This paper presents a new approach to 3D object recognition by using an Octree model library (OML) I, II and fast search algorithm. The fast search algorithm is used for finding the 4 pairs of feature points to estimate the viewing direction uses on effective two level database. The method is based on matching the object contour to the reference occluded shapes of 49, 118 viewing directions. The initially bestmatched viewing direction is calibrated by searching for the 4 pairs of feature points between the input image and the image projected along the estimated viewing direction. At this point, the input shape is recognized by matching it to the projected shape. The computational complexity of the proposed method is shown to be O(n^2) in the worst case, and that of the simple combinatorial method of O(m^4,n^2), where n and m denote the number of feature points of the 3D model object and the 2D object, respectively.
The article presents an experimental method for the three-dimensional (3D) imaging of ferroelectric domain structures using the method of digital holographic tomography. The implementation of this method uses curvilinear filtered back-projection. Our experimental method is tested by the visualization of the domain structures in the periodically poled lithium niobate single crystal. The developed method enables fast and accurate 3D observation of structures of ferroelectric domains in the whole volume of ferroelectric single crystals. and Článek prezentuje experimentální metodu pro trojrozměrné (3D) zobrazování feroelektrických doménových struktur za použití metody digitální holografické tomografie. Implementace této metody využívá křivočarou filtrovanou zpětnou projekci. Naše experimentální metoda je testována na zobrazování doménových struktur v periodicky polarizovaném monokrystalu niobátu lithia. Vyvinutá metoda umožňuje rychlé a přesné 3D pozorování struktur feroelektrických domén v celém objemu feroelektrických monokrystalů v milimetrovém měřítku.
A (0, 2)-graph is a connected graph, where each pair of vertices has either 0 or 2 common neighbours. These graphs constitute a subclass of (0, λ)-graphs introduced by Mulder in 1979. A rectagraph, well known in diagram geometry, is a triangle-free (0, 2)-graph. (0, 2)-graphs include hypercubes, folded cube graphs and some particular graphs such as icosahedral graph, Shrikhande graph, Klein graph, Gewirtz graph, etc. In this paper, we give some local properties of 4-cycles in (0, λ)-graphs and more specifically in (0, 2)-graphs, leading to new characterizations of rectagraphs and hypercubes., Khadra Bouanane, Abdelhafid Berrachedi., and Obsahuje bibliografii
On a 4-dimensional anti-Kähler manifold, its zero scalar curvature implies that its Weyl curvature vanishes and vice versa. In particular any 4-dimensional anti-Kähler manifold with zero scalar curvature is flat.