A BillboardA textured 2D object that rotates so that it always faces the Camera. More info
See in Glossary asset is a collection of pre-rendered images of a meshThe main graphics primitive of Unity. Meshes make up a large part of your 3D worlds. Unity supports triangulated or Quadrangulated polygon meshes. Nurbs, Nurms, Subdiv surfaces must be converted to polygons. More info
See in Glossary. Use it with the Billboard Renderer to an object that is distant from the CameraA component which creates an image of a particular viewpoint in your scene. The output is either drawn to the screen or captured as a texture. More info
See in Glossary at a low level of detail (LOD).
The most common way to generate a Billboard Asset is to create files in SpeedTree Modeler, and then import them into Unity.
It is also possible to create your own Billboard Assets from script. For more information, see the API reference for BillboardAsset.