Sunday, March 18, 2012

Making custom (not counterfeit) maps for your GPS

There was a story last week about counterfeit GPS maps causing drivers to get lost in Shanghai, which was widely reported in mapping blogs (like GeoCarta and The Map Room) and discussion groups.  But what do they mean by counterfeit maps? Jesse at Very Spatial started to address this, saying "I disagree with their use of the word ‘fake’, inaccurate is more realistic."  You can make custom maps for your GPS that may be sloppy or deceptive, or they may be more accurate than what you can buy commercially.

Let’s take a look at how this is done. What follows is a brief overview of a subject covered in great detail in my book, GPS Mapping – Make Your Own Maps, which includes step-by-step instructions.

Why would you want to do this? Well, you might be traveling to a foreign country for which there are no good GPS maps. Or you might just want better topo maps than what is available commercially. This is a common problem for outdoor recreation enthusiasts, as almost all GPS maps are based on 1:100K scale data, the one exception being Garmin’s US Topo 24K series (Amazon), which only covers national parks. Garmin’s US wide product (Amazon) shows contour lines 130 feet apart. I don’t know about you, but I like to know if I’m about to ride my mountain bike off a 100′ cliff! And while the Magellan (Amazon) and Lowrance products show contour lines much closer together, they actually interpolate the 1:100K data to do so, which is misleading to say the least.

On to how to make custom GPS maps…

The first thing you have to do is obtain your data and convert it to the proper format. We’re talking vector data here, not scanned (raster) maps. Map data can consist of GIS file types such as shapefiles, or info like digital line graphics (DLG’s) from USGS or other sources. From there, you just need to get it into your GPS. There are different techniques for different brands…


Perhaps the most popular method for Garmin relies on  cGPSmapper. An excellent resource for these  techniques re: Garmin units is the Yahoo Map Authors discussion board. And despite what you may read, this can be done without registry hacks or tracing contour lines. It’s all covered in my book, as is the process for Magellan and Lowrance. 


As much as I love Garmin, I have to say that the process of loading the maps into a Magellan is much easier, thanks to their free MobileMapper Office software.  The best web reference on the process is the Yahoo MobileMapper2 group.


Unfortunately, it’s been a while since you could hack a Lowrance map. Folks with MapCreate version 4 could do it, but we’re now up to version 6.3. There is a solution available to Lowrance users though, as their mapping units tend to have extensive track memory, allowing you to layer roads, contours, etc., as tracks. UPDATE: You now have more options for creating custom maps for Lowrance GPS receivers.

A caveat on routing

Making maps is one thing. Making them "routable," allowing for turn-by-turn directions on roads, is another thing entirely. Maybe that’s where the Shanghai hackers ran into trouble.

About Rich Owings

Rich is the owner, editor and chief bottle-washer for GPS Tracklog. Connect with him on Twitter, Facebook or Google Plus.


  1. Fernando Piza says:

    I Live in Colombia South America and I bought a Lowrance I Finder expedition c because after a deeo study i sow is the best. But I have a problem there are not maps of Colombia for this unit. How you can help me?

  2. I bought a LOWRANCE I FINDER EXPEDITION C , because I think is the best , but I have a problem. I live in COLOMBIA SOUTH AMERICA and I can´t find maps of COLOMBIA for this GPS .
    You can help me any way?

  3. Fernando,
    Lowrance has a worldwide map product , but the detail will not be very good. I think you’re limited to making your own maps for it. Fortunately, some progress has been made in that regard when it comes to Lowrance. See

  4. Fernando PIza says:

    Thanks Rich for your advise; unfortunatly the two links you give me dont work . Tell me if with your book only I can make maps for my Lowrance I Finder expedition c.
    Fernando Piza

  5. Fernando, try the links now. They should work. My book covers how to prepare data to transfer to your Lowrance, but it does not go through the steps required to actually do the transfer.

  6. Is there any way of converting Garmin BlueChart data to shapefiles or to transfer them onto the handhelds?

  7. I don’t know of any way to convert them to shapefiles but you should be able to load them onto a compatible Garmin handheld.

  8. May I please ask…..can I download the Australian map into my GPS. Its not there because I bought my GPS in China, and now all it has is the China map. I was wondering if I can download the Australia map on it. Please help me solve my problem!

  9. Annie, what kind of GPS do you have?

  10. I travel a lot to foreign countries where there are NO detailed maps… even published hardcopy. I would like to find a GSP unit that will allow me to capture a trip, upload it to my computer and make a map. The map needs to be relatively accurate, with waypoints and editable so additional directional info can be added.
    I am new to the GPS world, so this might be something obvious. But, could someone advise on the best unit and the best software that would support this… if it is even possible.

  11. I have img and imi files of maps. Multiple maps. I understand you can only have one map on card at a time. I downloaded those to my sd card, but my gps does not recogiznied it. these are for marine section of gps. How can I make my gps read these files or do I not have everything I need to initialize these maps

  12. Use SendMap to transfer the .img file. Download SendMap for free from here… (scroll down)
    You should be able to connect your GPS and just drag the .img file to the SendMap icon.

  13. Thanks for the response rich, I am sorry I forgot to mention I have magellan crossover gps. I looked at cgpsmapper and I see it is mostly for Garmin. Can I still use the free ware (many different versions on their website), so I can use the .img and .imi files to be read by magellan.

  14. Cindy,
    If the maps were created for a Garmin GPS, they will have to be converted to Magellan format. Details here…

  15. thanks again but the maps are for magellan. I looked at your link but I can not seem to find the right software. Can you point me in the right direction.

  16. Were the .img maps you have originally created specifically for a Magellan unit? If so, you may be able to use the MMO converter, available at
    This group may be able to be of help too…

  17. Hi Rich, I am techie but a newbie in GPS and related Stuff. I have a customer who wants detailed custom maps of Bangalore, India. Any hardware is okay. Please tell me where to start.

  18. Arun,
    I’m no sure it’s really worth it. MapMyIndia is covering India, and Garmin is getting ready to enter it too. If you really want to make your own, I’d suggest making them for Garmin. There’s a lot more info online for making your own Garmin maps than any other type. My book, GPS Mapping, goes over the process, but doesn’t go into auto-routing.

  19. Thanks Rich.
    But I have one more question. Can I customise the existing ones (eg.MapMyIndia’s) to add more POIs? That is exactly what I want. My requirement is to have a map with more POI density than existing ones.
    If possible, is it discribed in your book?

  20. Arun,
    You can definitely add POIs to a Garmin. My custom POI page has some resources:
    MapMyIndia’s navigator appears to let you add POIs, according to the PDF manual:
    Whether or not you can convert an Excel file or the like to POIs, I don’t know. I suggest you contact MapMyIndia to find out. If you learn any more about their custom POI ability, I’d appreciate it of you would let us know.

  21. Thanks Rich, I’ll definitely update u if I get some info worth sharing.
    Thanks again. Arun

  22. Hi all – I have a magellan roadmate 760 – is there a map for australia – I am going there in Decemeber for at least a year 🙂
    I have North America and Europe on the system.

  23. Though dated, see item 12 near the bottom of this page…
    This doesn’t appear to work with RoadMates; they aren’t listed anyway…
    There were RoadMates made for Oz, and a newer Crossover. I’d contact some Magellan dealers there and ask.

  24. Ron Maxwell says:

    I want to be able to go to a remote location and mark it or save it in a GPS device. The locations are remote accessed by mostly unmarked roads. How do I enable a GPS device like a Tom Tom locate my locations and get me to those locations? I have several people who need to find these locations at different times and they are not from this area. What will i do about the unmarked roads? Some of these roads are on private ranch land? Your suggestions and help will be most helpful. Please respond directly to my email
    [email protected] and thanks for reading my problem.

  25. Ron,
    Your manual should tell you how to mark your current position. If you tell me which unit you have, I may be able to help. If the location is off road, you might do better to use a handheld GPS loaded with both topo and highway maps. Are these locations in the U.S.?

  26. Ron Maxwell says:

    It’s a entry level TomTom but I would get the model best suited for this application, one that is easy to use. How would I proceed to make these maps and mark these locations? yes the locations are in the USA in TEXAS. How would I pass this info on to other I know here/ Thanks for your input .
    Sincerely, Ron

  27. Rich Owings says:

    If you just want to create custom points of interest, I think you can do that with a TomTom. See this post for more info…
    I don’t know of anyone making custom maps for TomTom units though.

  28. I have a Brunton Atlas (same as a lowrance). Where can I get a map for Colombia? Thanks

  29. I don’t believe any are commercially available. I think you would have to make your own or switch to a different brand of GPS.

  30. Just purchase a Garmin nuvi 750, and need it for traveling in Mexico. I haven’t seen any decent maps, so I’m thinking about making them. Your book is currently out, is cGPSmapper my best resource, and do you know of any source that goes of auto-routing?

  31. Robert,
    Check this out before you start making your own…

  32. Jim Loveys says:

    Hi Rich;
    Great forum. My situation may or may not fit into the discussion but your opion is appreciated either way. I bought a Humminbird sonar with GPS capability (uses Navionics charts) only to find that there aren’t any hydrographic or topo maps available for Nova Scotia lakes, rendering the option usless. The unit does have what is called a “UNIMAP” which provides some topo features of the US, which is great when I vacation in Maine every summer. Are you aware of a compatible topo map product that can be converted into something usable?

  33. Hi Jim,
    We’re out of my specialty here. A few quick searches make me wonder if there isn’t a relationship and perhaps a degree of compatibility between Hummingbird charts and Lowrance charts. Better places to ask would be
    Sorry I can’t be of more help.

  34. Jim Loveys says:

    Thank you Rich.

  35. Can any one provide me the Bangalore map for my Garmin Nuvi 205W please.
    Or atleast let me know how to make a custom map.

  36. Bill Morton says:

    We have about 500 acres in east central Ohio that is heavly wooded with a number of logging trails that are being cleared for hiking etc. How do we create a map of the trails using a gps device and obtain the maps?

  37. First, make sure you get a handheld GPS with a high-sensitivity chipset so you’ll get accurate readings. Most newer models will have this. Then, walk the trails, and collect tracks (electronic breadcrumb trails). You can save these tracks to display on the GPS as you are hiking in the future, and you can overlay them on mapping software like National Geographic TOPO and use it to generate printed maps.

  38. I have a Magellan Roadmate SE4. Where can I get/ download maps of India compatible with this GPS navigator?

  39. Rich Owings says:

    I don’t know of any sources. The easiest brand to get international maps for (including many that are free) is Garmin. TomTom is next, Magellan is last.

  40. Hi Amit,
    I have also been trying India maps for Magellan SE 4. If you find something please do let me know. I shall also keep you informed.


  41. Hi Rich,

    i am a newbie in this mapping arena. I am curious and yet confuse by all these mapping concepts and terminologies.

    Understand that routing and way-points are usually stored in non-non proprietary file format (like GPX) which can be easily converted into other format using software like gpsbabel so that anyone can create and share their routes in various platforms (be it dedicated GPS units or phone based apps).

    How about maps? Can proprietary maps be easily converted from img to imi etc?

    Thanks so much.

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