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Supercomputing

Gigapixel Tapestries & Gigadecimal Pi 215

Posted by Hemos
from the welcome-to-the-machine dept.
RobotWisdom writes "The new New Yorker magazine has posted two long non-technical articles about the Chudnovsky brothers and their homebrew supercomputers. One is a 1992 article about how they calculated pi to over two billion decimal places using a $70,000 cluster with 16 nodes. The other is a brandnew piece about how they spent months creating a seamless multi-gigabyte image of a fifteenth century tapestry for New York's Metropolitan Museum of Art. Tapestries are essentially pixel-art on a non-rigid (cloth) matrix, so the manual labor of photographing it inch by inch had introduced many tiny deformations in the images, which they had to mathematically iron out. Old lo-res pix of the tapestries are on the Met's site, pix of the brothers are in the world brain."
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Gigapixel Tapestries & Gigadecimal Pi

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  • by Anonymous Coward on Monday April 04, 2005 @11:00AM (#12133845)
    Why do we need anything more than the low-res picture that they already have? Going super-high-res simply magnifies the imperfections. Art isn't meant to be enjoyed with your face pressed up against it.

    This has got to be one of the most short sighted posting on /., EVER. Or a clever troll. Art wasn't meant to enjoy from 40 feet away either (well actually some art is, but not in this case). Just like with movies/photos/music, it's always better to have the highest quality original and you can always downgrade for mass copies. Imagine if something were to happen to the tapestry itself, without a very high quality scan, you'd be screwed.
  • by leoval (827218) on Monday April 04, 2005 @11:23AM (#12134048)

    I disagree with your analogy. Aerial mosaics have nothing to do with the work that the brothers had to accomplish.

    For instance, in aerial photagraphy the landscape being photagraphed changes very little if it changes at all (most of the changes are not even perceptible at the resolution of the cameras). Therefore reconstructing the full image is pretty much trivial (finding the overlapping sections is straightforward).

    In this case, and from TA, the images changed from frame to frame! because of several factors, temperature, humidity, light conditions etc. Also the paper cover that the photographers used also disturbed the fine threading in the images. So determining the overlapping sections between tiles could not be easyly automated, in fact from the article it seems that they were not even discernible with the naked eye.

    I thing that the time spent in that project was actually productive, and that in the process a bunch of original algorithms were created (I hope they are published in some place).

  • Re:Pi Accuracy (Score:5, Insightful)

    by mikeplokta (223052) on Monday April 04, 2005 @11:43AM (#12134226)
    Pi's definition is mathematical, not physical. No one really knows the exact ratio between the circumference of a circle and its diameter, but it definitely varies depending on how curved space-time is in the vicinity of the circle, and on the size of the circle.

    Pi is 4 x (1 - 1/3 + 1/5 - 1/7 + 1/9 + 1/11 ...). (Or the limit of that series as its length tends to infinity, for the mathematical formalists among you.) Your accuracy in computing pi depends on how many terms of the series you can calculate (actually, there are alternative formulations that converge much more rapidly, but are less easy to write down in ASCII.)
  • by Adult film producer (866485) <van@i2pmail.org> on Monday April 04, 2005 @12:15PM (#12134547)
    The first problem: They hired amateurs to photograph priceless artifacts. Though the description is short it does include some tip-offs, "skateboard wheels." Sounds like they hired some real flakes that couldn't control the environment they were photographing and they were using inexpensive equipment... I applaud the brothers for their work but it seems like a wasted effort because it could have been avoided if they had hired professionals to photograph the damn thing.
  • Re:Film (Score:2, Insightful)

    by myukew (823565) on Monday April 04, 2005 @12:30PM (#12134684) Homepage
    maybe they had no 8000dpi scanners back in a time when normal people could build one of the fastest supercomputers in the world and pay less than $80k

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