Analysis of three-dimensional motions in blocks world

摘要

This paper describes a computational analysis of three-dimensional motion in the blocks world. Input is a sequence of line drawings of rigid trihedral blocks projected orthogonally on an image plane. The blocks can show complex coincidental motion such that a block rotates around a joint attached to one side of another moving block.At first, a labeling scheme and an object-to-object matching method are applied to the image sequence to segment the images into individual blocks and find correspondences of their vertices between frames. A transition table of junction labels and contextual information between frames are used to analyze structural changes of the line drawings. Next, the shape rigidness property of three vertices on a block is used to evaluate geometrical parameters, such as orientations and edge lengths, then their interframe rotational movements are determined.Thus, the dynamic line images are interpreted as three-dimensional motion of blocks.