This blog has moved! Please update your links

February 28, 2009 at 12:20 am (News)

This blog has moved! Please update your links!

My new website is and the levelofdetail blog is now located at

There’s a new post there about the first day of the I3D 2009 conference, so go there and read it. And update your RSS feeds!

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Let’s Have a Min/Max Party

December 11, 2008 at 5:54 am (News, Papers)

Today I was waiting for a session to begin at SIGGRAPH ASIA and began to think about how there are several cool papers that exploit min/max  images. A min/max image is an image pyramid that is sort of like a quadtree. The bottom level of the hierarchy is the original image while the elements in each subsequent level of the hierarchy contain the minimum and maximum of four elements in the previous level. So it’s sort of like a mip map, but instead of averaging values, you store the min and max of the previous level. This min/max hierarchy can be generated quickly in log n passes but can be used for making conservative estimations for large regions of your image. Refer to the following papers:

Maximum Mipmaps for Fast, Accurate, and Scalable Dynamic Height Field Rendering by A. Tevs, I. Ihrke, H.-P. Seidel

– Uses min/max maps to ray trace height fields. I feel like this idea has been around for ages but here it is all packaged up with a neat little bow.

Fast GPU Ray Tracing of Dynamic Meshes using Geometry Images by Nathan Carr, Jared Hoberock, Keenan Crane, John C. Hart.

– Uses min/max hierarchies of Geometry Images to accelerate the ray tracing of meshes.

Real-time Soft Shadow Mapping by Backprojection by Gaël Guennebaud, Loïc Barthe, Mathias Paulin
High-Quality Adaptive Soft Shadow Mapping by Gaël Guennebaud, Loïc Barthe, Mathias Paulin

–  I’ve ranted about these papers before. These works generate min/max hierarchies of shadow camera depth images to perform efficient blocker searches for soft shadow rendering, and also to determine penumbra regions for further optimization.

March of the Froblins SIGGRAPH course notes by Jeremy Shopf, Joshua Barczak, Christopher Oat, Natalya Tatarchuk

– Used a min/max hierarchy of the depth buffer to occlusion cull agents in our crowd simulation. Technically this only used the max portion of the hierarchy, but I didn’t want to title this Let’s have a Min/Max Party (Min is Optional).

Anyway, I think it’s kind of neat. I’m going to make another post tomorrow night about an awesome paper that’s here at the conference but I don’t want to write about it until I have a chance to clear up some nebulous parts of the paper with the author.

In other news, I received official word that the GDC lecture I proposed was accepted so I guess I will be seeing some of you in San Francisco next year in March. I’m excited about this talk because it came directly out of a post on this blog. Turns out this isn’t a waste of time after all!

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Fantasy Lab releases Radium SDK

August 26, 2008 at 12:00 pm (News)

Fantasy Lab, the game development studio started by Mike Bunnell (formerly of NVIDIA), has updated their website with information about their new real-time global illumination SDK called Radium. You’ll remember Fantasy Lab as the company that released the Rhinork GI demo and announced the game Danger Planet (covered here). The description boasts infinite bounces of light. Assuming that they are using the same disc-based transfer approached used in Bunnell’s GPU Gems 2 article (also check out the recent Pixar paper Point-Based Approximate Color Bleeding), I think this means that any number of bounces can be calculated as each bounce is an iteration in that algorithm. I’d definitely like to hear more details but I suppose that is unlikely to happen as they are trying to make a living 🙂

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Game Computing Applications Group @ SIGGRAPH

August 9, 2008 at 3:14 pm (News, Presentations) (, , , )

The group I work in at AMD is involved in a few presentations at SIGGRAPH this year. First, Chris Oat and Natalya Tatarchuk will be presenting a talk in the Advances in Real-Time Rendering in 3D Graphics and Games course on Monday on our latest demo “Froblins”. This talk will cover using the GPU and DirectX 10.1 for scene management, occlusion culling, terrain tessellation, approximations to global illumination, character tessellation, and crowd simulation.

I will be presenting a shorter talk on Thursday from 4:15-4:45 in the Beyond Programmable Shading: In Action course, focusing on how we used the GPU to do some general computing in the Froblins demo to allow our Froblin characters to navigate around the world and avoid each other. My addition to this course was a bit on short notice so I am fairly nervous, but how could I pass up an opportunity to speak at SIGGRAPH? I must say I am very jealous of my co-workers who will be done with all presenting duties on the first day of the conference!

I am always eager to meet new people so please feel free to introduce yourself if you will be in attendance!

Update: Here’s the link to the chapter from the course notes on our Froblins demo: March of the Froblins: Simulation and Rendering Massive Crowds of Intelligent and Detailed Creatures on GPU

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ATI HD 4870 and 4850

June 25, 2008 at 5:01 pm (News)

*Shameless home-team raving content below*

The NDA on the new ATI hardware (R770) was lifted today, so a boat-load of reviews are out. And they’re all glowing. I’ve been with the company for about a year and a half and NVIDIA has had us pinned down from the day I started until now. It’s nice to have a winning product out there. If you’re thinking about buying a mid-range graphics card ($199-$299), or you want help ensure that I have a job in the future,  now is the time.

Hexus (french)
computerbase (german)

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Blog’s Not Dead

June 20, 2007 at 2:28 pm (News, Papers)

I haven’t really put much up here recently, but this blog is not dead! I’m just busy at work and haven’t had a terrific amount of time to devote to pursuing solo interests. Please feel free to post good papers you’ve read recently in the comments.

On a side note, NPAR (Non-Photorealistic and Artistic Rendering) 2007 papers are posted.

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