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Garmin Custom Maps

I have created a Custom map using Google Earth and successfully loaded it into my eTrex 30. However, after turning on the eTrex there was an error message - the file is too big. I can compress the map file, but what is the maximum size I can use?


  • gerano 31 Points
    Hi sussamb,

    Thanks for very quick response. It was very useful indeed. Map is now visible on eTrex.
    When map is small it has dotted diagonal lines obscuring detail below. When enlarged dotted lines disappear, but it looks as though map has been transferred with reduced opacity and thus is not clear in use. Later I will change opacity in Google Earth to 100% and try again.
    Most impressed how quickly one can get help. Have a great day.
  • Boyd 1974 Points
    edited June 2014
    Transparency is not supported in custom maps, so I'm not sure what you are looking at but it is not related to the transparency of the image in Google Earth. The technique in sussamb's post is fine for starters, but only suitable for very small maps. To make maps that are actually useful for anything more than a short walk, you will need a third party tool.

    There are a couple good ones that you might want to look at here. They will allow you to make much larger maps that utilize the maximum of 100 images embedded in the .kmz file.
  • gerano 31 Points
    Hi Boyd,

    I have had a look at your two suggestions for which thanks. Whilst I am familiar with the file types associated with photography, the ones referred to in G-Raster are new to me. It appears a map scanned as a tiff file and then opened in Photoshop cannot then be saved into the required format for the G-Raster program. Can you help again here?
  • Boyd 1974 Points
    It depends on what you're doing. When at all possible, it is best to download digital versions of raster imagery when making custom maps. This kind of file will already have associated data that correctly positions it on the face of the earth. There are many sources for this kind of imagery, one of them is the National Map:

    Most states and many cities/counties also have sites where you can download free geodata.

    If you scan your own paper map, then you will have to do the georeferencing yourself. Personally I use some powerful GIS software and not the programs in the links above. But I beleive they include tools for you to georeference your own scanned images. So I don't think there is any problem creating your own map in Photoshop as a TIFF, JPEG or other raster format.

    If you download geoTIFF files and want to edit them in Photoshop, that is certainly possible - I do it all the time. But Photoshop (at least my old version) discards the georeferencing data which breaks the map. The key in making this work is to use two companion files that specify the coordinates and projection, so if your file was named myMap.TIF, you would also have a world file named myMap.TFW and a projection file named myMap.PRJ. These should be part of the origial downloaded data.
  • gerano 31 Points
    Thanks for your continued interest.
    I live in South Africa where geo-referenced maps available to download seem rare. My intention is to use scanned maps of hiking areas, saved as tiff files, where the latitude and longitude are stated on the map. They may be edited in Photoshop CS6. How do I convert them into a format acceptable to G-Raster to import? In Google Earth I was able to input co-ordinates, import and adjust map positioning.
  • Boyd 1974 Points
    As I said, I don't personally use these regularly, i use more powerful/expensive software. But I have played with mapc2mapc a bit and it looks very cool. One nice feature is that you can make irregularly-shaped maps (instead of rectangular). I think it will do what you want, it should read PNG, JPG, TIF, GIF, and BMP images from Photoshop. You can then georeference them - see:

    I think the best approach is just to give it a try, the free version is fully functional but it puts red X marks on the finished map.
  • gerano 31 Points
    I had a brief look at the software. It looks very straightforward and user friendly. I will try to find time soon to try it out.
    Very helpful advice - thanks.
  • gerano 31 Points
    Hi Boyd,

    I am up and running with the software you suggested. It was good advice.
  • Boyd 1974 Points
    Great, glad to hear that it's working for you. :)
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