SCEA programmer Naty Hoffman pointed us to a useful technical report from researchers Michael Ashikhmin and Simon Premoze on bidirectional reflectance distribution function, a formalism often used for representing surface reflection properties in computer graphics. Titled Distribution-based BRDFs, the paper is now available online.

Ashikhmin and Premoze outline several characteristics desirable in a useful BRDF representation:

• represent a significant number of real-world materials with sufficient accuracy for visual applications;
• use measured data and allow acquisition of the necessary information for existing materials quickly and easily;
• be able to model new materials from scratch, i.e., not rely exclusively on measured data;
• respect basic physical properties of non-negativity, reciprocity and energy conservation;
• allow efficient sampling in a Monte-Carlo rendering system;
• allow straightforward hardware implementation;
• be compact;
• have at least a semi-intuitive interpretation and be simple to use for non-BRDF experts.

Though many BRDF models have been proposed, the report notes that most of those models do not have "at least some of the desirable practical properties." Distribution-based BRDFs aims to present a simple, flexible model satisfying many of the above requirements: ]"We show that the proposed model provides a good approximation for many real world materials, obeys basic physical restrictions, allows straightforward hardware implementation and provides for efficient sampling in a Monte-Carlo rendering system. A procedure to fit the model to BRDF measurement data is presented which suggests a simplified way of measuring surface reflection."

Posted by Eric Caoili at 05:53 AM | Permalink | Comments (0)

If you can't control your actions in a game, might the game be to blame? In this Intel-supported technical article originally published in Game Developer magazine, Neversoft co-founder Mick West examines the problem of response lag in games, along with a number of possible solutions.

Response lag can be described as "the delay between the player triggering an event and the player receiving feedback (usually visual) that the event has occurred." Whenever the delay is too long, the game feels unresponsive. It's easy to see how responsiveness can make or break a game at first impression.

According to West, if your game is unresponsive, it could be the result of cumulative effects of several different factors. "Adjusting one factor alone may not make a perceptible difference, but addressing all the factors can lead to a noticeable improvement."

Players, and sometimes even designers, cannot always put into words what feels wrong when a game is unresponsive, sometimes simply concluding that the game sucks, without really understanding why. West argues that "designers and programmers need to be aware of response lag and the negative effect it has on a game, even if test players do not directly report it as a factor."

Posted by Eric Caoili at 04:13 PM | Permalink | Comments (0)

In our featured video for the week, Intel Software Network blogger and engineering manager Scott Crabtree describes “Carry Small, Game Large,” a new gameplay model for mobile video games which promises a a big, shared multiplayer gaming experience.

Crabtree boasts that with the new model, players can "walk up with a laptop, a handheld, or any mobile computer that can browse the internet, connecting to a multiplayer game projected on a big screen." This way, everyone is playing together in the same place.

Some of the example games the engineer cites for this setup include a group jigsaw puzzle, a multiplayer tank game, and a poker game. He went on to explain the appeal of the gameplay model: "Typically people are at home, looking at their own private view of the world. [With] this way of playing, everyone comes together, and everyone can talk to each other as they're playing whatever game is up on the big screen. "

Posted by Eric Caoili at 02:26 PM | Permalink | Comments (0)

Delivering a technology futures speech in mid-June, Intel chief technology officer Justin Rattner stated that Intel's "aggressive multicore" approach trumps a graphics processor when the cores use ray tracing as opposed to rasterization, according to financial news site Forbes.com.

It's possible that this line of thinking could explain what the company has planned with all of the processor cores it has in its road map for future chips. Rattner affirmed, "Ray tracing is squarely in Intel's future."

A company spokesman added at a recent Intel research briefing that ray tracing goes hand-in-hand with parallel computing, as it is capable of scaling across thousands of cores. Rattner believes that graphics processors are "fundamentally tied" to the raster architecture.

AMD chief technology officer Raja Koduri, however, argued the opposite, that graphics processors are better for ray tracing over a general-purpose multicore processor, as it can be "tuned to the application." Koduri claims that multicore graphics processors, along with accelerator technology found in graphics subsystems, can also be used for ray tracing.

With a wide range of 3D modeling applications ideal for ray tracing, such as engineering and motion picture animation, it's in both companies' interest to produce the chips best suited for ray tracing. But it will be consumers who decide in the end which solution works best.

Posted by Eric Caoili at 04:54 AM | Permalink | Comments (26)