EGSR10: 21th Eurographics Symposium on Rendering

Permanent URI for this collection

https://diglib.eg.org/handle/10.2312/389

Browse

Now showing 1 - 20 of 29

A Dynamic Noise Primitive for Coherent Stylization
(The Eurographics Association and Blackwell Publishing Ltd, 2010) Benard, P.; Lagae, A.; Vangorp, P.; Lefebvre, S.; Drettakis, G.; Thollot, J.
We present a new solution for temporal coherence in non-photorealistic rendering (NPR) of animations. Given the conflicting goals of preserving the 2D aspect of the style and the 3D scene motion, any such solution is a tradeoff. We observe that primitive-based methods in NPR can be seen as texture-based methods when using large numbers of primitives, leading to our key insight, namely that this process is similar to sparse convolution noise in procedural texturing. Consequently, we present a new primitive for NPR based on Gabor noise, that preserves the 2D aspect of noise, conveys the 3D motion of the scene, and is temporally continuous. We can thus use standard techniques from procedural texturing to create various styles, which we show for interactive NPR applications. We also present a user study to evaluate this and existing solutions, and to provide more insight in the trade-off implied by temporal coherence. The results of the study indicate that maintaining coherent motion is important, but also that our new solution provides a good compromise between the 2D aspect of the style and 3D motion.
Patch-based Texture Interpolation
(The Eurographics Association and Blackwell Publishing Ltd, 2010) Ruiters, Roland; Schnabel, Ruwen; Klein, Reinhard
In this paper, we present a novel exemplar-based technique for the interpolation between two textures that combines patch-based and statistical approaches. Motivated by the notion of texture as a largely local phenomenon, we warp and blend small image neighborhoods prior to patch-based texture synthesis. In addition, interpolating and enforcing characteristic image statistics faithfully handles high frequency detail. We are able to create both intermediate textures as well as continuous transitions. In contrast to previous techniques computing a global morphing transformation on the entire input exemplar images, our localized and patch-based approach allows us to successfully interpolate between textures with considerable differences in feature topology for which no smooth global warping field exists.
Real-Time Concurrent Linked List Construction on the GPU
(The Eurographics Association and Blackwell Publishing Ltd, 2010) Yang, Jason C.; Hensley, Justin; Gruen, Holger; Thibieroz, Nicolas
We introduce a method to dynamically construct highly concurrent linked lists on modern graphics processors. Once constructed, these data structures can be used to implement a host of algorithms useful in creating complex rendering effects in real time. We present a straightforward way to create these linked lists using generic atomic operations available in APIs such as OpenGL 4.0 and DirectX 11. We also describe several possible applications of our algorithm. One example uses per-pixel linked lists for order-independent transparency; as a consequence, we are able to directly implement fully programmable blending, which frees developers from the restrictions imposed by current graphics APIs. The second uses linked lists to implement real-time indirect shadows.
Spectralization: Reconstructing spectra from sparse data
(The Eurographics Association and Blackwell Publishing Ltd, 2010) Rump, Martin; Klein, Reinhard
Traditional RGB reflectance and light data suffers from the problem of metamerism and is not suitable for rendering purposes where exact color reproduction under many different lighting conditions is needed. Nowadays many setups for cheap and fast acquisition of RGB or similar trichromatic datasets are available. In contrast to this, multi- or even hyper-spectral measurements require costly hardware and have severe limitations in many cases. In this paper, we present an approach to combine efficiently captured RGB data with spectral data that can be captured with small additional effort for example by scanning a single line of an image using a spectral line-scanner. Our algorithm can infer spectral reflectances and illumination from such sparse spectral and dense RGB data. Unlike other approaches, our method reaches acceptable perceptual errors with only three channels for the dense data and thus enables further use of highly efficient RGB capture systems. This way, we are able to provide an easier and cheaper way to capture spectral textures, BRDFs and environment maps for the use in spectral rendering systems.
SafeGI: Type Checking to Improve Correctness in Rendering System Implementation
(The Eurographics Association and Blackwell Publishing Ltd, 2010) Ou, Jiawei; Pellacini, Fabio
Historically, rendering system development has been mainly focused on improving the numerical accuracy of the rendering algorithms and their runtime efficiency. In this paper, we propose a method to improve the correctness not of the algorithms themselves, but of their implementation. Specifically, we show that by combining static type checking and generic programming, rendering system and shader development can take advantage of compile-time checking to perform dimensional analysis, i.e. to enforce the correctness of physical dimensions and units in light transport, and geometric space analysis, i.e. to ensure that geometric computations respect the spaces in which points, vectors and normals were defined. We demonstrate our methods by implementing a CPU path tracer and a GPU renderer which previews direct illumination. While we build on prior work to develop our implementations, the main contribution of our work is to show that dimensional analysis and geometric space checking can be successfully integrated into the development of rendering systems and shaders.
An Image-Based Approach for Stochastic Volumetric and Procedural Details
(The Eurographics Association and Blackwell Publishing Ltd, 2010) Gilet, G.; Dischler, J-M.
Noisy volumetric details like clouds, grounds, plaster, bark, roughcast, etc. are frequently encountered in nature and bring an important contribution to the realism of outdoor scenes. We introduce a new interactive approach, easing the creation of procedural representations of stochastic volumetric details by using a single example photograph. Instead of attempting to reconstruct an accurate geometric representation from the photograph, we use a stochastic multi-scale approach that fits parameters of a multi-layered noise-based 3D deformation model, using a multi-resolution filter banks error metric. Once computed, visually similar details can be applied to arbitrary objects with a high degree of visual realism, since lighting and parallax effects are naturally taken into account. Our approach is inspired by image-based techniques. In practice, the user supplies a photograph of an object covered by noisy details, provides a corresponding coarse approximation of the shape of this object as well as an estimated lighting condition (generally a light source direction). Our system then determines the corresponding noise-based representation as well as some diffuse, ambient, specular and semi-transparency reflectance parameters. The resulting details are fully procedural and, as such, have the advantage of extreme compactness, while they can be infinitely extended without repetition in order to cover huge surfaces.
Sparsely Precomputing The Light Transport Matrix for Real-Time Rendering
(The Eurographics Association and Blackwell Publishing Ltd, 2010) Huang, Fu-Chung; Ramamoorthi, Ravi
Precomputation-based methods have enabled real-time rendering with natural illumination, all-frequency shadows, and global illumination. However, a major bottleneck is the precomputation time, that can take hours to days. While the final real-time data structures are typically heavily compressed with clustered principal component analysis and/or wavelets, a full light transport matrix still needs to be precomputed for a synthetic scene, often by exhaustive sampling and raytracing. This is expensive and makes rapid prototyping of new scenes prohibitive. In this paper, we show that the precomputation can be made much more efficient by adaptive and sparse sampling of light transport. We first select a small subset of dense vertices , where we sample the angular dimensions more completely (but still adaptively). The remaining sparse vertices require only a few angular samples, isolating features of the light transport. They can then be interpolated from nearby dense vertices using locally low rank approximations. We demonstrate sparse sampling and precomputation 5 x faster than previous methods.
Fragment-Parallel Composite and Filter
(The Eurographics Association and Blackwell Publishing Ltd, 2010) Patney, Anjul; Tzeng, Stanley; Owens, John D.
We present a strategy for parallelizing the composite and filter operations suitable for an order-independent rendering pipeline implemented on a modern graphics processor. Conventionally, this task is parallelized across pixels/subpixels, but serialized along individual depth layers. However, our technique extends the domain of parallelization to individual fragments (samples), avoiding a serial dependence on the number of depth layers, which can be a constraint for scenes with high depth complexity. As a result, our technique scales with the number of fragments and can sustain a consistent and predictable throughput in scenes with both low and high depth complexity, including those with a high variability of depth complexity within a single frame. We demonstrate composite/filter performance in excess of 50M fragments/sec for scenes with more than 1500 semi-transparent layers.
Fragment-Parallel Composite and Filter
(The Eurographics Association and Blackwell Publishing Ltd, 2010)
Adaptive Volumetric Shadow Maps
(The Eurographics Association and Blackwell Publishing Ltd, 2010) Salvi, Marco; Vidimce, Kiril; Lauritzen, Andrew; Lefohn, Aaron
We introduce adaptive volumetric shadow maps (AVSM), a real-time shadow algorithm that supports high-quality shadowing from dynamic volumetric media such as hair and smoke. The key contribution of AVSM is the introduction of a streaming simplification algorithm that generates an accurate volumetric light attenuation function using a small fixed memory footprint. This compression strategy leads to high performance because the visibility data can remain in on-chip memory during simplification and can be efficiently sampled during rendering. We demonstrate that AVSM compression closely approximates the ground-truth correct solution and performs competitively to existing real-time rendering techniques while providing higher quality volumetric shadows.
On the Effective Dimension of Light Transport
(The Eurographics Association and Blackwell Publishing Ltd, 2010) Lessig, Christian; Fiume, Eugene
Light transport is often characterized within a high-dimensional space although practitioners have long known that it commonly behaves as a much lower-dimensional phenomenon. We study the effective dimension of light transport over a neighborhood on the scene manifold and show that under plausible assumptions the dimensionality is characterized by the spectrum of the spatio-spectral concentration problem. This allows us to improve existing estimates for the dimension in computer graphics using a more insightful derivation and for the first time we obtain optimal representations. The relevance of our results for existing rendering applications is discussed.
On Floating-Point Normal Vectors
(The Eurographics Association and Blackwell Publishing Ltd, 2010) Meyer, Quirin; Suessmuth, Jochen; Sussner, Gerd; Stamminger, Marc; Greiner, Guenther
In this paper we analyze normal vector representations. We derive the error of the most widely used representation, namely 3D floating-point normal vectors. Based on this analysis, we show that, in theory, the discretization error inherent to single precision floating-point normals can be achieved by 250.2 uniformly distributed normals, addressable by 51 bits. We review common sphere parameterizations and show that octahedron normal vectors perform best: they are fast and stable to compute, have a controllable error, and require only 1 bit more than the theoretical optimal discretization with the same error.
Two Methods for Fast Ray-Cast Ambient Occlusion
(The Eurographics Association and Blackwell Publishing Ltd, 2010) Laine, Samuli; Karras, Tero
Ambient occlusion has proven to be a useful tool for producing realistic images, both in offline rendering and interactive applications. In production rendering, ambient occlusion is typically computed by casting a large number of short shadow rays from each visible point, yielding unparalleled quality but long rendering times. Interactive applications typically use screen-space approximations which are fast but suffer from systematic errors due to missing information behind the nearest depth layer.In this paper, we present two efficient methods for calculating ambient occlusion so that the results match those produced by a ray tracer. The first method is targeted for rasterization-based engines, and it leverages the GPU graphics pipeline for finding occlusion relations between scene triangles and the visible points. The second method is a drop-in replacement for ambient occlusion computation in offline renderers, allowing the querying of ambient occlusion for any point in the scene. Both methods are based on the principle of simultaneously computing the result of all shadow rays for a single receiver point.
Interactive, Multiresolution Image-Space Rendering for Dynamic Area Lighting
(The Eurographics Association and Blackwell Publishing Ltd, 2010) Nichols, Greg; Penmatsa, Rajeev; Wyman, Chris
Area lights add tremendous realism, but rendering them interactively proves challenging. Integrating visibility is costly, even with current shadowing techniques, and existing methods frequently ignore illumination variations at unoccluded points due to changing radiance over the light s surface. We extend recent image-space work that reduces costs by gathering illumination in a multiresolution fashion, rendering varying frequencies at corresponding resolutions. To compute visibility, we eschew shadow maps and instead rely on a coarse screen-space voxelization, which effectively provides a cheap layered depth image for binary visibility queries via ray marching. Our technique requires no precomputation and runs at interactive rates, allowing scenes with large area lights, including dynamic content such as video screens.
A Layered Particle-Based Fluid Model for Real-Time Rendering of Water
(The Eurographics Association and Blackwell Publishing Ltd, 2010) Bagar, Florian; Scherzer, Daniel; Wimmer, Michael
We present a physically based real-time water simulation and rendering method that brings volumetric foam to the real-time domain, significantly increasing the realism of dynamic fluids. We do this by combining a particle-based fluid model that is capable of accounting for the formation of foam with a layered rendering approach that is able to account for the volumetric properties of water and foam. Foam formation is simulated through Weber number thresholding. For rendering, we approximate the resulting water and foam volumes by storing their respective boundary surfaces in depth maps. This allows us to calculate the attenuation of light rays that pass through these volumes very efficiently. We also introduce an adaptive curvature flow filter that produces consistent fluid surfaces from particles independent of the viewing distance.
Interactive Editing of Lighting and Materials using a Bivariate BRDF Representation
(The Eurographics Association and Blackwell Publishing Ltd, 2010) Sitthi-Amorn, Pitchaya; Romeiro, Fabiano; Zickler, Todd; Lawrence, Jason
We present a new Precomputed Radiance Transfer (PRT) algorithm based on a two dimensional representation of isotropic BRDFs. Our approach involves precomputing matrices that allow quickly mapping environment lighting, which is represented in the global coordinate system, and the surface BRDFs, which are represented in a bivariate domain, to the local hemisphere at a surface location where the reflection integral is evaluated. When the lighting and BRDFs are represented in a wavelet basis, these rotation matrices are sparse and can be efficiently stored and combined with pre-computed visibility at run-time. Compared to prior techniques that also precompute wavelet rotation matrices, our method allows full control over the lighting and materials due to the way the BRDF is represented. Furthermore, this bivariate parameterization preserves sharp specular peaks and grazing effects that are attenuated in conventional parameterizations. We demonstrate a prototype rendering system that achieves real-time framerates while lighting and materials are edited.
A PCA Decomposition for Real-time BRDF Editing and Relighting with Global Illumination
(The Eurographics Association and Blackwell Publishing Ltd, 2010) Nguyen, Chuong H.; Kyung, Min-Ho; Lee, Joo-Haeng; Nam, Seung-Woo
We propose a novel rendering method which supports interactive BRDF editing as well as relighting on a 3D scene. For interactive BRDF editing, we linearize an analytic BRDF model with basis BRDFs obtained from a principal component analysis. For each basis BRDF, the radiance transfer is precomputed and stored in vector form. In rendering time, illumination of a point is computed by multiplying the radiance transfer vectors of the basis BRDFs by the incoming radiance from gather samples and then linearly combining the results weighted by user-controlled parameters. To improve the level of accuracy, a set of sub-area samples associated with a gather sample refines the glossy reflection of the geometric details without increasing the precomputation time. We demonstrate this program with a number of examples to verify the real-time performance of relighting and BRDF editing on 3D scenes with complex lighting and geometry.
An Optimizing Compiler for Automatic Shader Bounding
(The Eurographics Association and Blackwell Publishing Ltd, 2010) Clarberg, Petrik; Toth, Robert; Hasselgren, Jon; Akenine-Moeller, Tomas
A New Ward BRDF Model with Bounded Albedo
(The Eurographics Association and Blackwell Publishing Ltd, 2010) Geisler-Moroder, David; Duer, Arne
Due to its realistic appearance, computational convenience, and efficient Monte Carlo sampling, Ward s anisotropic BRDF is widely used in computer graphics for modeling specular reflection. Incorporating the criticism that the Ward and the Ward-Duer model do not meet energy balance at grazing angles, we propose a modified BRDF that is energy conserving and preserves Helmholtz reciprocity. The new BRDF is computationally cheap to evaluate, admits efficient importance sampling, and thus sustains the main benefits of the Ward model. We show that the proposed BRDF is better suited for fitting measured reflectance data of a linoleum floor used in a real-world building than the Ward and the Ward-Duer model.
Visibility Editing For All-Frequency Shadow Design
(The Eurographics Association and Blackwell Publishing Ltd, 2010) Obert, Juraj; Pellacini, Fabio; Pattanaik, Sumanta
We present an approach for editing shadows in all-frequency lighting environments. To support artistic control, we propose to decouple shadowing from lighting and focus on providing intuitive controls to edit the former. To accomplish this task, we precompute and store scene visibility information separately from lighting and BRDFs and allow artists to edit visibility directly, by providing operations to select shadows and edit their shape. To facilitate a wider range of editing operations, we generalize visibility from binary to three-channel oating point quantities and introduce a novel shadow representation based on computation of visibility ratios between the original render and the edited one. We demonstrate our results for diffuse and glossy surfaces, still scenes and animations.

Browse

Browsing EGSR10: 21th Eurographics Symposium on Rendering by Issue Date

Results Per Page

Sort Options