Generalized Chain Codes Research Articles

Visual Feedback for a Robert to Recogninz and Pick up Parts

A robot workstation is described, which uses visual feedback to complete its assembly task. A camera is mounted on the robot tool. The system will recognize the part needed and follow it as it moves on a conveyor belt. It is grasped when position and speed information has stabilized. In order to achieve the high communication rates necessary for visual servoing, all information is processed with the PUMA real-time path control facility. The vision algorithms are implemented on the ICOS 20000 Vision Computer. They are based on multi-resolution curvature measures for the object contours. These contours are encoded with the "reduced generalized chain code". The vision system includes an automated object modelling facility which is demonstrated by some examples. Also the preliminary scheme of a strategic planner module is described. This program tries to optimally guide the recognition program in order to minimize calculation time.

A rate and distortion analysis of chain codes for line drawings

The performance of chain codes for line drawings in the framework of source coding with a fidelity criterion is investigated. A formal characterization is given for a broad class of chain codes that includes the generalized chain codes of Freeman and the convex quantizers of Koplowitz. Measures of distortion (fidelity) and rate (efficiency) are introduced. The distortion and rate are calculated for several types of chain codes applied to straight and slowly curving lines. Several statistical models for straight lines are introduced and the average performance of chain codes for these models is investigated.

Analysis of the Precision of Generalized Chain Codes for the Representation of Planar Curves

This paper examines a set of line-segment approximation codes for the representation of planar curves (the so-called generalized chain codes) and shows that the average quantization error (measure of code's precision) is directly proportional to the grid size and is independent of the form of the code. Thus, to achieve a desired level of precision for the representation of a line drawing, only the size of the grid need be determined; the form of the code can be chosen on the basis of other criteria, such as compactness, smoothness, or relative ease of encoding and processing.