Version: 2019.4

TerrainData.enableHolesTextureCompression

マニュアルに切り替える
public bool enableHolesTextureCompression ;

説明

Enable the Terrain holes Texture compression.

Set to true to compress the Terrain holes Texture. This property takes effect only at runtime, and is true by default. Terrain holes Textures are never compressed in the Editor. See TerrainData.holesTexture for details.