Collision detections between scene geometry -
The SoIntersectionDetectionAction class is for detecting
intersecting primitives in a scene.
Note that only collisions between actual geometry in the scene is
detected, so the contents of some special nodes like e.g. SoText2 and
SoImage (which projects to screen-plane bitmap graphics, and not actual
polygons) will not be considered for collision detection. "
Version 2.5.0 Collision2detections between scene geometry(3)