Encoded moire inspection based on a computer solid model

An investigation into a system linking a computer solid modeler to an active stereo imaging inspection station is presented. Given the computer solid model of a surface, a projected pattern can be encoded so that the reflections from the object's surface exhibit a uniformly simple pattern when the object's surface and the modeled surface are identical. Research concerning the method of generating projection patterns, as well as the sensitivity of the system, is discussed. A prototype system consisting of a computer graphics workstation; a flexible projector, and a machine vision system was used to inspect two different manufactured parts     

On segmenting the three-dimensional scan data of a human body

Software for categorizing a cloud of more than 300,000 three-dimensional (3-D) surface data points, captured from a human subject, is presented. The software is part of an incremental approach that progressively refines the identification of human anthropometric landmarks. The first phase of identification is to orient and segment the human body data points. A step-by-step method for these tasks is presented. One of the algorithms, a discrete point cusp detector, plays a fundamental role in separating the data cloud. The theory and operation of the algorithm is explained. The discrete cusp detector can be used to separate any two cylindrical objects, in (3-D) data, whose boundaries touch. The software has been tested on over a hundred different body scan data sets and shown to be robust.     

Smoothing random noise from human head scan data

In obtaining human head range data with a laser scanner, noise results from system errors and rough surfaces. The noise can be reduced with a suitable filter. Two aspects need to be considered in smoothing head scan data: one is finding a filter to eliminate noise without creating new artifacts; the other is determining the parameters of this filter to achieve optimal smoothing. The Gaussian filter has been shown to have unique characteristics which preserve the integrity of the data. A cross-validation method based on regularization theory has been derived for estimating the correct filter size for smoothing head range data. The authors discuss the justification and implementation of the statements above. Generalized cross-validation is derived in the two-dimensional case. Experimental results are presented that show the technique is effective and robust.     

Positioning quadric surfaces in all active stereo imaging system

The location of surfaces using stereo imaging techniques is an important area of research for robot guidance and machine inspection applications, The underlying geometry of finite focal length stereo pinhole cameras is investigated. This is the model used in both active and passive stereo imaging systems. It is shown that the points of intersecting views from the pinhole models result in conic sections. This information is used to locate quadric surfaces in the inspection space. When the projected fringe pattern is encoded to a quadric surface, the underlying intersection mapping can be used to estimate the position of the surface. Subsets of most smooth objects can be fitted to a conic section. For inspection of smooth surfaces with projection moire techniques, this fringe interpretation method would allow for correct placement of the object