Pull out all stops on detail and build a realistic 3D tree model from your simulation. Twigs complete your tree to a lightweight model full of intricate berries and flowers.
While growing, the tree is just a virtual data structure. After growing, it’s time to build a 3D model. Building the tree model is a two step process. Main branches are first created, followed by the placement of twig models.
The Grove builds a 3D model of the tree’s simulated branches by turning them into a curves object. Every branch becomes a curve, while every branch node becomes a curve node.
Now it’s time to add thickness to the branches. Determining each node’s thickness starts at the tips. Thickness then adds up all the way to the base. This ensures correct results at every age without needing constant user input. It does all the hard work for you.
Starting with Tip Thickness, each next node adds Internode Gain. Match Tip Thickness with the starting thickness of the twig you are using for a smooth transition. Internode Gain is usually a minute value.
Traveling further down to the base, we reach a branching point. As a side branch joins the current branch, the two don’t just add up. Both thicknesses blend naturally through an exponential formula. Branching Thickness Exponent controls the blending. It defines the character of a tree big time. Its value usually ranges from 1.5 to 2.8, with most trees around 2.4. It’s tempting to pick a low value, which adds a lot of thickness at branching points. This rapidly adds thickness to main branches and the trunk. To our mind, this looks real. Yet when looking at a real tree, its main branches are often freakishly thin relative to their length.
This tip-to-root approach provides perfect results at every age. And the Branching Thickness Exponent creates realistic transitions. The trunk seamlessly flows into the crown like in real trees.
Root Scale adds extra thickness to the lower trunk close to the surface. Root branching adds thickness to this part of a tree. Its Distribution controls how far up the trunk this effect is visible.
As a tree grows older, the branching structure can get quite complex. Although the twig system can save amazing amounts of memory, branches can also fill up your GPU quite quickly. Advanced Meshing lets you control the resolution of your branches and the resulting amount of polygons.
The trunk and main branches require most geometric detail, define the resolution of the base with Profile Resolution. A resolution of 24 means the base will be a circle described with 24 points. Especially when using root protrusions, this resolution should be kept quite high. But it makes no sense to use the same high resolution for the thin branches up in the tree crown. Reduction reduces the resolution of each branch, based on the thickness of its first node.
Most of the build parameters can best be learned by interactively tweaking them. Grow a small enough tree for the mesh building to still be interactive. Then just play with the sliders.
Twigs are the youngest branches, the new growth. While older branches are basically a structural tube, twigs are like small plants – featuring leaves, flowers and fruit. To approximate this diversity, generating twigs with software requires a matching complex user interface. This interface would never reach the versatility and speed of direct modeling.
Instead of growing a full tree and distributing leaves, it is preferable to hand model twigs. Distributing linked copies of a hand modeled twig saves huge amounts of polygons. This makes old trees and even groups of trees lightweight to handle and render. Add leaves, flowers and fruits with intricate detail yet little impact on memory. This makes the Grove trees ideal for GPU rendering.
Nothing is stopping you from using a single leaf as a twig object, it works great. For simpler trees this might just do the trick. You decide on where to take over. Model a single leaf, last year’s twig or add a generation or two. Compensate the size of the twig with the prune distance.
The Grove offers two ways to duplicate a twig model. Depending on where you will be using your tree, each has its advantage over the other.
Particle System is the default and preferred twig duplication type. It creates an object with a particle system linked to it. Every face in the object emits one twig. The rotation of the face determines the heading of the twig. This method cuts memory usage to just one twig and it is fast while growing.
Object Instances creates a lot of twig objects in your scene, all linking to the same twig mesh. This may give you more control over individual twigs. But unlike particle duplication, Blender slows down with the big amount of twig objects.
On some trees, twigs grown from apical buds are different from twigs grown from side buds. Apical twigs are often more powerful, longer and they carry more leaves. On some species, flowers appear more prominent on one or the other. Enter the name of the Apical Twig object and the Lateral Twig object. You can also use one twig for both.
The Grove distributes twig objects just like growing new branches. Only young branches have a chance of growing a twig – branches thinner than Twig Threshold thickness
Twig Chance controls the amount of side twigs – creating denser trees.
Fine tune the scaling of your twig model with Twig Scale. For realism, the twig model should be to scale. But every tree is different, and whatever looks great, is great!
After growing and building your tree with the Grove, you get several objects. One object represents all the branches. The other two objects duplicate both the apical and the lateral twigs. If you move, rotate or scale the tree, be sure to select all three objects before transformation.
The twigs system provides huge savings in memory and is quick to render. But the amount of polygons can have quite an impact on viewport performance. There are two solutions to this problem. Either move the two twig duplicator objects to an invisible layer which you enable at render time. Or the other option is to change the way Blender draws particles.
To do this, select one of the two twig duplicator objects and head to the Particle Settings. Scroll all the way down to the Display Panel. Select Circle and increase the Draw Size to match the size of your twig. Repeat this process for the other twig duplicator object. Viewport should be smooth again. While at render time, Blender will use the twig object.
Learn more one twigs and how to create your own, read Creating and using twigs.
If you want to use the tree in another 3D software than Blender, you will have to export the model. Blender exports 3D objects to industry standard formats like OBJ, 3DS, FBX and DAE.
Let’s try exporting an OBJ, a well supported format. Select your tree object and its twig duplicator objects. From the File menu, go to Export and select Wavefront (.obj). Browse to your preferred location and check the export settings at the lower left. Check Apply Modifiers and also check Selection Only. Export your OBJ and import it in whatever application your project is in.
Check if your application supports duplicating objects at the center of each face. Just as Blender does through its particle system. You can then set up twig duplication to enjoy all the benefits of twigs. To do this, export the twig as a separate object. And be sure to uncheck Apply Modifiers when exporting your tree. Now you get the branching structure, and the two twig duplicator objects.