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Thread: Gigapixel raster map conversion - Software suggestions?

  1. #1
      craigspc is offline
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    Question Gigapixel raster map conversion - Software suggestions?

    Hello,

    I'm new to the forum, so I hope you don't mind me jumping straight in with a question.

    I have a VERY large raster map (60,000 x 60,000 pixels) which I would like to develop further. Unfortunately, when I started this project a few years ago, I did so in Adobe Photoshop. I have since established that the map would be easier to work with in vector format. However, I'm struggling to find an application that is good for cartography, yet capable of working with extremely large and complicated images.

    To give you some idea of what my map looks like, here's an example. Please note that my original works doesn't contain any drop shadow or other special effects. It is simply a two colour (blue and white) image:




    As you may be able to work out from the sample, my map is of a network of waterways. The example only shown is a tiny portion of one lake. However, my map covers a much larger area of wetland, which includes numerous lakes and rivers. I really would like to retain the detail from my work, but this is my problem.

    Due to the simple two-colour nature of my map, I was able to use the 'Select Colour Range' in Photoshop, then convert that selection into vector paths. I also managed to import these paths into Illustrator. So far so good, but there is a problem...

    In order to retain an acceptable level of detail in my map, the simple outline of the water mass requires somewhere in the region of 500,000 anchor points/nodes. Illustrator was able to accept this, but it is becoming clear (well, it would appear) that the program is not going to be capable of letting me develop the map much further. The application is already showing signs or reaching its limits on the performance front and I haven't even started to add any additional features/layers to it.

    By home standards, my PC is fairly powerful. I use a Windows based PC with a Core i7 965 processor with 12Gb or RAM. However, Illustrator is not able to make use of the additional memory, nor is it capable of exploiting a multi-core processor.

    Can anyone explain what kind of application would be suitable for my needs? Having spent several years producing the detailed maps, I'm very reluctant to reduce its detail considerably in order to accommodate Adobe Illustrator.

    Many thanks in advance,
    Craig.

  2. #2
      Redrobes is offline
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    Hi there, I deal with very large maps too, often 20K, sometimes 40K but with biggest at 120K pixels square. In all these cases I work in tiles so that you don't have the whole map in ram at one time. When I need to tile a map that's usually pretty easy up to a certain limit then it gets hard fast. When it gets past about 32K square I need the raster as raw RGB format and then deal with it on a byte by byte basis. But it helps not to have it un-tiled to start with.

    Once in tiles then I think it would be more sane to convert to vector format and stitch up the edges. 60K would mean something like 4x4 16K tiles tho so its pretty big even then.

    On the tech side you need a 64 bit OS and the apps need to be 64 bit too before it will use >3Gb but I assume you know this already. Don't know much about Adobe apps in this regard or what you might use to convert. Maybe there is an inkscape in 64bit since its open source. I know that can vectorize bitmaps. Theres an open source Xara which can do that too but not for windows I hear anyway, I would try to find a command line version and script it. I can tell you image magick is no good at all for this kind of thing tho. Its memory heavy and slow though I still like it for other things.

  3. #3
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    60k x 60x pixels? Wow - it's just hard for me to get around working in that large a scale.

    And Red - you may have inadvertently given me a solution to a particular mapping problem I've been facing in suggesting working in tiles. Thanks!

  4. #4
      craigspc is offline
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    Thanks for your feedback. I'm currently using the 64 bit version of photoshop, which handles the raster image really quite well. Unfortunately though, Illustrator is a different story. I'll have a look at the open source options such as Inkscape and see what is available. Thanks for the tip on tiling too. I'll give it a go and see how I get on.

    Best regards,
    Craig.

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