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Animated growth is achieved via a combination of the Timeline Bar and the properties on each of the generators that support growth (Branch, Leaf Mesh, Fin, Frond, Cap, and Knot). Caps and knots grow automatically with their parents, the rest of the generators listed have their growth governed by a series of properties in the “Growth” group.

Note: The legacy generators Spine and Leaf do not support growth in version 8. They must be upgraded before they can be used in the growth system.

The typical workflow for editing growth is to first get the model correct with growth disabled. Then, run the Growth Wizard (described below) to get the basics in place and then fine tune the behavior by editing each generator's growth properties and adjusting the overall speed and timing on the Timeline Bar.

Growth Wizard

Access the Growth Wizard by selecting it from the “Tools” menu or clicking the “Wizard” button in the growth group on the Timeline bar. You will be presented with the following options:

  • Grow - The model will develop into its final form gradually with branches and leaves beginning to grow once their parents have started growing.
  • Reveal - The model will appear to be traced out into its final form. This style is commonly used when branches grow around meshes (e.g., vines on a trellis).

The first option, “Grow”, is suitable for most applications. It will set up all branches and leaves to start growing off their parent once the parent has grown a little (all “Timing” generator properties are set to “Parent”). The result is a continuous growth look where the tree organically grows into its final form.

The “Reveal” option is necessary in any instance where growing branches can't move without causing artifacts in the final production. The best example is any case where branches grow around each other or a mesh used as a stand in for a scene object. All “Timing” generator properties in this case are set to “In place”, which means once the parent reaches the point where the child originates, the child will start growing.

Note: You can mix and match these types after the wizard has finished. Take a look at the “trellis_growth.spm” example. The vines growing around the trellis use “In place” timing, the rest of the model uses “Parent” timing.
Note: Batched Leaf generators do not work with growth (they sacrifice functionality for speed). The Growth Wizard will always convert these generators to Leaf Mesh generators.

Using the Timeline

Once the wizard has finished use the Timeline Bar to control the timing. First make sure your end frame matches the shot. Then use the “Speed” control and corresponding curve to adjust how fast the model grows. All “Speed” properties on the generators are scalars applied to this central speed value. Adjust the value until the model is at the stage you need it to be in on the last frame. Growth computations naturally have a lot of variation and are subject to curve edits and node edits on individual pieces. The only way to ensure your model is at the stage you need it to be in on a particular frame is to edit the speed and speed curve.

Editing Properties

Mose generators have a series of growth properties in a group labelled “Growth”. These properties are described in detail on each generator's reference page. Use them to control the timing, speed, orientation, and all other aspects of growth for each component of the model.


Growth animations must be exported as an Alembic file; point cache formats will not work because the number of vertices changes each frame. You can use “File→Render image sequence…” to render out a sequence of frames for a preview of the animation before exporting and rendering in a third party application.


SpeedTree Modelers that support growth are installed with growth example models. Look in the “Samples” folder in the installation location to find them.

Best Practices

The following list outlines a few things to keep in mind when tuning growth.

  • Always run the “Growth Wizard” first. It sets up the basics and resets parent and profile curves to make sure you have a solid starting point.
  • Use “Focus” to single out a section of the tree. This will often make the model compute fast enough to preview a section in real-time using the Timeline Bar controls.
  • Avoid the model ever coming to stop. Either adjust the “Wobble” properties so there is always a little wobble, extend the “End” frame farther than you need, enable wind, or do all of the above. Growth animations typically look better with at least some motion in the limbs at all times.
  • Use Draft mode to drastically reduce triangle count when tuning growth.