Open Source GIS – gdal2tiles

I’ve been starting to try to wrap my head around Open Source GIS tools lately, thinking about how we can use them for our projects.  In this process, I’ve done a decent amount of research, lots of downloading and installing, troubleshooting installs, and figuring out how all of these puzzle pieces fit together.  I come from a liberal arts education background and have always loved GIS because of its combination of science and art (heavy on the art).  So, naturally, the past couple of weeks have been a whirlwind of understanding, black boxes of mystery have slowly opened up and revealed themselves.  Within one of these boxes was the gdal2tiles tool from the OSGeo4W install.  It quickly and easily takes large georeferenced images (jpg, png, tif, etc) and chops them up into manageable tile sizes at standard on-line mapping zoom levels.  So instead of drawing and re-drawing a 50mb image of the Bay Area every time you pan to a new location , this allows you to draw small, seamless tiles, pieces of the whole image as you pan around.  My test here is a 10-meter hillshade of the SF Bay Area at seven different zoom levels.  Lots to build off of, lots of ideas going now, steamrolling ahead into the OS Geo world.

bayareahs1

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7 Responses to “Open Source GIS – gdal2tiles”

  1. Dane Says:

    Nice Tim,

    You might also be interested in this application of the gdal utilities, dems, and mapnik: http://mike.teczno.com/notes/hillshading.html

    And in the recent Mapnik 0.6.0 release we’ve added native transparency and composing support (http://trac.mapnik.org/wiki/RasterSymbolizer)

    This will allow you to render hill-shaded tiles while overlaying vector data.

    • tsinn Says:

      Dane, thanks for the links! I’ve been reading Mike’s blog for a bit now, but hadn’t seen that particular post. Really pushing things forward, and it’s a great place to get ideas. Also downloaded and have been learning the ins and outs of Mapnik. Powerful stuff, and seems incredibly useful for all that GreenInfo is doing these days. A shift toward on-line custom cartography and maps instead of just data overlays on GMaps, VE, etc.

  2. matt Says:

    GDAL2Tiles Rocks! Just FYI, there is also a GUI interface, called MapTiler (http://www.maptiler.org/). The command-line version of course still wins out for those times when batch processing is necessary 😉

    • tsinn Says:

      Matt, I gave MapTiler a try, seems like a straightforward GUI, but the resulting tiles were just gray. I didn’t spend too much time trying to troubleshoot before shifting over to command-line gdal2tiles, which gave me flawless results. Thanks for the tip!

  3. Stephen Fuhry Says:

    Great post tsinn! I’ve got a floorplan of a warehouse setup with GDAL2Tiles that i want to put a whole bunch of vectors on it so people can click on them and see what items are there and whatnot.. I’m kind of at a loss though as to what tools i need for this.. Any suggestions?

  4. Ana Says:

    I have GDAL 1.6 but there´s no gdal2tiles.py on it. How can I get it/upgrade it? Someone help me please

  5. Tejas Gajera Says:

    Is there any way to speed up the GDAL2Tiles? I have tried to use it on very large Tiff image (30-40GB), and look like it takes forever to complete this (more than a week and still running).

    Any kind of idea will be appreciated.

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