Image Warping Among Arbitrary Planar Shapes

Image warping refers to the 2D resampling of a source image onto a target image. Despite the variety of techniques proposed, a large class of image warping problems remains inadequately solved: mapping between two images which are delimited by arbitrary, closed, planar curves, e.g., hand-drawn curves. This paper describes a novel algorithm to perform image warping among arbitrary planar shapes whose boundary correspondences are known. A generalized polar coordinate parameterization is introduced to facilitate an efficient mapping procedure. Images are treated as collections of interior layers, extracted via a thinning process. Mapping these layers between the source and target images generates the 2D resampling grid that defines the warping. The thinning operation extends the standard polar coordinate representation to deal with arbitrary shapes

A Syntactic Omni-Font Character Recognition System

The author introduces a syntactic omni-font character recognition system that recognizes a wide range of fonts, including handprinted characters. A structural pattern-matching approach is used. Essentially, a set of loosely constrained rules specify pattern components and their interrelationships. The robustness of the system is derived from the orthogonal set of pattern descriptors, location functions, and the manner in which they are combined to exploit the topological structure of characters. By virtue of the new pattern description language, PDL, the user may easily write rules to define new patterns for the system to recognize. The system also features scale-invariance and user-definable sensitivity to tilt orientation. The system has achieved a 95. 2% recognition rate

Cubic Spline Interpolation: A Review

The purpose of this paper is to review the fundamentals of interpolating cubic splines. We begin by defining a cubic spline in Section 1. Since we are dealing with interpolating splines, constraints are imposed to guarantee that the spline actually passes through the given data points. These constraints are described in Section 2. They establish a relationship between the known data points and the unknown coefficients used to completely specify the spline. Due to extra degrees of freedom, the coefficients may be solved in terms of the first or second derivatives. Both derivations are given in Section 3. Once the coefficients are expressed in terms of either the first or second derivatives, these unknown derivatives must be determined. Their solution, using one of several end conditions, is given in Section 4. Finally source code, written in C, is provided in Section 5 to implement cubic spline interpolation for uniformly and nonuniformly spaced data points

Fast Fourier Transforms: A Review

The purpose of this paper is to provide a detailed review of the Fast Fourier Transform. Some familiarity with the basic concepts of the Fourier Transform is assumed. The review begins with a definition of the discrete Fourier Transform (DFT) in section 1. Directly evaluating the DFT is demonstrated there to be an 0 (N2) process. The efficient approach for evaluating the OFT is through the use of FFT algorithms. Their existence became generally known in the mid-1960s, stemming from the work of J. W. Cooley and J. W. Tukey. Although they pioneered new FFT algorithms, the original work was actually discovered over 20 years earlier by Danielson and Lanczos. Their formulation, known as the Danielson-Lanczos Lemma, is derived in section 2. Their recursive solution is shown to reduce the computational complexity to 0 (N log2 N). A modification of that method, the Cooley-Tukey algorithm, is given in section 3. Yet another variation, the Cooley-Sande algorithm, is described in section 4. These last two techniques are also known in the literature as the decimation-in-time and decimation-in-frequency algorithms. respectively. Finally, source code, written in C, is provided in the appendix

Voyages : cultures en évolution

Dans quelles mesures les voyages, par la découverte de l'Autre, ont-ils des conséquences sur notre propre culture ? Voyager dans un certain contexte a beaucoup de répercussions sur la construction de soi et permet de définir notre propre identité. Je souhaite parler de ce que sont pour moi les effets des échanges avec autrui, et ce que m'ont apporté mes voyages dans 26 pays différents. J'ai tenté à chaque fois d'être immergée dans la population locale, en partant à la rencontre volontairement de personnes d'autres cultures (quelles qu'elles soient, tant qu'elles furent différentes de la mienne), ou en vivant quelques mois sur place, pour y travailler ou par simple désir de découverte, lors de ces 8 dernières années. Je prends à chaque fois plaisir à séjourner un certain temps dans ces endroits d'ailleurs, et à rentrer en contact avec les personnes qui y vivent ou qui y passent, en m'immisçant un moment plus ou moins long dans leur quotidien, rythmé par leurs rythmes de vie et leurs points de vue. J'eus tort de penser que d'aller dans les endroits les plus "traditionnels" et les moins touchés par la mondialisation seraient les plus riches. Chaque région est finalement authentique à sa façon, qu'elle soit à caractère traditionnel ou bien pluriculturelle. Aujourd'hui, il est difficile d'aller dans des endroits dans lesquels les peuples vivent encore de façon traditionnelle, tant les divers moyens d'échanges sont nombreux et rapides. Ainsi, il faut arriver à saisir l'identité de chaque peuple, avec ses traditions et ses acculturations. La confrontation avec autrui soulève en nous une multitude de questions, nous écarte peu à peu du modèle social qui accompagne notre culture, redéfinissant notre culture elle-même

Book reviews

Click on the link to view the reviews

Did Arroyo Formation Impact the Occupation of Snake Rock Village, a Fremont Dryland Agricultural Community in Central Utah, ca. AD 1000–1200?

Fremont farmers of the northern Colorado Plateau grew maize at the limits for cultivation in western North America between AD 300–1300. Like other Indigenous farmers throughout the American Southwest, Fremont farmers used bundled agricultural niches where alluvial floodplains were the largest available site for cultivation. But dryland floodplains are a risk to the persistence of farming communities because the development of steep-sided arroyos lowers floodplain surfaces and water tables, rendering them unusable for growing maize. This study tests the relationship between the occupational timing of Snake Rock Village between AD 970–1240 and the formation of a 4.5m deep arroyo on Ivie Creek adjacent to the site. I present a high-precision AMS radiocarbon chronology of the village occupation paired with an AMS radiocarbon reconstruction of the Ivie Creek floodplain 400m upstream from the site. The results of this study provide a direct test of arroyo formation as a cause for the abandonment of Fremont agriculture by AD 1300. The results indicated that the abandonment of Snake Rock Village does not correspond with an incision of the adjacent floodplain. Instead, the floodplain was still aggrading when Snake Rock Village was abandoned, and the incision did not happen until AD 1570 or AD 1725. Thus, while some evidence implicates arroyo formation as one factor contributing to the abandonment of early agricultural villages in other parts of the northern Colorado Plateau, arroyo formation did not appear to constrain the persistence of floodplain farming on Ivie Creek

An Evolving Main Street: The Impact of Urban Renewal on Downtown Las Cruces, New Mexico, 1966-1974

This thesis explores how the process of urban renewal affected the City of Las Cruces, its population, and its urban landscape between 1966 and 1974. It tells the story of municipal planning in Las Cruces, New Mexico, a small southwestern city, following the Second World War. This thesis tries to answer the question of why officials favored the application of suburban planning solutions to the downtown. What reasoning lead to the adoption and construction of the ill-fated pedestrian mall in Las Cruces? Finally, this analysis assesses urban renewals results and its true costs in Las Cruces, some of which can be measured in public opinion and in loss of regional culture and history to rational planning and its all-too frequent partners, the wrecking ball and bulldozer. City leaders encouraged low-density development through annexations and approval of subdivision and commercial strip construction, to the detriment of an ailing downtown. Las Cruces officials embraced suburban trends and transformed downtown into an outdoor-covered shopping center. With the demolition of hundreds of structures, municipal leaders replaced Main Street\u27s rich, regional history with expansive parking lots and an unsuccessful pedestrian mall that mimicked enclosed shopping centers