Slashdot Mirror
Gigapixel Tapestries & Gigadecimal Pi
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."
I know this is intended at a joke, but I saw a research project at Southampton University about 5 years ago that allowed multi-gigabyte images to be viewed over the Internet. Each image was split into small tiles, and lower resolution tiles were made of each segment. The entire image could be viewed at low resolution, and the user could then zoom in to the full resolution on any given area. The intended use for this system was high resolution scanned images of paintings in art galleries.
I am TheRaven on Soylent News
rather than stich a bunch of digital photos, they should have simply photographed it with a very large format camera, and had the resulting negative drum scanned at 8000dpi. These folks do it that way, and if you take a look, the resolution is amazing.
Douglas P. Price
The colours in tapestries are usually vegetable dyes and they fade very badly with exposure to light. If you go around a museum, the tapestries almost always look dingy and you need to use a lot of imagination to try to picture how they might have originally looked.
However the back of the tapestry has been kept in the dark and the colours there are still dazzling. So ... if you have a good picture of the front and the back and you can resample the back image to get it to line up with the front to within a knot size, you can use the back colour to "re-tint" the front image and get an excellent visualisation of how the tapestry might have appeared soon after it was woven (you need to take a bit of care with colour management too).
A friend of mine did this as part of his PhD thesis. I can't find any of his images online (I guess there would be copyright problems), I'll see if I can dig some low-res ones up.
Ah! Found it.
How do we *know* that pi is exactly the result of the formulas that these people use to calculate pi?
I only ask because I assume that pi (as defined by the number of times the diameter of a circle can be wrapped around its circumference) might differ at some arbitary point into the calculation?
How do we know that these calulations actually produce a number that matches reality?
Pete