New Releases by Paul Horn

This is a primer on extended Gaussian Images. Extended Gaussian Images are useful for representing the shapes of surfaces. They can be computed easily from: (1) Needle maps obtained using photometric stereo, or (2) Depth maps generated by ranging devices or stereo. Importantly, they can also be determined simply from geometric models of the objects. Extended Gaussian images can be of use in at least two of the tasks facing a machine vision system: (1) Recognition, and (2) Determining the attitude in space of an object. Here, the extended Gaussian image is defined and some of its properties discussed. Here, the extended Gaussian image is defined and some of its properties discussed. An elaboration of non-convex objects is presented and several examples are shown. (Author).

One of the remaining obstacles to the widespread application of industrial robots is their inability to deal with parts that are not precisely positioned. In the case of manual assembly, components are often presented in bins. Current automated systems, on the other hand, require separate feeders which present the parts with carefully controlled position and attitude. Here we show how results in machine vision provide techniques for automatically directing a mechanical manipulator to pick one object at a time out of a pile. The attitude of the object to be picked up is determined using a histogram of the orientations of visible surface patches. Surface orientation, in turn, is determined using photometric stereo applied to multiple images. These images are taken with the same camera but differing lighting. The resulting needle map, giving the orientations of surface patches, is used to create an orientation histogram which is a discrete approximation to the extended Gaussian image. This can be matched against a synthetic orientation histogram obtained from prototypical models of the objects to be manipulated. Such models may be obtained from computer aided design (CAD) databases. The method thus requires that the shape of the objects be described, but it is not restricted to particular types of objects. (Author).

Frequency response and transfer functions. Sensitivity and figure-of-merit. Building blocks for cascade filter design. Design equations and flow charts. Tuning active filters. Designing nth-order active filters. Practical hints for active filter design. Appendix: Program records for the SR-59 pocket calculator. FORTRAN program listing for a PDP-11 computer. BASIC program listing for the TRS-80 minicomputer. Testing the programs numerically.