Search results for "graphics"
showing 10 items of 1223 documents
Beware of contagion!
2003
Landscape ecology starts from the assumption that diversity and spatial arrangement of ecosystem mosaics has ecological implications and tries to understand the interactions between diversity and structure of large spatially heterogeneous areas and its ecological functions. This approach implies effective use of earth observation techniques and geographic information systems, enabling a global view of the landscape mosaics. Consequently, a large number of indices has been used to quantify the structure of categorical maps as a surrogate of actual landscapes and correlate them to ecological processes. In particular, the entropy-based contagion index has been extensively used to summarize the…
A Multi-Projector Calibration Method for Virtual Reality Simulators with Analytically Defined Screens
2017
The geometric calibration of projectors is a demanding task, particularly for the industry of virtual reality simulators. Different methods have been developed during the last decades to retrieve the intrinsic and extrinsic parameters of projectors, most of them being based on planar homographies and some requiring an extended calibration process. The aim of our research work is to design a fast and user-friendly method to provide multi-projector calibration on analytically defined screens, where a sample is shown for a virtual reality Formula 1 simulator that has a cylindrical screen. The proposed method results from the combination of surveying, photogrammetry and image processing approac…
Towards a Guidance System to Aid in the Dosimetry Calculation of Intraoperative Electron Radiation Therapy
2015
In Intraoperative Electron Radiation Therapy (IOERT), the lack of specific planning tools limits its applicability, the need for accurate dosimetry estimation and application during the therapy being the most critical. Recently, some works have been presented that try to overcome some of the limitations for establishing planning tools, though still an accurate guidance system that tracks, in real-time, the applicator and the patient is needed. In these surgical environments, the acquisition of an accurate 3D shape of the patient’s tumor bed in real-time is of high interest, as current systems make use of a 3D model acquired before the treatment. In this paper, an optical-based system is pre…
Reverse Catmull-Clark Subdivision
2006
Reverse subdivision consists in constructing a coarse mesh of a model from a finer mesh of this same model. In this paper, we give formulas for reverse Catmull-Clark subdivision. These formulas allow the constructing of a coarse mesh for almost all meshes. The condition for being able to apply these formulas is that the mesh to be reversed must be generated by the subdivision of a coarse mesh. Except for this condition, the mesh can be arbitrary. Vertices can be regular or extraordinary and the mesh itself can be arbitrary (triangular, quadrilateral…).
Ositusmetodit reaaliaikaisessa renderöinnissä
2017
Tietokonegrafiikka ja siihen liittyvät menetelmät ovat nopeasti kehittyvä tutkimuksen ala. Tämän tutkimuksen tavoitteena on pohtia eri ositusmenetelmien toimintaa reaaliaikaisessa käytössä sekä vertailla näitä menetelmiä. Nykyaikaiselle käytölle tehokkaimmaksi osoittautui kolmesta tutkitusta menetelmästä tuorein (Brainerd ym. 2016). Tulevassa tutkimuksessa laitteistointegraatioon keskittyminen voisi tuoda ositusmenetelmät nopeammin kuluttajien saataville. Computergraphicsanditsmethodsarearapidlydevelopingfieldinresearch.The purpose of this study is to discuss and compare the functionality of several subdivision methods in real-time use. The latest of the three studied methods turned out to be…
Use of driving simulators for advanced driver assistance Systems evaluation in emergency situations
2012
Introducing advanced driver assistance systems in cars has numerous consequences, particularly on drivers' behavior and their interaction with the vehicle. The expected safety benefits of assistance systems can thus be jeopardized. In order to assess the actual safety benefits, driving simulators offer a safe and cheap alternative. This doctoral work relies on experiments carried out on driving simulators with different assistance systems. A first experimental part focuses on longitudinal control assistance: we studied drivers' familiarization with a Forward Collision Warning system in critical situations. A second experimental part focuses on lateral control assistance: we studied drivers'…
Interface Detection Using a Quenched-Noise Version of the Edwards-Wilkinson Equation
2015
We report here a multipurpose dynamic-interface-based segmentation tool, suitable for segmenting planar, cylindrical, and spherical surfaces in 3D. The method is fast enough to be used conveniently even for large images. Its implementation is straightforward and can be easily realized in many environments. Its memory consumption is low, and the set of parameters is small and easy to understand. The method is based on the Edwards-Wilkinson equation, which is traditionally used to model the equilibrium fluctuations of a propagating interface under the influence of temporally and spatially varying noise. We report here an adaptation of this equation into multidimensional image segmentation, an…
Designing browsing for in-car music player
2012
User interface features of a touch based mobile music player and their comparative impact on driver distraction when searching music albums were investigated. In a driving simulator experiment (N=18) three scrolling methods buttons, swipe and kinetic were compared, whereat the number of music tracks presented in a list-style format varied between three, five and seven items per page. Half of the participants used the music player in a portrait mode and half of them in a landscape mode. It was expected that swipe supports less severe distraction effects than kinetic or button due to systematic page-by-page scrolling and low levels of pointing accuracy required for browsing. Three items shoul…
Automatic dynamic texture segmentation using local descriptors and optical flow
2012
A dynamic texture (DT) is an extension of the texture to the temporal domain. How to segment a DT is a challenging problem. In this paper, we address the problem of segmenting a DT into disjoint regions. A DT might be different from its spatial mode (i.e., appearance) and/or temporal mode (i.e., motion field). To this end, we develop a framework based on the appearance and motion modes. For the appearance mode, we use a new local spatial texture descriptor to describe the spatial mode of the DT; for the motion mode, we use the optical flow and the local temporal texture descriptor to represent the temporal variations of the DT. In addition, for the optical flow, we use the histogram of orie…
Lattice Boltzmann Simulations at Petascale on Multi-GPU Systems with Asynchronous Data Transfer and Strictly Enforced Memory Read Alignment
2015
The lattice Boltzmann method is a well-established numerical approach for complex fluid flow simulations. Recently general-purpose graphics processing units have become accessible as high-performance computing resources at large-scale. We report on implementing a lattice Boltzmann solver for multi-GPU systems that achieves 0.69 PFLOPS performance on 16384 GPUs. In addition to optimizing the data layout on the GPUs and eliminating the halo sites, we make use of the possibility to overlap data transfer between the host CPU and the device GPU with computing on the GPU. We simulate flow in porous media and measure both strong and weak scaling performance with the emphasis being on a large scale…