Caractérisation de la projection du squelette d'une surface canal 3D : Application à la reconstruction 3D à partir de deux images

International audienceNous présentons dans cet article une nouvelle approche pour reconstruire un objet 3D à partir de deux images de celui-ci. L'originalité de notre approche vient du fait que nous n'estimons pas directement la surface de l'objet 3D mais son squelette. Ce travail s'appuie sur les deux contributions suivantes. Premièrement, nous décrivons la relation existant entre un squelette 3D et sa projection, orthographique ou perspective, sur un plan image. Ensuite, nous montrons comment retrouver le squelette 3D à partir de deux de ses projections. Contrairement aux méthodes de reconstruction 3D classiques qui génèrent un nuage de points sans maillage, cette approche a pour avantage de reconstruire aussi la topologie de l'objet, c'est-à-dire d'en retrouver un maillage sans traitement annexe. Nous traitons ici des objets représentables par un squelette 3D curviligne et nous supposons aussi que les points de vue sont calibrés

Structural Extremes in a Cretaceous Dinosaur

Fossils of the Early Cretaceous dinosaur, Nigersaurus taqueti, document for the first time the cranial anatomy of a rebbachisaurid sauropod. Its extreme adaptations for herbivory at ground-level challenge current hypotheses regarding feeding function and feeding strategy among diplodocoids, the larger clade of sauropods that includes Nigersaurus. We used high resolution computed tomography, stereolithography, and standard molding and casting techniques to reassemble the extremely fragile skull. Computed tomography also allowed us to render the first endocast for a sauropod preserving portions of the olfactory bulbs, cerebrum and inner ear, the latter permitting us to establish habitual head posture. To elucidate evidence of tooth wear and tooth replacement rate, we used photographic-casting techniques and crown thin sections, respectively. To reconstruct its 9-meter postcranial skeleton, we combined and size-adjusted multiple partial skeletons. Finally, we used maximum parsimony algorithms on character data to obtain the best estimate of phylogenetic relationships among diplodocoid sauropods. Nigersaurus taqueti shows extreme adaptations for a dinosaurian herbivore including a skull of extremely light construction, tooth batteries located at the distal end of the jaws, tooth replacement as fast as one per month, an expanded muzzle that faces directly toward the ground, and hollow presacral vertebral centra with more air sac space than bone by volume. A cranial endocast provides the first reasonably complete view of a sauropod brain including its small olfactory bulbs and cerebrum. Skeletal and dental evidence suggests that Nigersaurus was a ground-level herbivore that gathered and sliced relatively soft vegetation, the culmination of a low-browsing feeding strategy first established among diplodocoids during the Jurassic

Ecosystem Shock: The Devastating Impacts of Invasive Species on the Great Lakes Food Web

Gives an account of the changes to the Great Lakes ecosystem brought about by non-native aquatic species. Assesses the current and future impacts on fish communities and commercial fisheries. Provides policy and research recommendations

Characterization of Surface Water Quality along Ismailia Canal, Nile River, Egypt

Ismailia Canal, one of the main branches of the Nile River in Egypt, is considered as one of the most important irrigation and drinking water source for Ismailia, Port Said and Suez governorates. The canal received industrial, municipal and agricultural wastewater which caused deterioration in its water quality. To determine the spatial variability of Ismailia canal water quality and identify the sources of pollution that presently affect the canal water quality, the scope of study was divided into three main parts. In the first part, the assessment of water quality data was monitored at thirty different sampling station along the canal, over the period of two years (2017, 2018), using 30 physicochemical and biological water quality variables and using multivariate statistics of principal components analysis (PCA) to interpret before the step of analyzing the concealed variables that determined the variance of observed water quality of various source points was conducted. In the second part, the major dominant factors responsible for canal water quality variations was driven. In the third part, K-means algorithm was used for cluster characterization analysis.The result of PCA shows that 8 principal components contained the key variables and accounted for 87.34% of total variance of the canal water quality and the dominant water quality parameters were: Lead (Pb), Total Phosphorus (TP), Ammonia (NH3), Turbidity, Fecal Coliform (FC), Iron (Fe) and Aluminum (AL). However, the results from K-Means Algorithm for clustering analysis were based on the dominant parameters concentrations, determined 5 cluster groups and produced cluster centers (prototypes). Referring to the clustering classification, a noted water quality was deteriorating as the cluster number increased from 1 to 5, thus the cluster grouping could be used to identify the physical, chemical and biological processes creating the variations in the canal water quality parameters.This study provides an insight into the various statistical models, when water quality monitoring data are combined with spatial data for characterizing spatial and temporal trends, indicating their important potential for decreasing the costs associated with monitoring. This can also be very useful to international water resource authorities for the control and management of pollution and better protection of surface water quality

EXISTING WITHOUT PERMISSION: A VISUAL RHETORICAL ANALYSIS ON BANKSY’S NOLA CHILDREN AND THE BETRAYAL OF AUTHORITY

This study examines eight images by the world renowned—and incognito—graffiti street artist known only as Banksy. The eight images are all of lone children; fourteen paintings comprise the total of Banksy’s 2008 visit to post-Katrina New Orleans. For the research, the eight images of children are referred to collectively as the “NOLA Children Series.” Banksy critics and fans have provided their own names for each piece: Simpsons Boy, Umbrella Girl, Fridge Kite, Levee Boy, Life Preserver Swing, Girl on Stool, and Trumpet Boy 1 & 2. The primary research objective was to understand Banksy’s motives for creating these eight “dramas” as he did. Secondarily, the research also advances the interpretative framework for Visual Rhetoric. Close Textual Analysis and Kenneth Burke\u27s Dramatistic Pentad combine as methods informed by scholarship in visual design and visual rhetoric. The study concludes by noting Banksy’s condemnation of authority figures for their role in betraying the children of New Orleans. Recent studies confirm that the failed levees and failed leadership of 2005 still haunt those who were children when Hurricane Katrina made landfall in Southeast Louisiana

Squelettes pour la reconstruction 3D : de l'estimation de la projection du squelette dans une image 2D à la triangulation du squelette en 3D

La reconstruction 3D consiste à acquérir des images d’un objet, et à s’en servir pour en estimer un modèle 3D. Dans ce manuscrit, nous développons une méthode de reconstruction basée sur la modélisation par squelette. Cette méthode a l’avantage de renvoyer un modèle 3D qui est un objet virtuel complet (i.e. fermé) et aisément éditable, grâce à la structure du squelette. Enfin, l’objet acquis n’a pas besoin d’être texturé, et entre 3 et 5 images sont suffisantes pour la reconstruction. Dans une première partie, nous étudions les aspects 2D de l’étude. En effet, l’estimation d’un squelette 3D nécessite d’étudier la formation de la silhouette de l’objet à partir de son squelette, et donc les propriétés de sa projection perspective, appelée squelette perspectif. Cette étude est suivie par notre première contribution : un algorithme d’estimation de la projection perspective d’un squelette 3D curviligne, constitué d’un ensemble de courbes. Cet algorithme a toutefois tendance, comme beaucoup d’algorithmes estimant un squelette, à générer des branches peu informatives, notamment sur une image rastérisée. Notre seconde contribution est donc un algorithme d’estimation de squelette 2D, capable de prendre en compte la discrétisation du contour de la forme 2D, et d’éviter ces branches peu informatives. Cet algorithme, d’abord conçu pour estimer un squelette classique, est ensuite généralisé à l’estimation d’un squelette perspectif. Dans une seconde partie, nous estimons le squelette 3D d’un objet à partir de ses projections. Tout d’abord, nous supposons que le squelette de l’objet 3D à reconstruire est curviligne. Ainsi, chaque squelette perspectif estimé correspond à la projection du squelette 3D de l’objet, sous différents points de vue. La topologie du squelette étant affectée par la projection, nous proposons notre troisième contribution, l’estimation de la topologie du squelette 3D à partir de l’ensemble de ses projections. Une fois celle-ci estimée, la projection d’une branche 3D du squelette est identifiée sur chaque image, i.e. sur chacun des squelettes perspectifs. Avec cette identification, nous pouvons trianguler les branches du squelette 3D, ce qui constitue notre quatrième contribution : nous sommes donc en mesure d’estimer un squelette curviligne associé à un ensemble d’images d’un objet. Toutefois, les squelettes 3D ne sont pas tous constitués d’un ensemble de courbes : certains d’entre eux possèdent aussi des parties surfaciques. Notre dernière contribution, pour reconstruire des squelettes 3D surfaciques, est une nouvelle approche pour l’estimation d’un squelette 3D à partir d’images : son principe est de faire grandir le squelette 3D, sous les contraintes données par les images de l’objet

Untitled Context- part 2

The original is an emblem of industrialization. It is the homogeneous and the rule. Through methods of reproduction and reduction, the object creates a new identity, invigorating pre-existing conditions. This research explores the resolution of the replica through the reproduced and the reduced. The reproduced uses the syntax of the original as a framework to produce an object containing the same components, but altered and modifies to the new context. Many towers built around the worlds that reference the Eiffel Tower as an influence, contain components of the tower that have altered and modified to the new context. These tests formulate architectural conditions within the series allowing a deeper understanding of the object. The reduced uses the symbols of the original as a framework to capture the object in a timeless medium. This allows for the reduced to mainly focus on the object without true context. The context is altered to the symbolism conveyed by the object