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Item A Parallel Approach to Compression and Decompression of Triangle Meshes using the GPU(The Eurographics Association and John Wiley & Sons Ltd., 2017) Jakob, Johannes; Buchenau, Christoph; Guthe, Michael; Bærentzen, Jakob Andreas and Hildebrandt, KlausMost state-of-the-art compression algorithms use complex connectivity traversal and prediction schemes, which are not efficient enough for online compression of large meshes. In this paper we propose a scalable massively parallel approach for compression and decompression of large triangle meshes using the GPU. Our method traverses the input mesh in a parallel breadth-first manner and encodes the connectivity data similarly to the well known cut-border machine. Geometry data is compressed using a local prediction strategy. In contrast to the original cut-border machine, we can additionally handle triangle meshes with inconsistently oriented faces. Our approach is more than one order of magnitude faster than currently used methods and achieves competitive compression rates.Item 3-D Digital Preservation of At-Risk Global Cultural Heritage(The Eurographics Association, 2016) Lercari, Nicola; Shulze, Jurgen; Wendrich, Willeke; Porter, Benjamin; Burton, Margie; Levy, Thomas E.; Chiara Eva Catalano and Livio De LucaRecent current events have dramatically highlighted the vulnerability of the world's material cultural heritage. The 3-D Digital Preservation of At-Risk Global Cultural Heritage project, led by Thomas Levy at UC San Diego, catalyzes a collaborative research effort by four University of California campuses (San Diego, Berkeley, Los Angeles and Merced) to use cyberarchaeology and computer graphics for cultural heritage to document and safeguard virtually some of the most at-risk heritage objects and places. Faculty and students involved in this project are conducting path-breaking archaeological research - covering more than 10,000 years of culture and architecture - in Cyprus, Greece, Egypt, Ethiopia, Israel, Jordan, Morocco, Turkey, and the United States. This project uses the 3-D archaeological data collected in numerous at-risk heritage places to study, forecast, and model the effects of human conflict, climate change, natural disasters and technological and cultural changes on these sites and landscapes. The greater challenge undertaken by this project is to integrate archaeological heritage data and digital heritage data using the recently-announced Pacific Research Platform (PRP) and its 10-100Gb/s network as well as virtual reality kiosks installed in each participating UC campus. Our aim is to link UC San Diego and the San Diego Supercomputer Center to other labs, libraries and museums at the other UC campuses to form a highly-networked collaborative platform for curation, analysis, and visualization of 3D archaeological heritage data.Item Iso Photographic Rendering(The Eurographics Association, 2018) Porral, Philippe; Lucas, Laurent; Muller, Thomas; Randrianandrasana, Joël; Reinhard Klein and Holly RushmeierIn the field of computer graphics, the simulation of the visual appearance of materials requires an accurate computation of the light transport equation. Consequently, material models need to take into account various factors which may influence the spectral radiance perceived by the human eye. Though numerous relevant studies on the reflectance properties of materials have been conducted to date, environment maps used to simulate visual behaviors remain chiefly trichromatic. Whereas questions regarding the accurate characterization of natural lighting have been raised for some time, there are still no real sky environment maps that include both spectral radiance and polarization data. Under these conditions the simulations carried out are approximate and therefore insufficient for the industrial world where investment-sensitive decisions are often made based on these very calculations.Item Contact-Invariant Optimization for Hand Manipulation(The Eurographics Association, 2012) Mordatch, Igor; Popovic, Zoran; Todorov, Emanuel; Jehee Lee and Paul KryWe present a method for automatic synthesis of dexterous hand movements, given only high-level goals specifying what should happen to the object being manipulated. Results are presented on a wide range of tasks including grasping and picking up objects, twirling them between the fingers, tossing and catching, drawing. This work is an extension of the recent contact-invariant optimization (CIO) method, which introduced auxiliary decision variables directly specifying when and where contacts should occur, and optimized these variables together with the movement trajectory. Our contribution here is extending the unique contact model used in CIO which was specific to locomotion tasks, as well as applying the extended method systematically to hand manipulation.Item Variable Length Coding for GPU-Based Direct Volume Rendering(The Eurographics Association, 2016) Guthe, Stefan; Goesele, Michael; Matthias Hullin and Marc Stamminger and Tino WeinkaufThe sheer size of volume data sampled in a regular grid requires efficient lossless and lossy compression algorithms that allow for on-the-fly decompression during rendering. While all hardware assisted approaches are based on fixed bit rate block truncation coding, they suffer from degradation in regions of high variation while wasting space in homogeneous areas. On the other hand, vector quantization approaches using texture hardware achieve an even distribution of error in the entire volume at the cost of storing overlapping blocks or bricks. However, these approaches suffer from severe blocking artifacts that need to be smoothed over during rendering. In contrast to existing approaches, we propose to build a lossy compression scheme on top of a state-of-the-art lossless compression approach built on non-overlapping bricks by combining it with straight forward vector quantization. Due to efficient caching and load balancing, the rendering performance of our approach improves with the compression rate and can achieve interactive to real-time frame rates even at full HD resolution.Item Ray-Traced Collision Detection: Interpenetration Control and Multi-GPU Performance(The Eurographics Association, 2013) Lehericey, Francois; Gouranton, Valérie; Arnaldi, Bruno; Betty Mohler and Bruno Raffin and Hideo Saito and Oliver StaadtWe proposed in [LGA13] an iterative ray-traced collision detection algorithm (IRTCD) that exploits spatial and temporal coherency and proved to be computationally efficient but at the price of some geometrical approximations that allow more interpenetration than needed. In this paper, we present two methods to efficiently control and reduce the interpenetration without noticeable computation overhead. The first method predicts the next potentially colliding vertices. These predictions are used to make our IRTCD algorithm more robust to the above-mentioned approximations, therefore reducing the errors up to 91%. We also present a ray re-projection algorithm that improves the physical response of ray-traced collision detection algorithm. This algorithm also reduces, up to 52%, the interpenetration between objects in a virtual environment. Our last contribution shows that our algorithm, when implemented on multi-GPUs architectures, is far faster.Item Efficient GPU Based Sampling for Scene-Space Video Processing(The Eurographics Association, 2015) Klose, Felix; Wang, Oliver; Bazin, Jean-Charles; Magnor, Marcus; Sorkine-Hornung, Alexander; David Bommes and Tobias Ritschel and Thomas SchultzWe describe a method to efficiently collect and filter a large set of 2D pixel observations of unstructured 3D points, with applications to scene-space aware video processing. One of the main challenges in scene-space video processing is to achieve reasonable computation time despite the very large volumes of data, often in the order of billions of pixels. The bottleneck is determining a suitable set of candidate samples used to compute each output video pixel color. These samples are observations of the same 3D point, and must be gathered from a large number of candidate pixels, by volumetric 3D queries in scene-space. Our approach takes advantage of the spatial and temporal continuity inherent to video to greatly reduce the candidate set of samples by solving 3D volumetric queries directly on a series of 2D projections, using out-of-core data streaming and an efficient GPU producerconsumer scheme that maximizes hardware utilization by exploiting memory locality. Our system is capable of processing over a trillion pixel samples, enabling various scene-space video processing applications on full HD video output with hundreds of frames and processing times in the order of a few minutes.Item Reduced Precision for Hardware Ray Tracing in GPUs(The Eurographics Association, 2014) Keely, Sean; Ingo Wald and Jonathan Ragan-KelleyWe propose a high performance, GPU integrated, hardware ray tracing system. We present and make use of a new analysis of ray traversal in axis aligned bounding volume hierarchies. This analysis enables compact traversal hardware through the use of reduced precision arithmetic. We also propose a new cache based technique for scheduling ray traversal. With the addition of our compact fixed function traversal unit and cache mechanism, we show that current GPU architectures are well suited for hardware accelerated ray tracing, requiring only small modifications to provide high performance. By making use of existing GPU resources we are able to keep all rays and scheduling traffic on chip and out of caches. We used simulations to estimate the performance of our architecture. Our system achieves an average ray rate of 3.4 billion rays per second while path tracing our test scenes.Item Path Tracing on Massively Parallel Neuromorphic Hardware(The Eurographics Association, 2012) Richmond, Paul; Allerton, David J.; Hamish Carr and Silvester CzannerRay tracing on parallel hardware has recently benefit from significant advances in the graphics hardware and associated software tools. Despite this, the SIMD nature of graphics card architectures is only able to perform well on groups of coherent rays which exhibit little in the way of divergence. This paper presents SpiNNaker, a massively parallel system based on low power ARM cores, as an architecture suitable for ray tracing applications. The asynchronous design allows us to demonstrate a linear performance increase with respect to the number of cores. The performance perWatt ratio achieved within the fixed point path tracing example presented is far greater than that of a multi-core CPU and similar to that of a GPU under optimal conditions.Item Packet-Oriented Streamline Tracing on Modern SIMD Architectures(The Eurographics Association, 2015) Hentschel, Bernd; Göbbert, Jens Henrik; Klemm, Michael; Springer, Paul; Schnorr, Andrea; Kuhlen, Torsten W.; C. Dachsbacher and P. NavrátilThe advection of integral lines is an important computational kernel in vector field visualization. We investigate how this kernel can profit from vector (SIMD) extensions in modern CPUs. As a baseline, we formulate a streamline tracing algorithm that facilitates auto-vectorization by an optimizing compiler. We analyze this algorithm and propose two different optimizations. Our results show that particle tracing does not per se benefit from SIMD computation. Based on a careful analysis of the auto-vectorized code, we propose an optimized data access routine and a re-packing scheme which increases average SIMD efficiency. We evaluate our approach on three different, turbulent flow fields. Our optimized approaches increase integration performance up to 5:6 over our baseline measurement. We conclude with a discussion of current limitations and aspects for future work.