Level of detail (LOD) allows an overall world become very large by letting an author provide
high-fidelity models when a viewer is nearby, and simpler geometry when the viewer is far away.
The further the viewer can see, the more there is to draw.
Note that if a shape is distant, the shape is smaller and the viewer can't see as much detail.
So... draw it with less detail.
Varying detail with distance reduces initial download time and increases drawing speed.
Increase performance by making multiple levels of shapes: high detail for close up viewing,
progressively lower detail for more distant viewing.
Group the levels in an LOD node, ordered from high detail to low detail, and using an array of range values to select switching distances .
These X3D scenes are adapted directly from the
original VRML 2.0 Sourcebook chapter examples.
VRML 2.0 Sourcebook course notes.