MP

The default terrain engine for osgEarth renders an unlimited number of image layers using a tile-level multipass blending technique.

Example usage:

<map>
    <options>
        <terrain driver                   = "mp"
                 skirt_ratio              = "0.05"
                 color                    = "#ffffffff"
                 normalize_edges          = "false"
                 incremental_update       = "false"
                 quick_release_gl_objects = "true"
                 min_tile_range_factor    = "7.0"
                 cluster_culling          = "true" />

Properties:

skirt_ratio:The “skirt” is a piece of vertical geometry that hides gaps between adjacent tiles with different levels of detail. This property sets the ratio of skirt height to the width of the tile.
color:Color of the underlying terrain (without imagery) in HTML format. Default = “#ffffffff” (opaque white). You can adjust the alpha to get transparency.
normalize_edges:
 Post-process the normal vectors on tile boundaries to smooth them across tiles, making the tile boundaries less visible when not using imagery.
incremental_update:
 When enabled, only visible tiles update when the map model changes (i.e., when layers are added or removed). Non-visible terrain tiles (like those at lower LODs) don’t update until they come into view.
quick_release_gl_objects:
 When true, installs a module that releases GL resources immediately when a tile pages out. This can prevent memory run-up when traversing a paged terrain at high speed. Disabling quick-release may help achieve a more consistent frame rate.

Common Properties:

min_tile_range_factor:
 The “maximum visible distance” ratio for all tiles. The maximum visible distance is computed as tile radius * this value. (default = 7.0)
cluster_culling:
 Cluster culling discards back-facing tiles by default. You can disable it be setting this to false, for example if you want to go underground and look up at the surface.