Ray Tracing and Gaming – One Year Later

Source: PC Perspective Ray Tracing and Gaming – One Year Later
In case some of you guys aren’t checking out the RSS feeds of our articles or just skip over the icons above, I really need to make sure you see the new ray tracing article from Daniel Pohl.  As a follow up to Daniel’s previous article that first introduced ray tracing to our readers, this newest iteration dives into some examples of how ray tracing can be more efficient than rasterization when it come to rendering games. 

There are lots of examples, diagrams and explanations for all levels of reader ray tracing experience, and even a video to demonstrate how ray tracing could affect game play.  Be sure to check it out!

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Artistic representation of a building with 4 levels with each 4 rooms

When ray tracing, we want to figure out whether a piece of geometry is hit or not. In ray tracing speak we talk about a “camera” and when we shoot rays through it to determine what is visible we refer to these as “eye rays” or “primary rays”. Naively, we could just shoot eye rays everywhere and see what gets hit and what does not. Clearly, in the above example 15/16 of these rays would be wasted. Thinking about this situation a little, it seems obvious that it is very unlikely that the camera will “see” anything in the right-most room on the lowest-level, so why even bother checking if a ray hits any of the geometry from that area?

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Ray Tracing and Gaming – One Year Later

Manufacturer: Intel Ray Tracing and Gaming – One Year Later
Progress
After my last article about ray tracing and gaming hit the web I did some more research on scaling of ray tracing with the number of CPU cores. In order to simulate a 16-core machine I took four quad-core PCs and connected them over a Gigabit-Ethernet to combine their power. Because my project used the ray tracing library OpenRT from Saarland University which supports distributed rendering, this was quite easy to achieve.

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Performance scaling of ray tracing with different number of cores

The results were amazing: If you use a 16-core machine instead of a single-core machine then the frame rate increases by a factor of 15.2!

After all the attention the previous ray tracing article got around the world I was contacted by several companies interested in this technology. One of them was Intel. They told me they would have a real-time ray tracer that would be around 10× faster than everything else that has been published so far. These performance numbers were already written down in some research papers, but I did not trust them without seeing it myself. So I went over to Santa Clara to get a live demonstration of it.

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Then I saw it trace,   
now I’m a believer!
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So now I am a full-time research scientist working for Intel on ray tracing. As it turns out, Intel’s labs are very interested ray tracing because it is so well suited to general purpose CPUs. Our ray tracing research is just a part of an overall program here called “tera-scale computing” aimed at scaling CPUs from a few cores to many (meaning tens or hundreds).
 
Joining Intel also gave me the chance to demonstrate Quake 4: Ray-Traced with the new Intel ray tracer on several occasions such as the Games Convention 2007 in Leipzig and Intel Developer Forum  Fall 2007 in San Francisco. At the latter event it was even featured in the keynote from Justin Rattner (Intel CTO) about virtual worlds.

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At HD resolution we were able to achieve a frame rate of about 90 frames per second on a Dual-X5365 machine, utilizing all 8 cores of that system for rendering.

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More details about the presentation at Fall IDF 2007 can be found in Ryan Shrout’s article at PC Perspective.

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