Units and scaling

The SpeedTree system, from the Modeler through to the Runtime SDK, is unitless. However, trees in the SpeedTree model library are modeled where one unit represents approximately one foot. If a conversion is necessary, there are a few possible approaches:

1. Scale the model upon export to the .stsdk format. The Modeler's export dialog has a geometry scalar text box to support this.

2. When creating instances of a given tree, multiply the value assigned to SInstance::m_fScalar to compensate for the units difference. The tree will still be in the same units, but the culling and shader systems will interpret them with the correct scale value.

3. Scale the tree in the Modeler using either Tools > Scene unit conversion or Tools > Arbitrary scene scale.