Machine vision system for analyzing features based on multiple object images

Abstract

Provided is the ability to produce an orthogonal-view representation of a selected feature plane of a three-dimensional object. A plurality of images of the object are acquired, each corresponding to a distinct orientation of the object about a selected object axis. In at least one acquired image, feature points are identified in the selected feature plane as-projected into that acquired image. Feature points are associated with an orthogonal-view representation of the selected feature plane, and feature points from at least one acquired image are correlated with physical orientations on the selected feature plane based on the object orientation corresponding to that acquired image. An orthogonal-view representation of the selected object feature plane can be analyzed for a specified feature configuration even when the acquired object images are perspective-view images. This can be accomplished even through only a subset of feature points may be available in any one given image of the object. Such may be the case, e.g., where portions of a complicated three-dimensional object obscure other portions of the object in a selected view of the object. Also provided is an ability to analyze an orthogonal-view representation of a circumferential object contour, e.g., a meniscus defined on a semiconductor melt surface from which a semiconductor crystal ingot is horizontally pulled to grow the crystal ingot. The invention enables monitoring of the crystal growth for faults occurring during the growth process.