• noughtnaut@lemmy.world
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    2 days ago

    I wanted to say “[citation needed]”, this seems to be straight from Wikipedia (which it is, it’s the last paragraph of the “File format” section).

    Unfortunately there’s no clear basis for this information, except a reference to the (entire) “PDF Reference”.

    The article image is essentially identical, but it’s not the same and must have been remade at some point. I wonder if the wiki editor lives at the centre of the square?

    • noughtnaut@lemmy.world
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      2 days ago

      From the reference document:

      “Implementation limits”, p. 991ff:

      PDF itself has one architectural limit: Because ten digits are allocated to byte off-sets, the size of a file is limited to 1010 bytes (approximately 10 gigabytes).

      and

      The minimum allowed page size is 3 by 3 units in default user space; the maximum is 14,400 by 14,400 units. […] Beginning with PDF 1.6, the size of the unit may be set on a page-by-page basis; the default remains at 1/72 inch. (See implementation note 177 in Appendix H.)

      That implementation note, by the way, roughly states that “the UserUnit entry of the page dictionary” is more or less a dimension multiplier, and that:

      Acrobat 7.0 supports a maximum UserUnit value of 75,000, which gives a maximum page dimension of 15,000,000 inches (14,400 * 75,000 * 1 ⁄ 72).

      and

      The magnification factor of a view is constrained to be between approximately 8 percent and 6400 percent. These limits are not fixed; they vary with the size of the page being displayed, as well as with the size of the pages previously viewed within the file.

      All in all, dealing with a page of such humongous dimensions sounds rather bothersome.

      • bier@feddit.nl
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        2 days ago

        This only matters if the pdf has a simple square in it. When it’s an actual scale map, with 1cm detail, it will still be a huge pdf even if it’s vectors.

        • CannonFodder@lemmy.world
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          2 days ago

          Sure. It’s all about the level of detail. An 8-1/2x11" pdf with lots of very small detail that you have to zoom way in to see would also be a very big file.

        • CannonFodder@lemmy.world
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          2 days ago

          True, but that’s independent of the pdf page size. If there’s a 1e12x1e12 complex jpeg image even on a small pdf page, it would still be a huge file.

    • kautau@lemmy.world
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      2 days ago

      Probably small. If it just had a single circle at each corner it’s just 4 objects with really far positioning values.

      You could fill it with more stuff to make it bigger, of course