so I delete two faces on the trunk to create a 6 sided hole, and then I delete the part of the branch that intersects with the tree.



In maya you can build the faces to connect the two holes together, in 3dsmax, attach the branch to the trunk with the attach function. Then select the perimeter of the hole in the branch, and the perimeter of the hole in the trunk, and click on bridge, which will connect the two.



And here's the smoothed mesh after I apply a turbosmooth in 3dsmax.



3) Different Number Of Segments for Trunk, Branches, and Small Branches

As you move from working on the trunk, to the major branches, to the tiny branches, use fewer segments on your splines or cylinders as you progress down. Not only will that make sure that you're not adding too much detail on the tiny branches, but it will also make it easier to attach the branches to each other, since each stage will have holes with fewer edges. One rule of thumb may be Primary Branches: 8-10 segments, Secondary Branches: 6 segments, Tertiary Branches: 4 segments. These are just suggestions, come up with your own favorite numbers that generally follow the pattern.



4) Does The Tree Look Good From All Angles

If you've ever tried to draw a tree on paper, one big issue is a tree is a very complex 3 dimensional shape. So translating that into a 2d medium, a piece of paper, is difficult. Turns our replicating branches in a 3d medium such as 3dsmax or maya isn't super easy either, since you're building in 3d, but you're using a 2d representation of a 3d world (your flat computer screen). You may have a branch structure that looks great from one angle...



But rotate the view, and oops, all of those branches sit on a single plane, instead of pointing out truly in 3d.



The result is a very boring and unnatural tree. So when you're making branch clumps, make sure that you look at them from many angles, and that it looks good from many angles.





I tend to make sure the tree looks good from the front, left, right, back, and four 45 degree angles too.

As well as making a better single tree that looks good if you travel around it, you can get 4-8 good looking trees from that single tree just by rotating it, which means you have to build fewer trees to populate a forest. No one will know its a single tree just rotated around!

5) Twists

Instead of just having trunks and branches go straight, consider adding a slight twist to them. This is a really nice detail that gives a beautiful flow to your trees and branches. This twist is pretty extreme, but even a very subtle one can add a nice feel.

Either twist by hand, or in maya, use a twist deformer, or 3dsmax, a twist modifier on the trunk and branches before you attach them.







6)
Add Irregularity (and Elbows)

Ok, now that I've spent so much time telling you to make sure the cross sections are circular, I'm gonna tell you the opposite. The key is you don't necessarily want all the cross sections to be round everywhere, but start with everything being round, then CHOOSE where to break the rules.

So in a few key spots, after you're pretty sure you want the branch in the spot it is, collapse it (3dsmax) or delete history (maya) and play around with some of the vertexes to start creating some flatter areas to avoid everything looking super round. These areas frequently happen where there's a change in the direction of the branch. I call them elbows. Here's some examples of elbows on a real tree...



Here's an example of a branch that's perfectly round everywhere. It's boring...



Now take spots where the branch changes direction and push and pull some of the verts to create elbow shapes (look at your own elbow for reference). Here's the results...



Far more interesting looking. You can even go a step further and flatten a few areas ever so slightly, and mix that with some twist to get some more complex shapes.



If you want to push it even further, the "elbow" spots I've been talking about are frequently caused by a branch falling off (or cut), so these elbows are a perfect spot for placing branch nubs (either in modeling or in texture).



7) Add Roots Around Base

Remember, a tree is never just a cylinder stuck into the ground. Trees have roots. So make sure that at the base of your tree you have the beginnings of a root system. You don't have to create all of the roots, but make sure you see the root system start above ground, and then add a little extra underground. That way you can move the tree up and down slightly in the ground without worrying about the tree accidentally unnaturally floating above the ground. Maybe make an extra foot of tree below ground so you have some leeway.





Conclusion

Hope these tips add some extra life to your next tree.


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