Error behavior
•Hough handles error with buckets.  This gives a larger set of lines consistent with point, but ad-hoc.
•Ransac handles error with threshold.  Well-motivated for error in other points, but not for error in first 2 points.
–But works if we find some 2 points w/ low error.
•Error handling sloppy -> clutter bigger problem.
•Many variations to handle these issues.
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