Shape Matching By Part Alignment Using Extended Chordal Axis Transform

International audienceOne of the main challenges in shape matching is overcoming intra–class variation where objects that are conceptually similar have significant geometric dissimilarity. The key to a solution around this problem is incorporating the structure of the object in the shape descriptor which can be described by a connectivity graph customarily extracted from its skeleton. In a slightly different perspective, the structure may also be viewed as the arrangement of protruding parts along its boundary. This arrangement does not only convey the protruding part's ordering along the anti clockwise direction, but also relates these parts on different levels of detail. In this paper, we propose a shape matching method that estimates the distance between two objects by conducting a part-to-part matching analysis between their visual protruding parts. We start by a skeleton-based segmentation of the shape inspired by the Chordal Axis Transform. Then, we extract the segments that represent the protruding parts in its silhouette on varied levels of detail. Each one of these parts is described by a feature vector. A shape is thus described by the feature vectors of its parts in addition to their angular and linear proximities to each other. Using dynamic programming, our algorithm finds a minimal cost correspondence between parts. Our experimental evaluations validate the proposition that part correspondence allows conceptual matching of precisely dissimilar shapes

Identifying Perceptually Salient Features on 2D Shapes

International audienceMaintaining the local style and scale of 2D shape features during deformation, such as when elongating, compressing, or bending a shape, is essential for interactive shape editing. To achieve this, a necessary first step is to develop a robust classification method able to detect salient shape features, if possible in a hierarchical manner. Our aim is to overcome the limitations of existing techniques, which are not always able to detect what a user immediately identifies as a shape feature. Therefore, we first conduct a user study enabling us to learn how shape features are perceived. We then propose and compare several algorithms, all based on the medial axis transform or similar skeletal representations, to identify relevant shape features from this perceptual viewpoint. We discuss the results of each algorithm and compare them with those of the user study, leading to a practical solution for computing hierarchies of salient features on 2D shapes

Sketch-based 3D Object Retrieval Using Two Views and Visual Part Alignment

International audienceHand drawn figures are the imprints of shapes in human's mind. How a human expresses a shape is a consequence of how he or she visualizes it. A query-by-sketch 3D object retrieval application is closely tied to this concept from two aspects. First, describing sketches must involve elements in a figure that matter most to a human. Second, the representative 2D projection of the target 3D objects must be limited to ''the canonical views'' from a human cognition perspective. We advocate for these two rules by presenting a new approach for sketch-based 3D object retrieval that describes a 2D shape by the visual protruding parts of its silhouette. Furthermore, the proposed approach computes estimations of ''part occlusion'' and ''symmetry'' in 2D shapes in a new paradigm for viewpoint selection that represents 3D objects by only the two views corresponding to the minimum value of each

単眼画像入力型ビューベース3Dモデル検索に関する研究

Tohoku University北村喜文課

Analyse de forme appliquée à des modèles CAO B-Rep pour extraire des symétries locales et globales

Symmetry properties of objects described as B-Rep CAD models are analyzed locally as well as globally through an approach of type divide-and-conquer. The boundary of the object is defined using canonical surfaces frequently used when shaping mechanical components. Then, the first phase consists in generating maximal faces and edges that are independent from the object modelling process but that preserve its symmetry properties. These faces and edges form infinite sets of points that are processed globally. The second phase is the division one that creates candidate symmetry planes and axes attached to the previous maximal edges and faces. Finally, comes the propagation step of these candidate symmetry planes and axes forming the conquer phase that determines the local as well as the global symmetries of the object while characterizing its asymmetric areas.Les propriétés de symétrie d'un objet représenté sous la forme d'un modèle B-Rep CAO sont analysées localement et globalement à travers une approche de type diviser pour conquérir. La surface frontière de l'objet est décrite à partir de surfaces canoniques fréquemment utilisées dans les formes de composants mécaniques. La première phase de l'analyse consiste en la génération de faces et d'arêtes maximales indépendantes du processus de modélisation de l'objet mais préservant ses propriétés de symétrie. Ces faces et arêtes constituent des ensembles infinis de points traités globalement. La seconde phase est l'étape de division consistant en la création de plan et axes de symétrie de candidats pour les faces et arêtes maximales générées précédemment. Enfin, suit l'étape de propagation de ces plans et axes de symétrie représentant la phase de conquête et déterminant les propriétés de symétrie locales et globales de l'objet et caractérisant ses zones non-symétriques

Dictionary of Invertebrate Zoology

An exhaustive dictionary of over 13,000 terms relating to invertebrate zoology, including etymologies, word derivations and taxonomic classification. Entries cover parasitology, nematology, marine invertebrates, insects, and anatomy, biology, and reproductive processes for the following phyla: Acanthocephala Annelida Arthropoda Brachiopoda Bryozoa Chaetognatha Cnidaria Ctenophora Echinodermata Echiura Entoprocta Gastrotricha Gnathostomulida Kinorhyncha Loricifera Mesozoa Mollusca Nemata Nematomorpha Nemertea Onychophora Pentastoma Phoronida Placozoa Platyhelminthes Pogonophora Porifera Priapula Rotifera Sipuncula Tardigrada.https://digitalcommons.unl.edu/zeabook/1061/thumbnail.jp

Abstracts on Radio Direction Finding (1899 - 1995)

The files on this record represent the various databases that originally composed the CD-ROM issue of "Abstracts on Radio Direction Finding" database, which is now part of the Dudley Knox Library's Abstracts and Selected Full Text Documents on Radio Direction Finding (1899 - 1995) Collection. (See Calhoun record https://calhoun.nps.edu/handle/10945/57364 for further information on this collection and the bibliography). Due to issues of technological obsolescence preventing current and future audiences from accessing the bibliography, DKL exported and converted into the three files on this record the various databases contained in the CD-ROM. The contents of these files are: 1) RDFA_CompleteBibliography_xls.zip [RDFA_CompleteBibliography.xls: Metadata for the complete bibliography, in Excel 97-2003 Workbook format; RDFA_Glossary.xls: Glossary of terms, in Excel 97-2003 Workbookformat; RDFA_Biographies.xls: Biographies of leading figures, in Excel 97-2003 Workbook format]; 2) RDFA_CompleteBibliography_csv.zip [RDFA_CompleteBibliography.TXT: Metadata for the complete bibliography, in CSV format; RDFA_Glossary.TXT: Glossary of terms, in CSV format; RDFA_Biographies.TXT: Biographies of leading figures, in CSV format]; 3) RDFA_CompleteBibliography.pdf: A human readable display of the bibliographic data, as a means of double-checking any possible deviations due to conversion

Ohio State University Bulletin

Classes available for students to enroll in during the 1983-1984 academic year for The Ohio State University