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This video was published by Eurogamer‘s Digital Foundry department about two weeks ago; it shows footage captured from various games in the Gran Turismo series. What is remarkable about this video is that the same cars and tracks are shown on the original Playstation, the PSP, the Playstation 2 and Playstation 3. Since the developer (Polyphony Digital) has a reputation for squeezing the best visuals out of Sony’s platforms, this promises a rare “apples-to-apples” comparison across multiple hardware generations.

To my eyes, the display resolution changes drown out the more subtle differences in modeling, shading and lighting; it is also apparent to me that Polyphony no longer sits on the graphics throne in this generation. Other first-party PS3 titles such as Uncharted 2 and God of War III look better, in my opinion. The shadows are a particular weak spot: in places their resolution seems no higher than on the original Playstation!

More information on how the video was captured (as well as high-quality download links) can be found in Digital Foundry’s blog post.

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High-Performance Graphics, although a relatively new conference in its current form, has had a large impact on the field; it is the venue of choice for breaking research on new antialiasing techniques, micropolygon rendering, and novel uses of GPUs for graphics. HPG 2011 will be co-located with SIGGRAPH 2011 in Vancouver, and is looking for paper, presentation, and poster submissions. The full CFP is included after the break:

Read the rest of this entry »

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Although GPU Pro 2 isn’t even out yet, Wolfgang has started the call for articles for the next book in the series. The first GPU Pro was very good (even better in my opinion than the ShaderX series which preceded it), and the second book in the series (judging from its table of contents) seems likely to be strong as well.

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I received this CfP a week ago, but I was traveling so hadn’t had the time to post it earlier. I3D has always been a very good conference, with a high percentage of usable real-time rendering papers. This year’s conference was especially strong. Five of the papers were by people who had implemented the described techniques in commercial games (Crysis 2, Batman: Arkham Asylum, Civilization V, Toy Story 3 The Video Game, and Dark Void), and many of the other papers were also interesting and relevant (all papers are linked from Ke-Sen’s website).

Now is the opportunity to submit papers for I3D 2011, which will take place in San Francisco in late February. The full Call follows:

I3D 2011 Call for Participation

Submission System is now open!

Paper submission deadline: October 22, 2010

Conference info: http://www.i3dsymposium.org

Submission system: http://precisionconference.com/~i3d

Conference Date: February 18th – 20th, 2011

Location: Marriott Fisherman’s Wharf, San Francisco, CA

I3D is the leading-edge conference for real-time 3D computer graphics and human interaction, and 2011 marks the 25th year since the first conference gathering. We invite you to submit papers, posters, and interactive demos across the entire range of topics in interaction, interactive 3D graphics, and games. The fall deadline provides the perfect outlet for your summer work.

Topics include, but are not limited to:

  • Interaction devices and techniques
  • 3D game techniques
  • Interactive modeling
  • Level-of-detail approaches
  • Pre-computed lighting
  • Visibility computation
  • Real-time surface shading
  • Fast shadows, caustics and reflections
  • Imposters and image-based techniques
  • Animated models
  • GPU techniques
  • Navigation methods
  • Interactive visualization
  • Virtual and augmented reality
  • User studies of interactive techniques and applications

Paper submissions should be up to 8 pages in length and adhere to ACM SIGGRAPH style guidelines. The submission of a video to accompany the paper is encouraged. Papers will be peer-reviewed in a single-blind process and authors notified by e-mail.

Please visit the conference website at http://www.i3dsymposium.org for additional information, submission details, and further updates.

Send questions to:

  • general (at) i3dsymposium.org (for general inquiries)
  • papers (at) i3dsymposium.org (for questions on paper submission)
  • posters (at) i3dsymposium.org (for questions on posters & demos)

Important Dates:

  • Paper submissions due: October 22nd, 2010
  • Poster and demo submissions due: December 17th, 2010
  • Paper notifications: Dec 3, 2010
  • Poster and demo notifications: Jan 7, 2011
  • Conference: February 18th – 20th, 2011

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The SIGGRAPH Course “Advances in Real-Time Rendering for 3D Graphics and Games” has been held since 2006 with a consistently high level of quality. However the hosting of the materials is scattered around a few different websites, and the older years suffer from broken links and other issues. We are happy to host the course’s new home on a subdomain of this site: http://advances.realtimerendering.com/. At the moment only the SIGGRAPH 2010 course materials are present, but previous years will go up shortly.

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I3D 2011

The website for I3D 2011 is now up, including the time/place and CFP. I3D will be in San Francisco next year, from February 18-20th. I3D probably has a higher percentage of graphics papers relevant to games than any other conference; this year five of the papers described techniques already in use in games (including high-profile titles like Batman: Arkham Asylum and Civilization 5), and many of the other papers were also highly relevant. Unfortunately, very few game developers attend; I hope next year’s location (San Francisco is home to a large number of developers) will help.

I3D is a great small conference to publish real-time rendering papers. One advantage it has for authors over Eurographics conferences like EGSR, and co-sponsored conferences like HPG and SCA (in “Europe” years) is that it is not subject to Eurographics’ monumentally stupid “authors can’t post copies of their papers for a year after the conference” policy. This policy, of course, hurts the chance of your paper being cited by making it harder for people to read it – brilliant! Hopefully EG will see the error of its ways soon – until then, you are better off sending your papers to non-EG conferences like I3D.

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With less than two weeks until the conference, here’s my final pre-SIGGRAPH roundup of all the game development and real-time rendering content. This is to either to help convince people who are still on the fence about attending (unlikely at this late date) or to help people who are trying to decide which sessions to go to (more likely). If you won’t be able to attend SIGGRAPH this year, this might at least help you figure out which slides, videos, and papers to hunt for after the conference.

First of all, the SIGGRAPH online scheduler is invaluable for helping to sort out all the overlapping sessions (even if you just “download” the results into Eric’s lower-tech version). The iPhone app may show up before the conference, but given the vagaries of iTunes app store approval, I wouldn’t hold my breath.

The second resource is the Games Focus page, which summarizes the relevant content for game developers in one handy place. It makes a good starting point for building your schedule; the rest of this post goes into additional detail.

My previous posts about the panels and the talks, and several posts about the courses go into more detail on the content available in these programs.

Exhibitor Tech Talks are sponsored talks by various vendors, and are often quite good. Although the Games Focus page links to the Exhibitor Tech Talk page, for some reason that page has is no information about the AMD and NVIDIA tech talks (the Intel talk on Inspecting Complex Graphics Scenes in a Direct X Pipeline, about their Graphics Performance Analyzer tool, could be interesting). NVIDIA does have all the details on their tech talks at their SIGGRAPH 2010 page; the ones on OpenGL 4.0 for 2010, Parallel Nsight: GPU Computing and Graphics Development in Visual Studio, and Rapid GPU Ray Tracing Development with NVIDIA OptiX look particularly relevant. AMD has no such information available anywhere: FAIL.

One program not mentioned in the Games Focus page is a new one for this year: SIGGRAPH Dailies! where artists show a specific piece of artwork (animation, cutscene sequence, model, lighting setup, etc.) and discuss it for two minutes. This is a great program, giving artists a unique place to showcase the many bits of excellence that go into any good film or game. Although no game pieces got in this year, the show order includes great work from films such as Toy Story 3, Tangled, Percy Jackson, A Christmas Carol, The Princess and The Frog, Ratatouille, and Up. The show is repeated on Tuesday and Wednesday overlapping the Electronic Theater (which also should not be missed; note that it is shown on Monday evening as well).

One of my favorite things about SIGGRAPH is the opportunity for film and game people to talk to each other. As the Game-Film Synergy Chair, my primary responsibility was to promote content of interest to both. This year there are four such courses (two of which I am organizing and speaking in myself): Global Illumination Across Industries, Color Enhancement and Rendering in Film and Game Production, Physically Based Shading Models in Film and Game Production, and Beyond Programmable Shading I & II.

Besides the content specifically designed to appeal to both industries, a lot of the “pure film” content is also interesting to game developers. The Games Focus page describes one example (the precomputed SH occlusion used in Avatar), and hints at a lot more. But which?

My picks for “film production content most likely to be relevant to game developers”: the course Importance Sampling for Production Rendering, the talk sessions Avatar in Depth, Rendering Intangibles, All About Avatar, and Pipelines and Asset Management, the CAF production sessions Alice in Wonderland: Down the Rabbit Hole, Animation Blockbuster Breakdown, Iron Man 2: Bringing in the “Big Gun”, Making “Avatar”, The Making of TRON: LEGACY, and The Visual Style of How To Train Your Dragon, and the technical papers PantaRay: Fast Ray-Traced Occlusion Caching, An Artist-Friendly Hair Shading System, and Smoothed Local Histogram Filters. (unlike much of the other film production content, paper presentation videos are always recorded, so if a paper presentation conflicts with something else you can safely skip it).

Interesting, but more forward-looking film production stuff (volumetric effects and simulations that aren’t feasible for games now but might be in future): the course Volumetric Methods in Visual Effects, the talk sessions Elemental Training 101, Volumes and Precipitation, Simulation in Production, and Blowing $h!t Up, and the CAF production session The Last Airbender: Harnessing the Elements: Earth, Air, Water, and Fire.

Speaking of forward-looking content, SIGGRAPH papers written by academics (as opposed to film professionals) tend to fall in this category (in the best case; many of them are dead ends). I haven’t had time to look at the huge list of research papers in detail; I highly recommend attending the Technical Papers Fast-Forward to see which papers are worth paying closer attention to (it’s also pretty entertaining).

Some other random SIGGRAPH bits:

  • Posters are of very mixed quality (they have the lowest acceptance bar of any SIGGRAPH content) but quickly skimming them doesn’t take much time, and there is sometimes good stuff there. During lunchtime on Tuesday and Wednesday, the poster authors are available to discuss their work, so if you see anything interesting you might want to come back then and ask some questions.
  • The Studio includes several workshops and presentations of interest, particularly for artists.
  • The Research Challenge has an interesting interactive haunted house concept (Virtual Flashlight for Real-Time Scene Illumination and Discovery) presented by the Square Enix Research and Development Division.
  • The Geek Bar is a good place to relax and watch streaming video of the various SIGGRAPH programs.
  • The SIGGRAPH Reception, the Chapters Party, and various other social events throughout the week are great opportunities to meet, network, and talk graphics with lots of interesting and talented people from outside your regular circle of colleagues.

I will conclude with the list of game studios presenting at SIGGRAPH this year: Activision Studio Central, Avalanche Software, Bizarre Creations, Black Rock Studio, Bungie, Crytek, DICE, Disney Interactive Research, EDEN GAMES, Fantasy Lab, Gearbox, LucasArts, Naughty Dog, Quel Solaar, tri-Ace, SCE Santa Monica Studio, Square Enix R&D, Uber Entertainment, Ubisoft Montreal, United Front Games, Valve, and Volition. I hope for an even longer list in 2011!

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Try it – it’s a blast (keep hitting “refresh” to see new titles). Here’s a few that I got:

  • Bidirectional Rendering of Caustics for Light Fields
  • Reflective Normal-mapped Light Fields
  • Rendering of Inverse Geometry
  • Texturing of Multi-resolution Geometry using Polygonal Approximation
  • Displacement Mapping of Reflective Geometry for Surfaces

Can’t tell them from the real paper titles…

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After my last SIGGRAPH post, I spent a little more time digging around in the SIGGRAPH online scheduler, and found some more interesting details:

Global Illumination Across Industries

This is another film-game crossover course. It starts with a 15-minute introduction to global illumination by Jaroslav Křivánek, a leading researcher in efficient GI algorithms. It continues with six 25-30 minutes talks:

  • Ray Tracing Solution for Film Production Rendering, by Marcos Fajardo, Solid Angle. Marcos created the Arnold raytracer which was adopted by Sony Pictures Imageworks for all of their production rendering (including CG animation features like Cloudy with a Chance of Meatballs and VFX for films like 2012 and Alice in Wonderland). This is unusual in film production; most VFX and animation houses  use rasterization renderers like Renderman.
  • Point-Based Global Illumination for Film Production, by Per Christensen, Pixar. Per won a Sci-Tech Oscar for this technique, which is widely used in film production.
  • Ray Tracing vs. Point-Based GI for Animated Films, by Eric Tabellion, PDI/Dreamworks. Eric worked on the global illumination (GI) solution which Dreamworks used in Shrek 2; it will be interesting to hear what he has to say on the differences between the two leading film production GI techniques.
  • Adding Real-Time Point-based GI to a Video Game, Michael Bunnell, Fantasy Lab. Mike was also awarded the Oscar for the point-based technique (Christophe Hery was the third winner). He actually originated it as a real-time technique while working at NVIDIA; while Per and Christophe developed it for film rendering, Mike founded Fantasy Lab to further develop the technique for use in games.
  • Pre-computing Lighting in Games, David Larsson, Illuminate Labs. Illuminate Labs make very good prelighting tools for games; I used their Turtle plugin for Maya when working on God of War III and was impressed with its speed, quality and robustness.
  • Dynamic Global Illumination for Games: From Idea to Production, Anton Kaplanyan, Crytek. Anton developed the cascaded light propagation volume technique used in CryEngine 3 for dynamic GI; the I3D 2010 paper describing the technique can be found on Crytek’s publication page.

The course concludes with a 5 minute Q&A session with all speakers.

An Introduction to 3D Spatial Interaction With Videogame Motion Controllers

This course is presented by Joseph LaViola (director of the University of Central Florida Interactive Systems and User Experience Lab) and Richard Marks from Sony Computer Entertainment (principal inventor of the Eyetoy, Playstation Eye, and Playstation Move). Richard Marks gives two 45-minute talks, one on 3D Interfaces With 2D and 3D Cameras and one on 3D Spatial Interaction with the PlayStation Move. Prof. LaViola discusses Common Tasks in 3D User Interfaces, Working With the Nintendo Wiimote, and 3D Gesture Recognition Techniques.

Recent Advances in Real-Time Collision and Proximity Computations for Games and Simulations

After an introduction to the topic of collision detection and proximity queries, this course goes over recent research in collision detection for games including articulated, deformable and fracturing models. It concludes with optimization-oriented talks such as GPU-Based Proximity Computations (presented by Dinesh Manocha, University of North Carolina at Chapel Hill, one of the most prominent researchers in the area of collision detection), Optimizing Proximity Queries for CPU, SPU and GPU (presented by Erwin Coumans, Sony Computer Entertainment US R&D, primary author of the Bullet physics library, which is widely used for both games and feature films), and PhysX and Proximity Queries (presented by Richard Tonge, NVIDIA, one of the architects of the AGEIA  physics processing unit – the company was bought by NVIDIA and their software library formed the basis of the GPU-accelerated PhysX library).

Advanced Techniques in Real-Time Hair Rendering and Simulation

This course is presented by Cem Yuksel (Texas A&M University) and Sarah Tariq (NVIDIA). Between them, they have done a lot of the recent research on efficient rendering and simulation of hair. The course covers all aspects of real-time hair rendering: data management, the rendering pipeline, transparency, antialiasing, shading, shadows, and multiple scattering. It concludes with a discussion of real-time dynamic simulation of hair.

Ray Tracing Solution for Film Production Rendering
Fajardo

2:40 pm
Point-Based Global Illumination for Film Production
Christensen

3:05 pm
Ray Tracing vs. Point-Based GI for Animated Films
Tabellion

3:30 pm
Break 

3:45 pm
Adding Real-Time Point-based GI to a Video Game
Bunnell

4:15 pm
Pre-computing Lighting in Games
Larsson

4:45 pm
Dynamic Global Illumination for Games: From Idea to Production Kaplanyan

5:10 pm
Conclusions, Q & A
Ray Tracing Solution for Film Production Rendering

Fajardo

2:40 pm

Point-Based Global Illumination for Film Production

Christensen

3:05 pm

Ray Tracing vs. Point-Based GI for Animated Films

Tabellion

3:30 pm

Break

3:45 pm

Adding Real-Time Point-based GI to a Video Game

Bunnell

4:15 pm

Pre-computing Lighting in Games

Larsson

4:45 pm

Dynamic Global Illumination for Games: From Idea to Production Kaplanyan

5:10 pm

Conclusions, Q & A

All

All

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In my recent post about Gamefest 2010, I discussed Stephen Hill’s great presentation on the rendering techniques used in Splinter Cell: Conviction.

Since then, Stephen contacted me – it turns out I got some details wrong, and he also provided me with some additional details about the techniques in his talk. I will give the corrections and additional details here.

  1. What I described in the post as a “software hierarchical Z-Buffer occlusion system” actually runs completely on the GPU. It was directly inspired by the GPU occlusion system used in ATI’s “March of the Froblins” demo (described here), and indirectly by the original (1993) hierarchical z-buffer paper. Stephen describes his original contribution as “mostly scaling it up to lots of objects on DX9 hardware, piggy-backing other work and the 2-pass shadow culling”. Stephen promises more details on this “in a book chapter and possibly… a blog post or two” – I look forward to it.
  2. The rigid body AO volumes were initially inspired by the Ambient Occlusion Fields paper, but the closest research is an INRIA tech report that was developed in parallel with Stephen’s work (though he did borrow some ideas from it afterwards).
  3. The character occlusion was not performed using capsules, but via nonuniformly-scaled spheres. I’ll let Stephen speak to the details: “we transform the receiver point into ‘ellipsoid’-local space, scale the axes and lookup into a 1D texture (using distance to centre) to get the zonal harmonics for a unit sphere, which are then used to scale the direction vector. This works very well in practice due to the softness of the occlusion. It’s also pretty similar to Hardware Accelerated Ambient Occlusion Techniques on GPUs although they work purely with spheres, which may simplify some things. I checked the P4 history, and our implementation was before their publication, so I’m not sure if there was any direct inspiration. I’m pretty sure our initial version also predated Real-time Soft Shadows in Dynamic Scenes using Spherical Harmonic Exponentiation since I remember attending SIGGRAPH that year and teasing a friend about the fact that we had something really simple.”
  4. My statement that the downsampled AO buffer is applied to the frame using cross-bilateral upsampling was incorrect. Stephen just takes the most representative sample by comparing the full-resolution depth and object IDs against the surrounding down-sampled values. This is a kind of “bilateral point-sampling” which apparently works surprisingly well in practice, and is significantly cheaper than a full bilateral upsample. Interestingly, Stephen did try a more complex filter at one point: “Near the end I did try performing a bilinearly-interpolated lookup for pixels with a matching ID and nearby depth but there were failure cases, so I dropped it due to lack of time. I will certainly be looking at performing more sophisticated upsampling or simply increasing the resolution (as some optimisations near the end paid off) next time around.”

A recent blog post on Jeremy Shopf’s excellent Level of Detail blog mentions similarities between the sphere technique and one used for AMD’s ping-pong demo (the technique is described in the article Deferred Occlusion from Analytic Surfaces in ShaderX7). To me, the basic technique is reminiscent of Inigo Quilez‘ article on analytical sphere ambient occlusion; an HPG 2010 paper by Morgan McGuire does something similar with triangles instead of spheres.

Although the technique builds upon previous ones, it does add several new elements, and works well in the game. The technique does suffer from multiple-occlusion; I wonder if a technique similar to the 1D “compensation map’ used by Morgan McGuire might help.

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