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I am about to make a map with a heavy emphasis on cartography. I would really like to spice it up by processing the image in GIMP and I was wondering if anyone had any tips for bringing the cartographic pain to some ArcMap exports.

My current plan is to export certain layers and elements individually and process them, but I will be clicking in the blind so I am looking for suggestions.

What are some techniques for processing these exports with GIMP to produce a map?

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    What is the thematic purpose of the map?
    – Mapperz
    Mar 31, 2014 at 18:20
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    Cartotalk is an excellent site, and if you want, you can ask for a review.
    – mkennedy
    Mar 31, 2014 at 18:35
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    I made some edits to your question to try to focus it a bit more, but I am leaning towards voting to close this as "too broad". Your question is a bit too much "how to use GIMP?" and not enough "how can I achieve this specific cartographic effect?", for example.
    – blah238
    Mar 31, 2014 at 22:44
  • Thanks for the comment, I was struggling to find an appropriate way to communicate what I am looking for. I think you nailed it. Apr 1, 2014 at 14:52
  • think about if GIMP is the best solution for postprocessing since it is more an Image Manipulation Software. For vector data Inkscape might be the better choice if you need free Software.
    – Chris P
    Apr 2, 2014 at 7:19

3 Answers 3

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I wouldn't do this, especially not if I have ArcMap available or QGIS and want to keep my sanity whilst also having an understandable map!

ArcMap and QGIS have some excellent cartographic tools which, in combination with appropriate symbology working directly on the data and what it means geographically (as opposed to merely post-processing an image) allow you to present the data in ways that are both attractive and informative. To achieve this with GIMP alone will be a nightmare.

The trick is to learn to use ArcMap and QGIS to their full.

Some of the problems with doing cartography in GIMP are:

  • Matching the legend to whatever artsy stuff you do in GIMP and still have the two relate to each other
  • GIMP, Photoshop and most other image processors do not understand many GIS formats -- vectors being the obvious choice -- and multiband rasters (more than four) with a greater pixel depth than 8 bits in many cases are meaningless to to them
  • Losing all georeferencing information so you will have to align your layers by eye (even with grid snapping, it's not ideal)

... the list of downsides goes on ...

If you must step outside of ArcMap and QGIS, then I would strongly recommend learning to use map renderers such as Mapnik, but to be honest, life will be a lot easier doing it via a dialog UI as presented in both QGIS and ArcMap (other GIS packages with excellent cartography elements are available).

Something I have done is to use GIMP and Inkscape to create fill patterns and use those from within ArcMap/QGIS (i.e. the opposite of what you intend).

If you want different North Arrows or other map furniture than is available as standard, then again, I would do this separately and import it into Arcmap/QGIS.

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  • Thanks for the comment. I was curious if there was a tried and true method for making things look a little better. I have gotten to the point of placing halos on everything (at least it feels that way). Apr 1, 2014 at 14:54
  • Adding halos is a very basic improvement in some cases but have you explored the full functionality ArcMap offers to control halos, backdrops, shadows, text, font, kerning and multi-layer symbols? There is also the Cartography Toolbox, which provides tools for creating/editing data for presentational purposes. You have FAR more control doing this from within ArcMap than exporting a half-finished product to GIMP and trying to improve it there. Apr 1, 2014 at 15:01
  • "life will be a lot easier doing it via a dialog UI as presented in both QGIS and ArcMap" Could not agree more! Apr 2, 2014 at 14:19
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What is it you need to accomplish that you cannot do in ArcMap? There isn't much that cannot be done directly in the ArcMap layout other then special effects on selected graphics (Transparencies, drop shadow, etc.)

I would recommend doing all your cartography in ArcMap because, it is much easier, and if you miss some errors during production, it's easy to correct these.

Once you export Your map to an image or vector file from ArcMap the whole process becomes graphic design and image editing. Hence, it helps to have an in-depth knowledge of both vector graphic and image manipulation in whatever software you prefer. Personally, I prefer Adobe products but Corel also has capable products. I am not familiar with GIMP and might be great to tweak the raster layers of a map but you should handle vector layers separately.

ArcMap allows you to export directly to an AI (Adobe Illustrator) vector format, (rasters are rendered as images in the same file). Illustrator is probably the best way to fine-tune your final product but I personally I don't like how ArcMap renders rasters to AI. (THis would be a long discussion) I prefer to export a single map into separate files - rasters as a high res tiff or jpeg, vector layers as a seperate AI file and the layout frame, graphics + legend as another AI file. I then combine or link these in Illustrator but recently I have been only cleaning up the separate files in Illustrator and then creating the final product in Adobe InDesign. Most folks think of InDesign as a magazine/book publishing but it is actually better suited for designing large graphics (posters, maps) then Illustrator.(Again, this would be a longer discussion and one which is more related to graphic design then GIS)

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You can export the file as an EPS (In ArcMap go to File > Export Map and in the drop down just select EPS) and load it into GIMP.

As long as you have GhostScript this should preserve each layer -- unlike saving as a JPEG, or PNG which just combines everything into an image -- so you don't have to export each layer/ feature individually.

As for actual design tips, some of the simplest things make a huge difference -- something as small as changing the north arrow and scale bar from the default black to dark grey so that they blend into the map makes a big difference.

Each person has different tastes so it's hard to give any other design tips without actually seeing what you want to map but I find keeping things neat and tidy, trying to emphasize the important aspects of the maps while muting the less essential stuff works best.

Also for choosing colours, I would recommend ColorBrewer as it also lets you find colour schemes that are suitable for the colour blind.

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