Browsing by Author "Wimmer, Michael"
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Item Conservative Meshlet Bounds for Robust Culling of Skinned Meshes(The Eurographics Association and John Wiley & Sons Ltd., 2021) Unterguggenberger, Johannes; Kerbl, Bernhard; Pernsteiner, Jakob; Wimmer, Michael; Zhang, Fang-Lue and Eisemann, Elmar and Singh, KaranFollowing recent advances in GPU hardware development and newly introduced rendering pipeline extensions, the segmentation of input geometry into small geometry clusters-so-called meshlets-has emerged as an important practice for efficient rendering of complex 3D models. Meshlets can be processed efficiently using mesh shaders on modern graphics processing units, in order to achieve streamlined geometry processing in just two tightly coupled shader stages that allow for dynamic workload manipulation in-between. The additional granularity layer between entire models and individual triangles enables new opportunities for fine-grained visibility culling methods. However, in contrast to static models, view frustum and backface culling on a per-meshlet basis for skinned, animated models are difficult to achieve while respecting the conservative spatio-temporal bounds that are required for robust rendering results. In this paper, we describe a solution for computing and exploiting relevant conservative bounds for culling meshlets of models that are animated using linear blend skinning. By enabling visibility culling for animated meshlets, our approach can help to improve rendering performance and alleviate bottlenecks in the notoriously performanceand memory-intensive skeletal animation pipelines of modern real-time graphics applications.Item EUROGRAPHICS 2021: Short Papers Frontmatter(Eurographics Association, 2021) Theisel, Holger; Wimmer, Michael; Theisel, Holger and Wimmer, MichaelItem Fast Multi-View Rendering for Real-Time Applications(The Eurographics Association, 2020) Unterguggenberger, Johannes; Kerbl, Bernhard; Steinberger, Markus; Schmalstieg, Dieter; Wimmer, Michael; Frey, Steffen and Huang, Jian and Sadlo, FilipEfficient rendering of multiple views can be a critical performance factor for real-time rendering applications. Generating more than one view multiplies the amount of rendered geometry, which can cause a huge performance impact. Minimizing that impact has been a target of previous research and GPU manufacturers, who have started to equip devices with dedicated acceleration units. However, vendor-specific acceleration is not the only option to increase multi-view rendering (MVR) performance. Available graphics API features, shader stages and optimizations can be exploited for improved MVR performance, while generally offering more versatile pipeline configurations, including the preservation of custom tessellation and geometry shaders. In this paper, we present an exhaustive evaluation of MVR pipelines available on modern GPUs. We provide a detailed analysis of previous techniques, hardware-accelerated MVR and propose a novel method, leading to the creation of an MVR catalogue. Our analyses cover three distinct applications to help gain clarity on overall MVR performance characteristics. Our interpretation of the observed results provides a guideline for selecting the most appropriate one for various use cases on different GPU architectures.Item Fast Out-of-Core Octree Generation for Massive Point Clouds(The Eurographics Association and John Wiley & Sons Ltd., 2020) Schütz, Markus; Ohrhallinger, Stefan; Wimmer, Michael; Eisemann, Elmar and Jacobson, Alec and Zhang, Fang-LueWe propose an efficient out-of-core octree generation method for arbitrarily large point clouds. It utilizes a hierarchical counting sort to quickly split the point cloud into small chunks, which are then processed in parallel. Levels of detail are generated by subsampling the full data set bottom up using one of multiple exchangeable sampling strategies.We introduce a fast hierarchical approximate blue-noise strategy and compare it to a uniform random sampling strategy. The throughput, including out-of-core access to disk, generating the octree, and writing the final result to disk, is about an order of magnitude faster than the state of the art, and reaches up to around 6 million points per second for the blue-noise approach and up to around 9 million points per second for the uniform random approach on modern SSDs.Item Frontmatter: Eurographics Workshop on Graphics and Cultural Heritage(The Eurographics Association, 2018) Sablatnig, Robert; Wimmer, Michael; Sablatnig, Robert and Wimmer, MichaelItem GPU-Accelerated LOD Generation for Point Clouds(The Eurographics Association and John Wiley & Sons Ltd., 2023) Schütz, Markus; Kerbl, Bernhard; Klaus, Philip; Wimmer, Michael; Bikker, Jacco; Gribble, ChristiaanAbout: We introduce a GPU-accelerated LOD construction process that creates a hybrid voxel-point-based variation of the widely used layered point cloud (LPC) structure for LOD rendering and streaming. The massive performance improvements provided by the GPU allow us to improve the quality of lower LODs via color filtering while still increasing construction speed compared to the non-filtered, CPU-based state of the art. Background: LOD structures are required to render hundreds of millions to trillions of points, but constructing them takes time. Results: LOD structures suitable for rendering and streaming are constructed at rates of about 1 billion points per second (with color filtering) to 4 billion points per second (sample-picking/random sampling, state of the art) on an RTX 3090 - an improvement of a factor of 80 to 400 times over the CPU-based state of the art (12 million points per second). Due to being in-core, model sizes are limited to about 500 million points per 24GB memory. Discussion: Our method currently focuses on maximizing in-core construction speed on the GPU. Issues such as out-of-core construction of arbitrarily large data sets are not addressed, but we expect it to be suitable as a component of bottom-up out-of-core LOD construction schemes.Item An Improved Triangle Encoding Scheme for Cached Tessellation(The Eurographics Association, 2022) Kerbl, Bernhard; Horváth, Linus; Cornel, Daniel; Wimmer, Michael; Pelechano, Nuria; Vanderhaeghe, DavidWith the recent advances in real-time rendering that were achieved by embracing software rasterization, the interest in alternative solutions for other fixed-function pipeline stages rises. In this paper, we revisit a recently presented software approach for cached tessellation, which compactly encodes and stores triangles in GPU memory. While the proposed technique is both efficient and versatile, we show that the original encoding is suboptimal and provide an alternative scheme that acts as a drop-in replacement. As shown in our evaluation, the proposed modifications can yield performance gains of 40% and more.Item Interactive Visualization of Flood and Heavy Rain Simulations(The Eurographics Association and John Wiley & Sons Ltd., 2019) Cornel, Daniel; Buttinger-Kreuzhuber, Andreas; Konev, Artem; Horváth, Zsolt; Wimmer, Michael; Heidrich, Raimund; Waser, Jürgen; Gleicher, Michael and Viola, Ivan and Leitte, HeikeIn this paper, we present a real-time technique to visualize large-scale adaptive height fields with C1-continuous surface reconstruction. Grid-based shallow water simulation is an indispensable tool for interactive flood management applications. Height fields defined on adaptive grids are often the only viable option to store and process the massive simulation data. Their visualization requires the reconstruction of a continuous surface from the spatially discrete simulation data. For regular grids, fast linear and cubic interpolation are commonly used for surface reconstruction. For adaptive grids, however, there exists no higher-order interpolation technique fast enough for interactive applications. Our proposed technique bridges the gap between fast linear and expensive higher-order interpolation for adaptive surface reconstruction. During reconstruction, no matter if regular or adaptive, discretization and interpolation artifacts can occur, which domain experts consider misleading and unaesthetic. We take into account boundary conditions to eliminate these artifacts, which include water climbing uphill, diving towards walls, and leaking through thin objects. We apply realistic water shading with visual cues for depth perception and add waves and foam synthesized from the simulation data to emphasize flow directions. The versatility and performance of our technique are demonstrated in various real-world scenarios. A survey conducted with domain experts of different backgrounds and concerned citizens proves the usefulness and effectiveness of our technique.Item Parameter-Free and Improved Connectivity for Point Clouds(The Eurographics Association, 2023) Marin, Diana; Ohrhallinger, Stefan; Wimmer, Michael; Singh, Gurprit; Chu, Mengyu (Rachel)Determining connectivity in unstructured point clouds is a long-standing problem that is still not addressed satisfactorily. In this poster, we propose an extension to the proximity graph introduced in [MOW22] to three-dimensional models. We use the spheres-of-influence (SIG) proximity graph restricted to the 3D Delaunay graph to compute connectivity between points. Our approach shows a better encoding of the connectivity in relation to the ground truth than the k-nearest neighborhood (kNN) for a wide range of k values, and additionally, it is parameter-free. Our result for this fundamental task offers potential for many applications relying on kNN, e.g., improvements in normal estimation, surface reconstruction, motion planning, simulations, and many more.Item Photorealistic Material Editing Through Direct Image Manipulation(The Eurographics Association and John Wiley & Sons Ltd., 2020) Zsolnai-Fehér, Károly; Wonka, Peter; Wimmer, Michael; Dachsbacher, Carsten and Pharr, MattCreating photorealistic materials for light transport algorithms requires carefully fine-tuning a set of material properties to achieve a desired artistic effect. This is typically a lengthy process that involves a trained artist with specialized knowledge. In this work, we present a technique that aims to empower novice and intermediate-level users to synthesize high-quality photorealistic materials by only requiring basic image processing knowledge. In the proposed workflow, the user starts with an input image and applies a few intuitive transforms (e.g., colorization, image inpainting) within a 2D image editor of their choice, and in the next step, our technique produces a photorealistic result that approximates this target image. Our method combines the advantages of a neural network-augmented optimizer and an encoder neural network to produce high-quality output results within 30 seconds. We also demonstrate that it is resilient against poorly-edited target images and propose a simple extension to predict image sequences with a strict time budget of 1-2 seconds per image.Item Precomputed Radiative Heat Transport for Efficient Thermal Simulation(The Eurographics Association and John Wiley & Sons Ltd., 2023) Freude, Christian; Hahn, David; Rist, Florian; Lipp, Lukas; Wimmer, Michael; Chaine, Raphaëlle; Deng, Zhigang; Kim, Min H.Architectural design and urban planning are complex design tasks. Predicting the thermal impact of design choices at interactive rates enhances the ability of designers to improve energy efficiency and avoid problematic heat islands while maintaining design quality. We show how to use and adapt methods from computer graphics to efficiently simulate heat transfer via thermal radiation, thereby improving user guidance in the early design phase of large-scale construction projects and helping to increase energy efficiency and outdoor comfort. Our method combines a hardware-accelerated photon tracing approach with a carefully selected finite element discretization, inspired by precomputed radiance transfer. This combination allows us to precompute a radiative transport operator, which we then use to rapidly solve either steady-state or transient heat transport throughout the entire scene. Our formulation integrates time-dependent solar irradiation data without requiring changes in the transport operator, allowing us to quickly analyze many different scenarios such as common weather patterns, monthly or yearly averages, or transient simulations spanning multiple days or weeks. We show how our approach can be used for interactive design workflows such as city planning via fast feedback in the early design phase.Item Progressive Real-Time Rendering of One Billion Points Without Hierarchical Acceleration Structures(The Eurographics Association and John Wiley & Sons Ltd., 2020) Schütz, Markus; Mandlburger, Gottfried; Otepka, Johannes; Wimmer, Michael; Panozzo, Daniele and Assarsson, UlfResearch in rendering large point clouds traditionally focused on the generation and use of hierarchical acceleration structures that allow systems to load and render the smallest fraction of the data with the largest impact on the output. The generation of these structures is slow and time consuming, however, and therefore ill-suited for tasks such as quickly looking at scan data stored in widely used unstructured file formats, or to immediately display the results of point-cloud processing tasks. We propose a progressive method that is capable of rendering any point cloud that fits in GPU memory in real time, without the need to generate hierarchical acceleration structures in advance. Our method supports data sets with a large amount of attributes per point, achieves a load performance of up to 100 million points per second, displays already loaded data in real time while remaining data is still being loaded, and is capable of rendering up to one billion points using an on-the-fly generated shuffled vertex buffer as its data structure, instead of slow-to-generate hierarchical structures. Shuffling is done during loading in order to allow efficiently filling holes with random subsets, which leads to a higher quality convergence behavior.Item Quantifying the Error of Light Transport Algorithms(The Eurographics Association and John Wiley & Sons Ltd., 2019) Celarek, Adam; Jakob, Wenzel; Wimmer, Michael; Lehtinen, Jaakko; Boubekeur, Tamy and Sen, PradeepThis paper proposes a new methodology for measuring the error of unbiased physically based rendering algorithms. The current state of the art includes mean squared error (MSE) based metrics and visual comparisons of equal-time renderings of competing algorithms. Neither is satisfying as MSE does not describe behavior and can exhibit significant variance, and visual comparisons are inherently subjective. Our contribution is two-fold: First, we propose to compute many short renderings instead of a single long run and use the short renderings to estimate MSE expectation and variance as well as per-pixel standard deviation. An algorithm that achieves good results in most runs, but with occasional outliers is essentially unreliable, which we wish to quantify numerically. We use per-pixel standard deviation to identify problematic lighting effects of rendering algorithms. The second contribution is the error spectrum ensemble (ESE), a tool for measuring the distribution of error over frequencies. The ESE serves two purposes: It reveals correlation between pixels and can be used to detect outliers, which offset the amount of error substantially.Item Rendering Point Clouds with Compute Shaders and Vertex Order Optimization(The Eurographics Association and John Wiley & Sons Ltd., 2021) Schütz, Markus; Kerbl, Bernhard; Wimmer, Michael; Bousseau, Adrien and McGuire, MorganIn this paper, we present several compute-based point cloud rendering approaches that outperform the hardware pipeline by up to an order of magnitude and achieve significantly better frame times than previous compute-based methods. Beyond basic closest-point rendering, we also introduce a fast, high-quality variant to reduce aliasing. We present and evaluate several variants of our proposed methods with different flavors of optimization, in order to ensure their applicability and achieve optimal performance on a range of platforms and architectures with varying support for novel GPU hardware features. During our experiments, the observed peak performance was reached rendering 796 million points (12.7GB) at rates of 62 to 64 frames per second (50 billion points per second, 802GB/s) on an RTX 3090 without the use of level-of-detail structures. We further introduce an optimized vertex order for point clouds to boost the efficiency of GL_POINTS by a factor of 5x in cases where hardware rendering is compulsory. We compare different orderings and show that Morton sorted buffers are faster for some viewpoints, while shuffled vertex buffers are faster in others. In contrast, combining both approaches by first sorting according to Morton-code and shuffling the resulting sequence in batches of 128 points leads to a vertex buffer layout with high rendering performance and low sensitivity to viewpoint changes.Item The Road to Vulkan: Teaching Modern Low-Level APIs in Introductory Graphics Courses(The Eurographics Association, 2022) Unterguggenberger, Johannes; Kerbl, Bernhard; Wimmer, Michael; Bourdin, Jean-Jacques; Paquette, EricFor over two decades, the OpenGL API provided users with the means for implementing versatile, feature-rich, and portable real-time graphics applications. Consequently, it has been widely adopted by practitioners and educators alike and is deeply ingrained in many curricula that teach real-time graphics for higher education. Over the years, the architecture of graphics processing units (GPUs) incrementally diverged from OpenGL's conceptual design. The more recently introduced Vulkan API provides a more modern, fine-grained approach for interfacing with the GPU. Various properties of this API and overall trends suggest that Vulkan could soon replace OpenGL in many areas. Hence, it stands to reason that educators who have their students' best interests at heart should provide them with corresponding lecture material. However, Vulkan is notoriously verbose and rather challenging for first-time users, thus transitioning to this new API bears a considerable risk of failing to achieve expected teaching goals. In this paper, we document our experiences after teaching Vulkan in an introductory graphics course side-by-side with conventional OpenGL. A final survey enables us to draw conclusions about perceived workload, difficulty, and students' acceptance of either approach and identify suitable conditions and recommendations for teaching Vulkan to undergraduate students.Item SIG-based Curve Reconstruction(The Eurographics Association, 2022) Marin, Diana; Ohrhallinger, Stefan; Wimmer, Michael; Sauvage, Basile; Hasic-Telalovic, JasminkaWe introduce a new method to compute the shape of an unstructured set of two-dimensional points. The algorithm exploits the to-date rarely used proximity-based graph called spheres-of-influence graph (SIG). We filter edges from the Delaunay triangulation belonging to the SIG as an initial graph and apply some additional processing plus elements from the Connect2D algorithm. This combination already shows improvements in curve reconstruction, yielding the best reconstruction accuracy compared to state-of-the-art algorithms from a recent comprehensive benchmark, and offers potential of further improvements.Item SIGDT: 2D Curve Reconstruction(The Eurographics Association and John Wiley & Sons Ltd., 2022) Marin, Diana; Ohrhallinger, Stefan; Wimmer, Michael; Umetani, Nobuyuki; Wojtan, Chris; Vouga, EtienneDetermining connectivity between points and reconstructing their shape boundaries are long-standing problems in computer graphics. One possible approach to solve these problems is to use a proximity graph. We propose a new proximity graph computed by intersecting the to-date rarely used proximity-based graph called spheres-of-influence graph (SIG) with the Delaunay triangulation (DT). We prove that the resulting graph, which we name SIGDT, contains the piece-wise linear reconstruction for a set of unstructured points in the plane for a sampling condition superseding current bounds and capturing well practical point sets' properties. As an application, we apply a dual of boundary adjustment steps from the CONNECT2D algorithm to remove the redundant edges. We show that the resulting algorithm SIG-CONNECT2D yields the best reconstruction accuracy compared to state-of-the-art algorithms from a recent comprehensive benchmark, and the method offers the potential for further improvements, e.g., for surface reconstruction.Item Software Rasterization of 2 Billion Points in Real Time(ACM Association for Computing Machinery, 2022) Schütz, Markus; Kerbl, Bernhard; Wimmer, Michael; Josef Spjut; Marc Stamminger; Victor ZordanThe accelerated collection of detailed real-world 3D data in the form of ever-larger point clouds is sparking a demand for novel visualization techniques that are capable of rendering billions of point primitives in real-time. We propose a software rasterization pipeline for point clouds that is capable of rendering up to two billion points in real-time (60 FPS) on commodity hardware. Improvements over the state of the art are achieved by batching points, enabling a number of batch-level optimizations before rasterizing them within the same rendering pass. These optimizations include frustum culling, level-of-detail (LOD) rendering, and choosing the appropriate coordinate precision for a given batch of points directly within a compute workgroup. Adaptive coordinate precision, in conjunction with visibility buffers, reduces the required data for the majority of points to just four bytes, making our approach several times faster than the bandwidth-limited state of the art. Furthermore, support for LOD rendering makes our software rasterization approach suitable for rendering arbitrarily large point clouds, and to meet the elevated performance demands of virtual reality applications.Item StretchDenoise: Parametric Curve Reconstruction with Guarantees by Separating Connectivity from Residual Uncertainty of Samples(The Eurographics Association, 2018) Ohrhallinger, Stefan; Wimmer, Michael; Fu, Hongbo and Ghosh, Abhijeet and Kopf, JohannesWe reconstruct a closed denoised curve from an unstructured and highly noisy 2D point cloud. Our proposed method uses a two-pass approach: Previously recovered manifold connectivity is used for ordering noisy samples along this manifold and express these as residuals in order to enable parametric denoising. This separates recovering low-frequency features from denoising high frequencies, which avoids over-smoothing. The noise probability density functions (PDFs) at samples are either taken from sensor noise models or from estimates of the connectivity recovered in the first pass. The output curve balances the signed distances (inside/outside) to the samples. Additionally, the angles between edges of the polygon representing the connectivity become minimized in the least-square sense. The movement of the polygon's vertices is restricted to their noise extent, i.e., a cut-off distance corresponding to a maximum variance of the PDFs. We approximate the resulting optimization model, which consists of higher-order functions, by a linear model with good correspondence. Our algorithm is parameter-free and operates fast on the local neighborhoods determined by the connectivity. This enables us to guarantee stochastic error bounds for sampled curves corrupted by noise, e.g., silhouettes from sensed data, and we improve on the reconstruction error from ground truth. Source code is available online. An extended version is available at: https://arxiv.org/abs/1808.07778Item Temporally Stable Content-Adaptive and Spatio-Temporal Shading Rate Assignment for Real-Time Applications(The Eurographics Association, 2021) Stappen, Stefan; Unterguggenberger, Johannes; Kerbl, Bernhard; Wimmer, Michael; Lee, Sung-Hee and Zollmann, Stefanie and Okabe, Makoto and Wünsche, BurkhardWe propose two novel methods to improve the efficiency and quality of real-time rendering applications: Texel differential-based content-adaptive shading (TDCAS) and spatio-temporally filtered adaptive shading (STeFAS). Utilizing Variable Rate Shading (VRS)-a hardware feature introduced with NVIDIA's Turing micro-architecture-and properties derived during rendering or Temporal Anti-Aliasing (TAA), our techniques adapt the resolution to improve the performance and quality of real-time applications. VRS enables different shading resolution for different regions of the screen during a single render pass. In contrast to other techniques, TDCAS and STeFAS have very little overhead for computing the shading rate. STeFAS enables up to 4x higher rendering resolutions for similar frame rates, or a performance increase of 4× at the same resolution.