Graphics Hardware Research Articles

Past forward: world's most famous teapot [Past forward

Do you recognize this teapot? Tea boffins might recognize it as a Melitta product. Computer graphics people, though, know this as the "Utah teapot." In the mid-1970s, Martin Newell created an impressive 3D model of the teapot for his Ph.D. work at the University of Utah. Other researchers adopted the iconic teapot to develop new graphics hardware and software. It also made cameo appearances in Toy Story, Monsters, Inc., and “The Simpsons,” eventually earning it the moniker of "World' Most Famous Teapot."

GPU rasterization for real-time spatial aggregation over arbitrary polygons

Visual exploration of spatial data relies heavily on spatial aggregation queries that slice and summarize the data over different regions. These queries comprise computationally-intensive point-in-polygon tests that associate data points to polygonal regions, challenging the responsiveness of visualization tools. This challenge is compounded by the sheer amounts of data, requiring a large number of such tests to be performed. Traditional pre-aggregation approaches are unsuitable in this setting since they fix the query constraints and support only rectangular regions. On the other hand, query constraints are defined interactively in visual analytics systems, and polygons can be of arbitrary shapes. In this paper, we convert a spatial aggregation query into a set of drawing operations on a canvas and leverage the rendering pipeline of the graphics hardware (GPU) to enable interactive response times. Our technique trades-off accuracy for response time by adjusting the canvas resolution, and can even provide accurate results when combined with a polygon index. We evaluate our technique on two large real-world data sets, exhibiting superior performance compared to index-based approaches.

Software to convert terrestrial LiDAR scans of natural environments into photorealistic meshes

The introduction of 3D scanning has strongly influenced environmental sciences. If the resulting point clouds can be transformed into polygon meshes, a vast range of visualisation and analysis tools can be applied. But extracting accurate meshes from large point clouds gathered in natural environments is not trivial, requiring a suite of customisable processing steps. We present Habitat3D, an open source software tool to generate photorealistic meshes from registered point clouds of natural outdoor scenes. We demonstrate its capability by extracting meshes of different environments: 8,800 m2 grassland featuring several Eucalyptus trees (combining 9 scans and 41,989,885 data points); 1,018 m2 desert densely covered by vegetation (combining 56 scans and 192,223,621 data points); a well-structured garden; and a rough, volcanic surface. The resultant reconstructions accurately preserve all spatial features with millimetre accuracy whilst reducing the memory load by up to 98.5%. This enables rapid visualisation of the environments using off-the-shelf game engines and graphics hardware.

Summed Area Tables for Cube Maps.

The original Summed Area Table (SAT) structure is designed for handling 2D rectangular data. Due to the nature of spherical functions, the SAT structure cannot handle cube maps directly. This paper proposes a new SAT structure for cube maps and develops the corresponding lookup algorithm. Our formulation starts by considering a cube map as part of an auxiliary 3D function defined in a 3D rectangular space. We interpret the 2D integration process over the cube map surface as a 3D integration over the auxiliary 3D function. One may suggest that we can create a 3D SAT for this auxiliary function, and then use the 3D SAT to achieve the 3D integration. However, it is not practical to generate or store this special 3D SAT directly. This 3D SAT has some nice properties that allow us to store it in a storage-friendly data structure, namely Summed Area Cube Map (SACM). A SACM can be stored in a standard cube map texture. The lookup algorithm of our SACM structure can be implemented efficiently on current graphics hardware. In addition, the SACM structure inherits the favorable properties of the original SAT structure.

Monte Carlo calibration to implied volatility surface under volatility models

The calibration problem of implied volatility surface under complex financial models can be formulated as a nonlinear high-dimensional optimization problem. To resolve this problem for genuine volatility models, we develop a sequential methodology termed two-stage Monte Carlo calibration method. It consists of the first stage-dimension separation for splitting parametric set into two subsets, and the second stage-standard error reduction for efficient evaluation of option prices. The first stage dimension separation aims to reduce dimensionality of the optimization problem by estimating some volatility model parameters a priori under the historical probability measure such that the total number of model parameters under an option pricing measure is significantly reduced. The second stage standard error reduction aims simultaneously to reduce variance of option payoffs by the martingale control variate algorithm, and to increase the total number of Monte Carlo simulation by the hardware graphics processing unit (GPU) for parallel computing. This two-stage Monte Carlo calibration method is capable of solving a variety of complex volatility models, including hybrid models and multifactor stochastic volatility models. Essentially, it provides a general framework to analyze backward information from the historical spot prices and the forward information from option prices.

Real-Time Screen Space Cartoon Water Rendering with the Iterative Separated Bilateral Filter

We present the improvements and new results of our method for rendering particle-based liquid simulations that runs in real-time and includes an adjustable performance/quality trade-off. Our approach smooths the fluid surface with an iterative version of the separated bilateral filter, and introduces a new method for generating foam and droplets that is appropriate for non-photorealistic styles. The entire method occurs in screen space, which avoids the usual artifacts of polygonization techniques. All the steps are implemented directly in the graphics hardware. Improvements include a new method to generate foam and droplets, visual enhancements in the optical effects generated by the interaction between water and light, and tests in a environment with support to collision of water particles with rigid bodies. Performance and visual analysis that includes comparisons with previous methods shows the applicability of our approach.

FluoRender: joint freehand segmentation and visualization for many-channel fluorescence data analysis

BackgroundImage segmentation and registration techniques have enabled biologists to place large amounts of volume data from fluorescence microscopy, morphed three-dimensionally, onto a common spatial frame. Existing tools built on volume visualization pipelines for single channel or red-green-blue (RGB) channels have become inadequate for the new challenges of fluorescence microscopy. For a three-dimensional atlas of the insect nervous system, hundreds of volume channels are rendered simultaneously, whereas fluorescence intensity values from each channel need to be preserved for versatile adjustment and analysis. Although several existing tools have incorporated support of multichannel data using various strategies, the lack of a flexible design has made true many-channel visualization and analysis unavailable. The most common practice for many-channel volume data presentation is still converting and rendering pseudosurfaces, which are inaccurate for both qualitative and quantitative evaluations.ResultsHere, we present an alternative design strategy that accommodates the visualization and analysis of about 100 volume channels, each of which can be interactively adjusted, selected, and segmented using freehand tools. Our multichannel visualization includes a multilevel streaming pipeline plus a triple-buffer compositing technique. Our method also preserves original fluorescence intensity values on graphics hardware, a crucial feature that allows graphics-processing-unit (GPU)-based processing for interactive data analysis, such as freehand segmentation. We have implemented the design strategies as a thorough restructuring of our original tool, FluoRender.ConclusionThe redesign of FluoRender not only maintains the existing multichannel capabilities for a greatly extended number of volume channels, but also enables new analysis functions for many-channel data from emerging biomedical-imaging techniques.

A GPU-Adapted Structure for Unstructured Grids

A key advantage of working with structured grids e.g., images is the ability to directly tap into the powerful machinery of linear algebra. This is not much so for unstructured grids where intermediate bookkeeping data structures stand in the way. On modern high performance computing hardware, the conventional wisdom behind these intermediate structures is further challenged by costly memory access, and more importantly by prohibitive memory resources on environments such as graphics hardware. In this paper, we bypass this problem by introducing a sparse matrix representation for unstructured grids which not only reduces the memory storage requirements but also cuts down on the bulk of data movement from global storage to the compute units. In order to take full advantage of the proposed representation, we augment ordinary matrix multiplication by means of action maps, local maps which encode the desired interaction between grid vertices. In this way, geometric computations and topological modifications translate into concise linear algebra operations. In our algorithmic formulation, we capitalize on the nature of sparse matrix-vector multiplication which allows avoiding explicit transpose computation and storage. Furthermore, we develop an efficient vectorization to the demanding assembly process of standard graph and finite element matrices.

Packing Vertex Data into Hardware-Decompressible Textures.

Most graphics hardware features memory to store textures and vertex data for rendering. However, because of the irreversible trend of increasing complexity of scenes, rendering a scene can easily reach the limit of memory resources. Thus, vertex data are preferably compressed, with a requirement that they can be decompressed during rendering. In this paper, we present a novel method to exploit existing hardware texture compression circuits to facilitate the decompression of vertex data in graphics processing unit(GPUs). This built-in hardware allows real-time, random-order decoding of data. However, vertex data must be packed into textures, and careless packing arrangements can easily disrupt data coherence. Hence, we propose an optimization approach for the best vertex data permutation that minimizes compression error. All of these result in fast and high-quality vertex data decompression for real-time rendering. To further improve the visual quality, we introduce vertex clustering to reduce the dynamic range of data during quantization. Our experiments demonstrate the effectiveness of our method for various vertex data of 3D models during rendering with the advantages of a minimized memory footprint and high frame rate.

PolarGlobe: A web-wide virtual globe system for visualizing multidimensional, time-varying, big climate data

ABSTRACTThe increasing research interest in global climate change and the rise of the public awareness have generated a significant demand for new tools to support effective visualization of big climate data in a cyber environment such that anyone from any location with an Internet connection and a web browser can easily view and comprehend the data. In response to the demand, this paper introduces a new web-based platform for visualizing multidimensional, time-varying climate data on a virtual globe. The web-based platform is built upon a virtual globe system Cesium, which is open-source, highly extendable and capable of being easily integrated into a web environment. The emerging WebGL technique is adapted to support interactive rendering of 3D graphics with hardware graphics acceleration. To address the challenges of transmitting and visualizing voluminous, complex climate data over the Internet to support real-time visualization, we develop a stream encoding and transmission strategy based on video-compression techniques. This strategy allows dynamic provision of scientific data in different precisions to balance the needs for scientific analysis and visualization cost. Approaches to represent, encode and decode processed data are also introduced in detail to show the operational workflow. Finally, we conduct several experiments to demonstrate the performance of the proposed strategy under different network conditions. A prototype, PolarGlobe, has been developed to visualize climate data in the Arctic regions from multiple angles.

Multi-thread block terrain dynamic scheduling based on three-dimensional array and Sudoku

With the increasing of the scale and resolution of terrains, graphic processing hardware meet the new challenges during the terrain rendering. To solve this problem, a dynamic scheduling algorithm based on the three-dimensional array and Sudoku is proposed in this paper. Mesh optimization and texture format conversion mode is utilized to reduce the terrain data size without quality reduction. Stratified block terrains can be then built corresponding to the three-dimensional array. Finally, these block terrains are loaded and unloaded dynamically based on Sudoku strategy according to the viewpoint position. Experimental results show that the efficiency of the proposed algorithm is significantly higher than six state-of-the-art algorithms. Consequently, our algorithm has the ability to load a great amount of terrain data with high performance in frame frequency, which achieves more fluid visual experience.

Vision-based technique for circle detection and measurement using lookup table and bitwise center accumulator.

In this paper, we proposed a fast algorithm for circle detection and measurement, which uses a lookup table and bitwise center accumulator (LUT-BCA). The LUT-BCA is a two-stage procedure. The first stage determines the candidate circle centers with normal lines produced by the lookup table and recorded by the bitwise center accumulator. The second stage computes the radius of each candidate circle center and validates these centers, which eliminates the false detections. The proposed LUT-BCA can also be easily implemented on massively parallel high-performance graphics hardware using the compute unified device architecture. Experimental results indicate that the LUT-BCA can locate circle centers and measure their radii accurately and is very suitable for real-time circle detection and measurement.

Geometry-based shading for shape depiction enhancement

Recent works on Non-Photorealistic Rendering (NPR) show that object shape enhancement requires sophisticated effects such as: surface details detection and stylized shading. To date, some rendering techniques have been proposed to overcome this issue, but most of which are limited to correlate shape enhancement functionalities to surface feature variations. Therefore, this problem still persists especially in NPR. This paper is an attempt to address this problem by presenting a new approach for enhancing shape depiction of 3D objects in NPR. We first introduce a tweakable shape descriptor that offers versatile functionalities for describing the salient features of 3D objects. Then to enhance the classical shading models, we propose a new technique called Geometry-based Shading. This technique controls reflected lighting intensities based on local geometry. Our approach works without any constraint on the choice of material or illumination. We demonstrate results obtained with Blinn-Phong shading, Gooch shading, and cartoon shading. These results prove that our approach produces more satisfying results compared with the results of previous shape depiction techniques. Finally, our approach runs on modern graphics hardware in real time, which works efficiently with interactive 3D visualization.

Some pictures of the history of automotive instrumentation

AbstractThe first in vehicle instrument was the speedometer. It was invented by Otto Schulze in 1902. Until then, drivers had to estimate their speed. The speedometer was followed by an alcohol temperature gauge. A few warning lamps surveyed the most important vehicle functions. Later, single gauges like radiator temperature, fuel gauge, and revolution counter were added to the instrumentation. They were superseded by instrument clusters combining several instruments in one housing. Even though the appearance of the instrument cluster did not change significantly from the early days, there was a steady development of the intelligence behind the panel. This huge amount of information could only be handled by graphic displays. When navigation systems came into our cars, a larger graphic display was needed. It found place in the center console. In parallel, the price decline in the computer market and the availability of high‐performing graphic hardware and software made it possible to enhance the classical functions of the instrument board to an interactive multifunctional information panel, with the dashboard being the main interface between car and driver. The windshield was the third zone where information could be placed in a favorable reading position minimizing eyes off the road time. As a consequent evolution step, augmented reality head‐up displays will soon dominate the information center of premium‐class vehicles.

BIM-Sim: Interactive Simulation of Broadband Imaging Using Mie Theory.

Understanding the structure of a scattered electromagnetic (EM) field is critical to improving the imaging process. Mechanisms such as diffraction, scattering, and interference affect an image, limiting the resolution, and potentially introducing artifacts. Simulation and visualization of scattered fields thus plays an important role in imaging science. However, EM fields are high-dimensional, making them time-consuming to simulate, and difficult to visualize. In this paper, we present a framework for interactively computing and visualizing EM fields scattered by micro and nano-particles. Our software uses graphics hardware for evaluating the field both inside and outside of these particles. We then use Monte-Carlo sampling to reconstruct and visualize the three-dimensional structure of the field, spectral profiles at individual points, the structure of the field at the surface of the particle, and the resulting image produced by an optical system.

Correspondence-free pose estimation for 3D objects from noisy depth data

Estimating the pose of objects from depth data is a problem of considerable practical importance for many vision applications. This paper presents an approach for accurate and efficient 3D pose estimation from noisy 2.5D depth images obtained from a consumer depth sensor. Initialized with a coarsely accurate pose, the proposed approach applies a hypothesize-and-test scheme that combines stochastic optimization and graphics-based rendering to refine the supplied initial pose, so that it accurately accounts for a sensed depth image. Pose refinement employs particle swarm optimization to minimize an objective function that quantifies the misalignment between the acquired depth image and a rendered one that is synthesized from a hypothesized pose with the aid of an object mesh model. No explicit correspondences between the depth data and the model need to be established, whereas pose hypothesis rendering and objective function evaluation are efficiently performed on the GPU. Extensive experimental results demonstrate the superior performance of the proposed approach compared to the ICP algorithm, which is typically used for pose refinement in depth images. Furthermore, the experiments indicate the graceful degradation of its performance to limited computational resources and its robustness to noisy and reduced polygon count models, attesting its suitability for use with automatically scanned object models and common graphics hardware.

Integrating Real-Time Fluid Simulation with a Voxel Engine

We present a method of adding sophisticated physical simulations to voxel-based games such as the hugely popular Minecraft (2012. http://minecraft.gamepedia.com/Liquid ), thus providing a dynamic and realistic fluid simulation in a voxel environment. An assessment of existing simulators and voxel engines is investigated, and an efficient real-time method to integrate optimized fluid simulations with voxel-based rasterisation on graphics hardware is demonstrated. We compare graphics processing unit (GPU) computer processing for a well-known incompressible fluid advection method with recent results on geometry shader-based voxel rendering. The rendering of visibility-culled voxels from fluid simulation results stored intermediately in CPU memory is compared with a novel, entirely GPU-resident algorithm.

The new SCIARA-fv3 numerical model and acceleration by GPGPU strategies

This paper presents the parallel implementation, using the Compute Unified Device Architecture (CUDA) architecture, of the SCIARA-fv3 Complex Cellular Automata model for simulating lava flows. The computational model is based on a Bingham-like rheology and both flow velocity and the physical time corresponding to a computational step have been made explicit. The parallelization design has involved, among other issues, the application of strategies that can avoid incorrect computation results due to race conditions and achieving the best performance and occupancy of the underlying available hardware. Two hardware types were adopted for testing different versions of the CUDA implementations of the SCIARA-fv3 model, namely the GTX 580 and GTX 680 graphic processors. Despite its computational complexity, carried out experiments of the model parallelization have shown significant performance improvements, confirming that graphic hardware can represent a valid solution for the implementation of Cellular Automata models.

Live intrinsic video

Intrinsic video decomposition refers to the fundamentally ambiguous task of separating a video stream into its constituent layers, in particular reflectance and shading layers. Such a decomposition is the basis for a variety of video manipulation applications, such as realistic recoloring or retexturing of objects. We present a novel variational approach to tackle this underconstrained inverse problem at real-time frame rates, which enables on-line processing of live video footage. The problem of finding the intrinsic decomposition is formulated as a mixed variational ℓ 2 - ℓ p -optimization problem based on an objective function that is specifically tailored for fast optimization. To this end, we propose a novel combination of sophisticated local spatial and global spatio-temporal priors resulting in temporally coherent decompositions at real-time frame rates without the need for explicit correspondence search. We tackle the resulting high-dimensional, non-convex optimization problem via a novel data-parallel iteratively reweighted least squares solver that runs on commodity graphics hardware. Real-time performance is obtained by combining a local-global solution strategy with hierarchical coarse-to-fine optimization. Compelling real-time augmented reality applications, such as recoloring, material editing and retexturing, are demonstrated in a live setup. Our qualitative and quantitative evaluation shows that we obtain high-quality real-time decompositions even for challenging sequences. Our method is able to outperform state-of-the-art approaches in terms of runtime and result quality -- even without user guidance such as scribbles.

Forward Light Cuts: A Scalable Approach to Real-Time Global Illumination

We present Forward Light Cuts, a novel approach to real-time global illumination using forward rendering techniques. We focus on unshadowed diffuse interactions for the first indirect light bounce in the context of large models such as the complex scenes usually encountered in CAD application scenarios. Our approach efficiently generates and uses a multiscale radiance cache by exploiting the geometry-specific stages of the graphics pipeline, namely the tessellator unit and the geometry shader To do so, we assimilate virtual point lights to the scene's triangles and design a stochastic decimation process chained with a partitioning strategy that accounts for both close-by strong light reflections, and distant regions from which numerous virtual point lights collectively contribute strongly to the end pixel. Our probabilistic solution is supported by a mathematical analysis and a number of experiments covering a wide range of application scenarios. As a result, our algorithm requires no precomputation of any kind, is compatible with dynamic view points, lighting condition, geometry and materials, and scales to tens of millions of polygons on current graphics hardware.