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Science

Massive Mosaic of Canada 46

Posted by michael from the too-much-canuck dept.
rvr writes "Thanks to compression technology that has reduced the file to 3.3 gigabytes and a collaboration between the Canadian Forest Service and the Canadian Space Agency called the 'Earth Observation for Sustainable Development of Forests', this gigantic image -- the highest-resolution image of Canada freely available -- can now be downloaded to your computer."
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Massive Mosaic of Canada More

Massive Mosaic of Canada

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  • It had to be said. Even (especially!) if they can pacel out their bandwidth by making you contact contact "Jeff Dechka, Remote Sensing Data and Product Coordinator at the Canadian Forest Service's Pacific Forestry Centre in Victoria at jdechka@pfc.cfs.nrcan.gc.ca" to download it.

  • kinda skimpy on the technical details (Score:3, Interesting)

    by blackcoot ( 124938 ) on Thursday December 18, 2003 @09:01AM (#7753441)
    since i just did a large project project on image compression techniques, i'm really curious to know what they did to get the 28:1 odd compression ratios. based on my (admittedly limited) playing around with jpeg 2000, this seems like it would be an ideal application (in fact, i'm fairly certain they could squeeze even more data into that space at equivalent quality). in my experiments, jpeg 2000 beat the snot out of everything else (using the lovely jasper toolkit)... i don't know of too many other formats which can achieve 100:1 compression ratios in natural images and still have the results be recognizable. either way, very cool for an image processing geek like myself.

    • Re:kinda skimpy on the technical details (Score:4, Informative)

      by kilonad ( 157396 ) * on Thursday December 18, 2003 @09:37AM (#7753746)
      Having worked on GIS imagery before (from the Australian government), I'm assuming it's in MrSid format. The 100:1 kind of compression ratios are completely legit, it's really incredible. I believe it uses fractal compression of some sort. It's produced by LizardTech [lizardtech.com].

      JPEG and JPEG2000 are great for compressing images where you care more about how it looks than preserving the actual data since they use psychovisual enhancements. MrSid does a much better job at preserving the integrity of the data at much much higher compression rates.
      • I have found MrSID compression to be extremely lossy beyond about 20:1. (That's still alot!) I agree - jpegs suck for mapping. My 0.02.

      • Re:kinda skimpy on the technical details (Score:4, Informative)

        by forged ( 206127 ) on Thursday December 18, 2003 @10:40AM (#7754361) Homepage Journal
        LizardTech make some other awesome products such as Genuine Fractals [lizardtech.com] for Photoshop. Incidentally this is also used by DSLR photography enthusiasts to sharpen [att.net] their images better than most traditional techniques are able to achieve.
      • how do you measure the degree to which the integrity of the data is preserved? psnr? mse? some other metric? i'm curious because jpeg2k is radically different from jpeg. and what in geospatial imaging qualifies as important data? reason i ask is that at least as far as computer vision goes, we lack the knowledge necessary to extract important image features other than texture, edgels, and "corners". in fact, there's often so much redundant information in an image that you pretty much have to throw away 80-9
      • MrSid is kinda a proprietary format though, which is unfortunate. When I needed to extract a MrSid file under Linux to a JPG format, I had to run the free (beer) DOS binary version of the MrSid converter that they provide, inside of Wine.

        I seem to recall them offering some sort of binary-only Linux version, that didn't work or something. I know I couldn't get a JPG of the whole image out of it.
    • since i just did a large project project on image compression techniques, i'm really curious to know what they did to get the 28:1 odd compression ratios

      That's easy; they just compressed the parts of Canada that have nothing in it.
    • The image took me 19 hr to download.

      The download instruction page [nrcan.gc.ca] states "The full mosaic image file is in an ECW format. You can view this product with a free viewer called ER Viewer...

      ECW is Enhanced Compressed Wavelet. [ermapper.com] developed by ERMapper. The image was compressed using ECW because it was pieced together using ERMapper. 3.2 GB fits nicely on a DVD.

      Has anyone else downloaded the image? How long did it take?

  • Heh. (Score:5, Funny)

    by Scarblac ( 122480 ) <slashdot@gerlich.nl> on Thursday December 18, 2003 @09:19AM (#7753584) Homepage

    this gigantic image -- the highest-resolution image of Canada freely available --

    Everyone who thought that was a direct link to the actual image raise your hands :-)

    Know the feeling? "Man, that's going to be the biggest Slashdotting ever! Poor Canadians! Must... click... link..."

  • Apparently Canada Has Expanded (Score:5, Funny)

    by Cy Guy ( 56083 ) * on Thursday December 18, 2003 @09:25AM (#7753629) Homepage Journal
    The picture (or at least the thumbnail versions) contains all of New England, New York, Michigan and much of the Midwest, Pennsylvania, and New Jersey. And I think a parts of the rest of the northern border states.

    But I for one welcome our new Canadian Overlords.

    • The picture (or at least the thumbnail versions) contains all of New England, New York, Michigan and much of the Midwest, Pennsylvania, and New Jersey. And I think a parts of the rest of the northern border states.

      Shhh! It's part of Operation Snowgoose. Why do you think those States considering importing cheap prescriptions from Canada are included in the photo? ;-)

      But I for one welcome our new Canadian Overlords

      Free medicare for you!


  • Nothing against Canada - some of my best friends are Canadian (that doesn't mean I'd let my daughter marry one) BUT:

    Are high resolution satellite/aerial images available for other locations?

    No, I don't expect to be able to buy hi-res images of Area 51, but was looking for my neighborhood.

    Also, are there ways of getting really nice poster prints of high resolution images?

  • No Wonder Their Taxes Are So High (Score:3, Funny)

    by fuzzybunny ( 112938 ) on Thursday December 18, 2003 @09:40AM (#7753776) Homepage Journal
    Bob: Do the theme, eh?

    Doug [gives Great White North theme]

    Bob: Good day, eh. Oh, hey, do our new movie theme, eh?

    Doug [gives Great White North fanfare]

    Bob: Beauty, eh? Good day, I'm Bob McKenzie, this is my brother Doug.

    Doug: How's it going, eh?

    Bob: Wait a second, you hoser, you can't spend all that cash on this big mosaic thing, eh? That's dad's beer money!
  • It is more significant to know the image resolution than the file size. This is represented by the number of ground units a single pixel takes up. 5 meter resolution refers to each pixel being 5 square meters (obviously). For mapping grade imagery, you want at least 5 meters. The standard is moving much closer to 1 meter as companies like Space Imaging [spaceimaging.com] start to dominate the market.

    The performance is TERRIBLE on single large images, if you plan to use it at multiple zoom scales. It is much more efficie
  • no really, I can [nrcan.gc.ca]
  • Clearely this must beat the giga pixel [tawbaware.com] stitch which I remember from not long ago. OK arguably not the same thing, but I had that in mind when I read about the size of the images.... The result is a massive mosaic of digital images 85 gigabytes big. I mean, Geez :)
  • Ahh man my porch light was on.

    Really who read the headline and thought they would actually put up the 3.3gb file. Now that would be a slashdotting to remember
  • These pictures are clearly from the 70s; the cities are purple and the rest of it is neon green. Obviously the work of blacklights.

  • But it's Canada... (Score:1, Funny)

    by Anonymous Coward
    Damn you canada, damn you!!!!
  • Link to the download page: http://www.pfc.cfs.nrcan.gc.ca/eosd/resources/mosa ic_e.html [nrcan.gc.ca]

    Anyone have a torrent yet?

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