At specified distances from the camera, the terrain quads will be combined to reduce the number of triangles rendered. The terrain system incorporates an optional rendering optimization that uses dynamic LOD tesselation to reduce the number of triangles rendered in the distance. These values are normally modified by painting the terrain mesh in the Unreal Editor or by importing a heightmap file that contains the altitude values for the terrain mesh vertices. For cliff-like slopes, staticmeshes should be used instead of attempting to use a very high density terrain.Įach terrain grid vertex's Z coordinate value can be set to within a 16-bit range (0 to 65535) to specify its relative altitude. The constant X.Y spacing also determines the maximum slope angle that can be created for a given relative altitude between two vertices: the smaller the grid spacing (DrawScale) value, the steeper the available slope. The constant X.Y spacing also means that geographical systems such as caves and overhangs cannot be created directly by the terrain object and must be added as additional mesh objects placed into the scene.

Since the terrain uses a constant X.Y spacing, mesh triangle-count optimization through combining co-planar faces is not supported, so a 128x128 terrain will always have an underlying 129x129 heightmap array. The terrain object in UE3 is a standard 3D planar mesh grid with constant X.Y spacing that is specified by the Display.DrawScale and /.Y properties.

Unreal Engine 3 supports two terrain design techniques, which include hand-painting directly on the terrain mesh to create the hills and valleys, and importing externally created heightmap files in UnrealEd's G16 bitmap or T3D mesh formats.

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