Estimating Sensor Motion from Wide-Field Optical Flow on a Log-Dipolar Sensor

Log-polar image architectures, motivated by the structure of the human visual field, have long been investigated in computer vision for use in estimating motion parameters from an optical flow vector field. Practical problems with this approach have been: (i) dependence on assumed alignment of the visual and motion axes; (ii) sensitivity to occlusion form moving and stationary objects in the central visual field, where much of the numerical sensitivity is concentrated; and (iii) inaccuracy of the log-polar architecture (which is an approximation to the central 20°) for wide-field biological vision. In the present paper, we show that an algorithm based on generalization of the log-polar architecture; termed the log-dipolar sensor, provides a large improvement in performance relative to the usual log-polar sampling. Specifically, our algorithm: (i) is tolerant of large misalignmnet of the optical and motion axes; (ii) is insensitive to significant occlusion by objects of unknown motion; and (iii) represents a more correct analogy to the wide-field structure of human vision. Using the Helmholtz-Hodge decomposition to estimate the optical flow vector field on a log-dipolar sensor, we demonstrate these advantages, using synthetic optical flow maps as well as natural image sequences

Exact Geosedics and Shortest Paths on Polyhedral Surface

We present two algorithms for computing distances along a non-convex polyhedral surface. The first algorithm computes exact minimal-geodesic distances and the second algorithm combines these distances to compute exact shortest-path distances along the surface. Both algorithms have been extended to compute the exact minimalgeodesic paths and shortest paths. These algorithms have been implemented and validated on surfaces for which the correct solutions are known, in order to verify the accuracy and to measure the run-time performance, which is cubic or less for each algorithm. The exact-distance computations carried out by these algorithms are feasible for large-scale surfaces containing tens of thousands of vertices, and are a necessary component of near-isometric surface flattening methods that accurately transform curved manifolds into flat representations.National Institute for Biomedical Imaging and Bioengineering (R01 EB001550

Being and Becoming: Learning, Skill, and Cognition as Exhibited on Painted White Ware Pottery at Sand Canyon Pueblo (5MT765), a Pueblo III Era Community Center in Southwestern Colorado

The theory of conceptual metaphor through material culture posits that human physical experience with natural and cultural materials serves as the basis for the development of abstract knowledge (Tilley 1999). Apprenticeship theories in archaeology (e.g. Walleart ed. 2012) study how craft knowledge is transmitted generationally. Combining these approaches, this thesis seeks to understand if the “container metaphor” (sensu Ortman 2000a, 2012) was taught by adults and learned by children at the Sand Canyon Pueblo archaeological site in southwest Colorado, by comparing white ware pottery produced by children to those produced by adults. Patricia Crown’s (1999, 2001, 2002) 18-point attribute analysis for determining the age and skill level of producers of painted designs of pre-Hispanic southwestern ceramics was adapted and tested on those vessels. The results of the study show that most ladles and several other vessels exhibit multiple less-skilled techniques that strongly suggest childhood production. It is determined that the attribute analysis can be usefully employed to assess a range of skills not necessarily related to youth production, as it is demonstrated more broadly that relative levels of exhibited skill in painting are tied to specific vessel forms. It is shown that circles are near universally communicated as a design motif on pottery containers by all members of the Sand Canyon community of practice, regardless of age or skill. It is suggested that CIRCLES ARE CONTAINERS was a metaphor learned and experienced during childhood. Possible metaphorical links between ladles and childhood are considered. However, more research is needed to develop these ideas further

Catering for Israeli-Palestinian Peace

In retrospect, that September day in 1993 was filled with irony. The United States has often been accused of serving merely as a caterer for peace. By this, I suppose, is meant passively hosting ceremonial signings rather than exercising superpower responsibilities. (The U.S. has also, of course, been accused of the opposite-dictating solutions to life-and-death issues whose consequences Americans will not have to bear.) All I knew at the time was that the Israeli and Palestinian legal representatives were not agreed on the final wording of their document, and I was not going to allow the dispute to move on to the stage to the embarrassment of all concerned. This initial experience taught me there can be far more to catering for peace than meets the eye. Simply providing technical assistance in preparing documents or logistical support for negotiations can be tricky, even nerve-wracking. But third-party facilitators can play an invaluable role in defusing the emotional barriers that impede constructive problem-solving for more than ceremonial events. For the United States, this has meant careful attention to nurturing the negotiating environment for Palestinian-Israeli peace talks. The U.S. has used its influence to urge the parties to restrain their public rhetoric and encouraged them to engage in confidence-building measures. More generally, it has expressed unwavering support for the process and sought to instill a sense of optimism to help build constituent support. When, as has happened all too often, the enemies of peace have lashed out violently, the United States has used its influence and prestige to overcome shocks to the process. It has organized and hosted emergency summits, boosted its own counter-terrorism support, and given the parties the confidence to continue once they have buried their dead. [CONT