12,395 research outputs found

    Using image morphing for memory-efficient impostor rendering on GPU

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    Real-time rendering of large animated crowds consisting thousands of virtual humans is important for several applications including simulations, games and interactive walkthroughs; but cannot be performed using complex polygonal models at interactive frame rates. For that reason, several methods using large numbers of pre-computed image-based representations, which are called as impostors, have been proposed. These methods take the advantage of existing programmable graphics hardware to compensate the computational expense while maintaining the visual fidelity. Making the number of different virtual humans, which can be rendered in real-time, not restricted anymore by the required computational power but by the texture memory consumed for the variety and discretization of their animations. In this work, we proposed an alternative method that reduces the memory consumption by generating compelling intermediate textures using image-morphing techniques. In order to demonstrate the preserved perceptual quality of animations, where half of the key-frames were rendered using the proposed methodology, we have implemented the system using the graphical processing unit and obtained promising results at interactive frame rates

    Fast determination of coarse grained cell anisotropy and size in epithelial tissue images using Fourier transform

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    Mechanical strain and stress play a major role in biological processes such as wound healing or morphogenesis. To assess this role quantitatively, fixed or live images of tissues are acquired at a cellular precision in large fields of views. To exploit these data, large numbers of cells have to be analyzed to extract cell shape anisotropy and cell size. Most frequently, this is performed through detailed individual cell contour determination, using so-called segmentation computer programs, complemented if necessary by manual detection and error corrections. However, a coarse grained and faster technique can be recommended in at least three situations. First, when detailed information on individual cell contours is not required, for instance in studies which require only coarse-grained average information on cell anisotropy. Second, as an exploratory step to determine whether full segmentation can be potentially useful. Third, when segmentation is too difficult, for instance due to poor image quality or too large a cell number. We developed a user-friendly, Fourier transform-based image analysis pipeline. It is fast (typically 10410^4 cells per minute with a current laptop computer) and suitable for time, space or ensemble averages. We validate it on one set of artificial images and on two sets of fully segmented images, one from a Drosophila pupa and the other from a chicken embryo; the pipeline results are robust. Perspectives include \textit{in vitro} tissues, non-biological cellular patterns such as foams, and xyzxyz stacks.Comment: 13 pages; 9 figure

    Coordinated regulation of chromatophore differentiation and melanogenesis during the ontogeny of skin pigmentation of Solea senegalensis (Kaup, 1858)

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    Abnormal pigmentation of Senegalese sole has been described as one problem facing the full exploitation of its commercial production. To improve our understanding of flatfish pigmentation of this commercially important species we have evaluated eleven genes related to two different processes of pigmentation: melanophore differentiation, and melanin production. The temporal distribution of gene expression peaks corresponds well with changes in pigmentation patterns and the intensity of skin melanization. Several gene ratios were also examined to put in perspective possible genetic markers for the different stages of normal pigmentation development. Further, the phenotypic changes that occur during morphogenesis correspond well with the main transitions in gene expression that occur. Given the dramatic phenotypic alterations which flatfish undergo, including the asymmetric coloration that occurs between the ocular and the blind side, and the synchrony of the two processes of morphogenesis and pigmentation ontogenesis, these species constitute an interesting model for the study of pigmentation. In this study we present a first approximation towards explaining the genetic mechanisms for regulating pigmentation ontogeny in Senegalese sole, Solea senegalensis.Ministry of Science and Innovation (MICIIN) of the Spanish Government [AGL2008-03897-C04-01/ACU]; European Community [FP7/2007-2013-222719-LIFECYCLE]; Spanish Governmentinfo:eu-repo/semantics/publishedVersio

    Subjectivity in contemporary visualization of reality: re-visiting Ottoman miniatures

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    Though Ottoman miniatures are 2D representations, they carry the potential of conveying an individual’s perception in a more detailed manner as compared to 3D perspective renderings. In a typical 2-vanishing-point perspective; objects / subjects drawn in the foreground hide the ones that are located at their back: This phenomenon is called occlusion. In Ottoman miniatures there is no occlusion, all object / subject illustrations are wholistic, there is no partial description of figures. Consequently, you end up with a life form that is the synthesis of individual forms, a sui generis state... This unique visual narrative can be extended to cubist works where multifaceted descriptions are observed. Another advantage of Ottoman miniatures is that hierarchies of image and image maker are quite clear. Miniatures make use of distance, void, shape, scale relationships and their layout to give a sense of depth in space. Though objectivity is very much valued in visual representation, ideal objectivity is not possible since representations are created by subjects and subjects belong to cultures that have different criteria in forming / perceiving portrayals. Moreover, tools that are used for visual representations usually prove to be narrower than the scope of human perception. Departing from the point of view explained above, Muta-morphosis is a photography project that is created as an almost surreal visualization stemming from the real. The lack of a single perspectival structure due to multiplicity of perspectives after compressed panoramic imaging, can be linked to Ottoman miniatures, which in turn, connects the global contemporary representation to its local traditional counterpart. Keywords: Ottoman miniature painting, contemporary photography, child drawings, visualization, representation, reality, documentary, subjectivity, objectivity, visual narration

    Most Likely Separation of Intensity and Warping Effects in Image Registration

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    This paper introduces a class of mixed-effects models for joint modeling of spatially correlated intensity variation and warping variation in 2D images. Spatially correlated intensity variation and warp variation are modeled as random effects, resulting in a nonlinear mixed-effects model that enables simultaneous estimation of template and model parameters by optimization of the likelihood function. We propose an algorithm for fitting the model which alternates estimation of variance parameters and image registration. This approach avoids the potential estimation bias in the template estimate that arises when treating registration as a preprocessing step. We apply the model to datasets of facial images and 2D brain magnetic resonance images to illustrate the simultaneous estimation and prediction of intensity and warp effects
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