Machine vision system for object feature analysis and validation based on multiple object images

A machine vision method for detecting features of an object in a selected feature plane of the object, the method comprising:

• acquiring a sequence of images of the object, each image in the sequence corresponding to a distinct orientation of the object about a selected object axis;
• inspecting images in the image sequence for feature points of the selected feature plane, as projected into the images, at a number, n, of feature detection locations, by:
• applying an edge detection region at each of the n feature detection locations,
• searching each edge detection region for an edge of an object feature point;
• and
• correlating positions of detected edges to object feature point positions,
• the feature detection locations configured with respect to each other at image positions based on an expected shift in image location of a given feature point between two consecutive images in the image sequence;
• associating detected feature points with an orthogonal-view representation of the selected feature plane;
• and
• identifying as valid object feature points those feature points detected in a specified minimum number of the n feature detection locations each in a different image of the image sequence.

A machine vision method for detecting features of a semiconductor melt surface from which a semiconductor crystal ingot is pulled as the ingot and melt are rotated about a vertical axis of rotation, the method comprising:

• acquiring a sequence of perspective-view images of the melt surface from a fixed viewing location, each image in the sequence corresponding to a perspective view of a distinct orientation of the melt about the vertical axis of rotation;
• inspecting images in the image sequence for melt surface feature points, as projected into the images, at a number, n, of feature detection locations, the feature detection locations configured with respect to each other at image positions based on an expected shift in image location of a given melt surface feature point between two consecutive images in the image sequence;
• mapping detected melt surface feature points from a perspective-view image projection to an orthogonal-view projection of the melt surface;
• and
• identifying as valid melt surface feature points, comprising contour points of solid-phase crystal regions on the surface of the melt, those feature points detected in a specified minimum number of the n feature detection locations each in a different image of the image sequence.