Ames vision group research overview

A major goal of the reseach group is to develop mathematical and computational models of early human vision. These models are valuable in the prediction of human performance, in the design of visual coding schemes and displays, and in robotic vision. To date researchers have models of retinal sampling, spatial processing in visual cortex, contrast sensitivity, and motion processing. Based on their models of early human vision, researchers developed several schemes for efficient coding and compression of monochrome and color images. These are pyramid schemes that decompose the image into features that vary in location, size, orientation, and phase. To determine the perceptual fidelity of these codes, researchers developed novel human testing methods that have received considerable attention in the research community. Researchers constructed models of human visual motion processing based on physiological and psychophysical data, and have tested these models through simulation and human experiments. They also explored the application of these biological algorithms to applications in automated guidance of rotorcraft and autonomous landing of spacecraft. Researchers developed networks for inhomogeneous image sampling, for pyramid coding of images, for automatic geometrical correction of disordered samples, and for removal of motion artifacts from unstable cameras

Image management research

Two types of research issues are involved in image management systems with space station applications: image processing research and image perception research. The image processing issues are the traditional ones of digitizing, coding, compressing, storing, analyzing, and displaying, but with a new emphasis on the constraints imposed by the human perceiver. Two image coding algorithms have been developed that may increase the efficiency of image management systems (IMS). Image perception research involves a study of the theoretical and practical aspects of visual perception of electronically displayed images. Issues include how rapidly a user can search through a library of images, how to make this search more efficient, and how to present images in terms of resolution and split screens. Other issues include optimal interface to an IMS and how to code images in a way that is optimal for the human perceiver. A test-bed within which such issues can be addressed has been designed

Pyramid image codes

All vision systems, both human and machine, transform the spatial image into a coded representation. Particular codes may be optimized for efficiency or to extract useful image features. Researchers explored image codes based on primary visual cortex in man and other primates. Understanding these codes will advance the art in image coding, autonomous vision, and computational human factors. In cortex, imagery is coded by features that vary in size, orientation, and position. Researchers have devised a mathematical model of this transformation, called the Hexagonal oriented Orthogonal quadrature Pyramid (HOP). In a pyramid code, features are segregated by size into layers, with fewer features in the layers devoted to large features. Pyramid schemes provide scale invariance, and are useful for coarse-to-fine searching and for progressive transmission of images. The HOP Pyramid is novel in three respects: (1) it uses a hexagonal pixel lattice, (2) it uses oriented features, and (3) it accurately models most of the prominent aspects of primary visual cortex. The transform uses seven basic features (kernels), which may be regarded as three oriented edges, three oriented bars, and one non-oriented blob. Application of these kernels to non-overlapping seven-pixel neighborhoods yields six oriented, high-pass pyramid layers, and one low-pass (blob) layer

Habitable Zone Lifetime of Exoplanets around Main Sequence Stars

Funding: Dean's Scholarship at the University of East Anglia.The potential habitability of newly discovered exoplanets is initially assessed by determining whether their orbits fall within the circumstellar habitable zone of their star. However, the habitable zone (HZ) is not static in time or space, and its boundaries migrate outward at a rate proportional to the increase in luminosity of a star undergoing stellar evolution, possibly including or excluding planets over the course of the star’s main sequence lifetime. We describe the time that a planet spends within the HZ as its ‘‘habitable zone lifetime.’’ The HZ lifetime of a planet has strong astrobiological implications and is especially important when considering the evolution of complex life, which is likely to require a longer residence time within the HZ. Here, we present results from a simple model built to investigate the evolution of the ‘‘classic’’ HZ over time, while also providing estimates for the evolution of stellar luminosity over time in order to develop a ‘‘hybrid’’ HZ model. These models return estimates for the HZ lifetimes of Earth and 7 confirmed HZ exoplanets and 27 unconfirmed Kepler candidates. The HZ lifetime for Earth ranges between 6.29 and 7.79 · 109 years (Gyr). The 7 exoplanets fall in a range between ∼1 and 54.72 Gyr, while the 27 Kepler candidate planets’ HZ lifetimes range between 0.43 and 18.8 Gyr. Our results show that exoplanet HD 85512b is no longer within the HZ, assuming it has an Earth analog atmosphere. The HZ lifetime should be considered in future models of planetary habitability as setting an upper limit on the lifetime of any potential exoplanetary biosphere, and also for identifying planets of high astrobiological potential for continued observational or modeling campaigns.Publisher PDFPeer reviewe

Vision Science and Technology at NASA: Results of a Workshop

A broad review is given of vision science and technology within NASA. The subject is defined and its applications in both NASA and the nation at large are noted. A survey of current NASA efforts is given, noting strengths and weaknesses of the NASA program

The Silent Revolution in Methods of Advocacy in English Courts

George Keeton wrote, in 1943, about “a silent revolution in methods of advocacy as practiced by the English Bar over the last fifty years” . Changed standards of etiquette, professional rules and greater control exerted by judges over these years led to a vast increase in courtesy in interactions with judges and between counsel. The conduct of prosecutions had also improved. They were generally no longer carried out in a sneering hectoring manner with witnesses mercilessly browbeaten or bullied. Dramatic types of 19th Century advocacy, in which counsel was prepared to use mannerisms, tricks of speech and gestures to heighten the effects of their pleas to juries, was replaced by a conversational and matter of fact tone. The idea that to cross-examine meant to examine crossly had almost vanished. Appeals to juries were now to reason combined with a controlled, subtle and focused appeal to emotion. Jury trials in civil cases had continued to decline. Advocacy before judges was concerned with facts and the law, not oratorical flourishes. Fewer criminal trials before juries took place as the jurisdiction of the magistrates had widened further. The more restrained and conversational style of advocacy before criminal juries may have been to some extent influenced by that of the civil courts, where the leaders of the bar appeared more often and increasingly without juries. Two dominant members of the bar during the first half of the 20th Century were Patrick Hastings and Norman Birkett. Their styles, because of triumphs linked with them, were influential on those of other barristers. Hastings was a master of direct forcible speech without any embellishments or ornamentation and prized brevity. Unlike Hastings, Norman Birkett believed that the advocate ought to use the full range of English speech. Other factors lay behind the mainly conversational and matter of fact advocacy that had become established. These include a widely held suspicion of rhetoric and, very importantly, better informed and greater educated juries. Jurors were less susceptible than their predecessors to theatrical gestures and melodrama, which had largely been replaced in literature and on the stage by introspection and realism, references to God and the Bible, elegant and flowery, but empty, speech and appeals to strong emotion and prejudice. In a more scientific age jurors expected more of an appeal to reason. The success of barristers such as Hardinge Giffard, John Holker, Charles Russell and Edward Clarke, during the closing decades of the previous century, may have been because they appreciated early on the changes that were occurring to juries. Attempting to catch the eye of the press to help create a reputation, useful to generate work, was an important factor behind the emotive, vividly worded and aggressive advocacy of the early Victorian period and afterwards. The later decline of court reporting in the newspapers, removing much of the gallery from the stage, may well have contributed to the more subdued form of speech