Multi-layer dual-resolution screen-space ambient occlusion

Bavoil, Louis; Saínz, Miguel

doi:10.1145/1597990.1598035

Cited by 50 publications

(44 citation statements)

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“…Lower resolution (mipmapped) depth buffers can be used for sampling farther from the receiver as done by [Bavoil and Sainz 2009] [Hoang andLow 2012] [McGuire et al 2012]. An artefact-free sampling of this multi-resolution representation is not a trivial task, as shown in [Snyder and Nowrouzezahrai 2008].…”

Section: Previous Workmentioning

confidence: 99%

“…Because we in this paper advocate a high quality and physically correct SSAO, we find more promise in approaches that attempt to fill the missing scene geometry with real information of the scene instead of fitting a scene-dependent assumption. In previous work such information has been introduced in the form of multiple depth layers [Bavoil and Sainz 2009] and multiple views [Vardis et al 2013]. Extending our method into that direction is left as future work.…”

Section: Limitations Of Depth Buffer Geometrymentioning

confidence: 99%

“…We are also investigating the possibility of extending our method to handle multiple depth layers [Bavoil and Sainz 2009] or multiple views [Vardis et al 2013] which-when coupled with sufficiently large guard bands-would alleviate the screen-space problem of missing scene geometry. This could allow our method to produce results comparable to global ray tracing.…”

Section: Future Workmentioning

confidence: 99%

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Screen-space far-field ambient obscurance

Timonen

2013

Proceedings of the 5th High-Performance Graphics Conference

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Figure 1: Left: screen-space far-field (≥ 15 px) occlusion component solved by our method in 4.6 ms on a 1280(+256)×720(+144) depth buffer. Right: ray traced screen-space reference result. AbstractAmbient obscurance (AO) is an effective approximation of global illumination, and its screen-space (SSAO) versions that operate on depth buffers only are widely used in real-time applications. We present an SSAO method that allows the obscurance effect to be determined from the entire depth buffer for each pixel. Our contribution is two-fold: Firstly, we build an obscurance estimator that accurately converges to ray traced reference results on the same screenspace geometry. Secondly, we generate an intermediate representation of the depth field which, when sampled, gives local peaks of the geometry from the point of view of the receiver. Only a small number of such samples are required to capture AO effects without undersampling artefacts that plague previous methods. Our method is unaffected by the radius of the AO effect or by the complexity of the falloff function and produces results within a few percent of a ray traced screen-space reference at constant real-time frame rates.

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Section: Previous Workmentioning

confidence: 99%

Section: Limitations Of Depth Buffer Geometrymentioning

confidence: 99%

Section: Future Workmentioning

confidence: 99%

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Screen-space far-field ambient obscurance

Timonen

2013

Proceedings of the 5th High-Performance Graphics Conference

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“…Introduced by Zhukov et al [1998] as one part of ambient obscurance, AO has been extensively researched for use in dynamic environments with static models. The approaches can be divided into screen-space methods [Mittring 2007;Bavoil et al 2008;Kajalin 2009;Bavoil and Sainz 2009] or world-space methods [Kontkanen and Laine 2005;McGuire 2010;Loos and Sloan 2010].…”

Section: Ambient Occlusionmentioning

confidence: 99%

GPU curvature estimation on deformable meshes

Griffin

Wang

Berrios

et al. 2011

Symposium on Interactive 3D Graphics and Games

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Figure 1: On the left is one frame of an elephant animation visualizing estimated curvature. Blue indicates concave areas, red indicates convex areas, and green indicates saddle-shape areas. The middle is using surface curvature to approximate ambient occlusion. On the right is an orange volume with ∼1.5 billion vertices with Lambertian shading and ambient occlusion which we estimate curvature on in 39.3 ms. AbstractSurface curvature is used in a number of areas in computer graphics, including texture synthesis and shape representation, mesh simplification, surface modeling, and non-photorealistic line drawing. Most real-time applications must estimate curvature on a triangular mesh. This estimation has been limited to CPU algorithms, forcing object geometry to reside in main memory. However, as more computational work is done directly on the GPU, it is increasingly common for object geometry to exist only in GPU memory. Examples include vertex skinned animations and isosurfaces from GPU-based surface reconstruction algorithms.For static models, curvature can be pre-computed and CPU algorithms are a reasonable choice. For deforming models where the geometry only resides on the GPU, transferring the deformed mesh back to the CPU limits performance. We introduce a GPU algorithm for estimating curvature in real-time on arbitrary triangular meshes. We demonstrate our algorithm with curvature-based NPR feature lines and a curvature-based approximation for ambient occlusion. We show curvature computation on volumetric datasets with a GPU isosurface extraction algorithm and vertex-skinned animations. Our curvature estimation is up to ∼18x faster than a multithreaded CPU benchmark.

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“…Ray tracing methods are the gold standard for quality, but take minutes to evaluate. Recent screen space methods (e.g., [Mittring 2007;Kajalin 2009;Bavoil and Sainz 2009;Szirmay-Kalos et al 2009]) are well suited to console games because they execute in only a few milliseconds at HD resolution. However, they sacrifice significant quality for that performance and do not improve under the higher sample rates possible on today's GPUs.…”

mentioning

confidence: 99%

Ambient occlusion volumes

McGuire

2010

Proceedings of the 2010 ACM SIGGRAPH Symposium on Interactive 3D Graphics and Games

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Kajalin 2009] [Szirmay-Kalos et al. 2009] Ray Traced Reference Ambient Occlusion Volumes 256 samples/pix 64 samples/pix 5000 samples/pix (analytic) 16 ms 61 ms 556228 ms 31 ms Figure 1: 1.4 M-triangle scene at 720p resolution on GeForce 280 GT using geometry from Marvel Ultimate Alliance 2 by Vicarious Visions/Activision. The new Ambient Occlusion Volume algorithm produces quality comparable to ray tracing, in real time and with no noise. In contrast, many alternative screen-space algorithms offer extremely fast AO approximations but cannot converge towards the correct result, even when extended to high sampling rates as shown here.Introduction Ambient illumination is an approximation to the light reflected from the sky and other objects in a scene. Ambient occlusion (AO) is the darkening that occurs when this illumination is locally blocked by another object or a nearby fold in a surface. Both ambient illumination and occlusion are qualitatively important to perception of shape and depth in the real world. Artists have long recognized AO, and specifically seek to reproduce the real phenomena such as corner darkening and contact shadows. Because AO is so important to shape perception, practitioners in many disciplines rely software that simulates AO to visualize structures. Ambientocclusion renderings of building facades, medical data, and engineering parts reveal the spatial relationship between complex details. CG artists also a prefer untextured, AO-only rendering as a method for visualizing geometry. While the problem of computing an explicit AO factor has been studied for over a decade, most previous AO algorithms seek extreme quality or extreme performance. Ray tracing methods are the gold standard for quality, but take minutes to evaluate. Recent screen space methods (e.g., [Mittring 2007;Kajalin 2009;Bavoil and Sainz 2009;Szirmay-Kalos et al. 2009]) are well suited to console games because they execute in only a few milliseconds at HD resolution. However, they sacrifice significant quality for that performance and do not improve under the higher sample rates possible on today's GPUs. We build on the screen space notion of AO as a deferred shading pass for performance, but develop and analytic solution inspired by radiosity and Crow's shadow volumes and thus yields higher quality. By enabling high-quality AO in real-time, it is well suited to modeling applications and CAD. With screen-space subsampling it can match the performance of screen space methods with high quality for games on contemporary GPUs.

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Multi-layer dual-resolution screen-space ambient occlusion

Cited by 50 publications

References 3 publications

Screen-space far-field ambient obscurance

Screen-space far-field ambient obscurance

GPU curvature estimation on deformable meshes

Ambient occlusion volumes

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