Alternatively, you can create your own Trees. To help prototyping, Unity provides several sample SpeedTree Tree GameObjects in the Standard Assets package. From here, you can select a Tree asset from your Project and add it as a Tree Prefab for use with the brush: The Add Tree window Click the Edit Trees button and select Add Tree. In order to start painting onto the Terrain, you need to add a Tree. Initially, the Terrain will have no Trees available. The Tree button on the toolbar enables Tree painting: This means that you can have dense forests with thousands of trees and still keep an acceptable frame rate. Unity uses optimisations, like billboarding for distant Trees, to maintain good rendering performance. However, Trees are solid 3D GameObjects that grow from the surface. To enhance Unity Terrains, you can paint Trees onto a Terrain in much the same way as painting height maps and textures.