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The use of background maps by GPS users in Latin America always has presented difficulties because of the lack of available digital maps. For developing countries, the main source of cartographic data are the government agencies that often don't possess structure and budget to provide the maps that the market demands. GPS manufacturers have had to resort to public domain maps supplied by the government of the United States, through US Defense Mapping Agency. These maps possess a low level of detail but cover all the World.
The pictures below show the city of Belo Horizonte respectively in the Garmin MapSource®, Lowrance MapCreate® and Magellan MapSend®. Note that in all, there are no significant details that help with GPS navigation.
Since 1998 I have receive hundreds of e-mails complaining about the level of map detail provided by Garmin™, Magellan™, and others.To their credit, this limitation is not exclusively the manufacturers's fault - obtaining digital maps of developing countries is an almost impossible task.
You can't imagine the difficulty that I have had obtaining a digital map of my city. I tried to acquire municipal maps from the City Hall in AutoCad-DXF format, but they said the maps would cost US$10,000.00. I also contacted some companies that specialize in cartography, who offered me street maps for US$1,200.00, with restriction for any redistribution. If the cost of the maps for a single city is so expensive, imagine the cost of detailed maps of a whole country with more than 5500 cities, like Brazil!
The Policy of the GPS Manufacturers
Up to now it is possible to obtain maps with a good detail level for countries in North America, Europe and a dozen of other countries. The GPS manufacturers pay a premium for the digital maps, passing the cost on to the consumer. To impede the unauthorized copy of the maps, each company creates its own encrypted system or a system of binary files with indefinite structure to protect their data.
Unfortunately, this policy restricts other people from creating their own GPS maps in each manufacturer's proprietary format. If the format of the maps is binary with difficult interpretation or encrypted, it is almost impossible for a normal user to create their own maps.
Certainly there is demand for GPS hardware and software that allows users to create background maps with whatever level of detail is desired. Imagine the following situations:
- A big national park located in Canada wishes to purchase 100 GPS devices to rent to the visitors, with maps of the trails and tourist points already defined inside the GPS.
- A big delivery company wishes to purchase 500 GPS devices to create their own maps inside of the GPS, to aid the delivery vehicles.
These are real applications that have not been developed because of the difficulties involved in creating customized maps for GPS.
Creating your own Maps for Garmin™ GPS
Because Garmin™ has seemingly ignored the demand for software tools that allow consumers to create their own maps, some talented European developers have written programs that can produce un-encrypted MapSource® IMG files - IMG files are the actual map files that are downloaded to Garmin GPS units. Two examples of these programs are MapDekode created by the Austrian Peter and GPSMap. The present article treats of the use of the Mapdekode program, but you will find a lot of information on GPSMap website and in an article written by Adam Newham.
These use of these programs does not violate Garmin's copyrights since users create maps starting with their own data (waypoints, routes and tracklogs) and the resulting IMG files are read by Garmin's own MapSource program.
The creation of maps for the Garmin™ GPS follows the model below:
Notice: The Author does not provide
technical support for questions relating to the creation of
To create your own background map for Garmin™ GPS, you will need:
The following software versions were used in writing this article:
Before you begin, take a look at the document below:
Document of Compatibility
General View of the Structure of a Map
Example: Map of Brazilian Highways between Belo Horizonte - Uberaba - Ribeirao Preto
We will create an example of a map that shows each curve of the main
highways in full detail between the Brazilian cities of Belo Horizonte,
Uberaba and Ribeirao Preto.
The Trackologs and Waypoints of the first file were obtained with a GPS III+. The second file was created starting from the maps of the Yellow Pages of Belo Horizonte.
Before getting started, create two directories on your computer to store the maps. The first will store the General Map, and the second will store the Detail Maps:
Step 1 - Creating the General Map
- Click here to download the file highways.gz and save it to the C:\Maps\ directory.
- Open highways.gz in the GPS TrackMaker® program
- Eliminate all Waypoints, only leaving the Waypoints of Belo Horizonte, Uberaba and Ribeirao Preto.
- Modify the Waypoints of these cities for "City Large"
- Create a Tracklog around the whole map, rename it to "Example" and apply the "Yellow Map Background" style. Press the "Send to Back" button to send the Tracklog behind the other Tracklogs. The "Yellow Map Background" style will inform Mapdekode the limits of the map.
-Create the borders of the Detail Maps that will be used later. For that, make eight Tracklogs in form of rectangles and apply the "Green Map Border" style, which informs Mapdekode the limits of the Detail Maps. Rename the eight Tracklogs to the names of the future IMGs that will be created. Each IMG must have names with 8 numbers inserted in the <F=xxxxxxxx> tag . In the example, the names were:
- After the modifications, the file will have the following format:
- The modified file is available to download in highways1.gz
Step 2 - Compiling the General Map in the MapDekode Program
The next step is to create the IMG file of the General Map using the MapDekode program:
- In the GPS TrackMaker® program, export the "highways1.gz" to the DBX
format of MapDekode.
- The DBX file created starting from "highways1.gz" is available for download in highways1.zip
- Open MapDekode and click in "Map Create" -> "Overview-map from DB (*.DBX -> *.img)"
- Choose Zf = 15 (5.6th; 19m) and press OK. With this parameter, the smallest detail of the General Map will have 19m turning a simplified map, exactly as we want for the General Map.
- Open the file named "highways1.dbx"
- After the compilation, a file named "highway1.img" will be created in the same directory
* * You have just created the IMG of the General Map! * *
Step 3 - Creating the Detail Maps
Eight borders of Detail Maps were created on the General Map with the
"Green Map Border" Tracklog style. Now we need to create each one of the
eight Detail Maps that can be loaded in the GPS through the MapSource®
- Open the "highways1.gz" file (General Map) in the GPS TrackMaker® program
- Double click on the Tracklog of the "40000001.img" map and press CTRL C to copy it.
- Create a new file and paste the border of the "40000001.img" map pressing CTRL V
- Change the Tracklog style to "Yellow Map Background" and change its name to "Map 1"
- After eliminating the excesses, use again the "Merge File" tool to add the main avenues of Belo Horizonte city contained in bh_avenues.gz
- Use the "Tracklog Reducer" tool with the "Cut Tracklog if exceeds... " option to reduce the Tracklogs to less than 255 points. A reasonable value for the Tracklog size is 230 points.
Brief comments on the Level of Zoom
The definition of the scale is important in the Detail Map, because it eliminates the excess and the confusion of data in larger scales. The definition of the scale can be made directly in the window of Edition of Tracklogs and in the window of Edition of Waypoint Styles.
Instead of using the predefined scales of the GPS TrackMaker®, you can also use the notation "<Z = 0 to 5> " after the name of the Tracklog or after the comments of the Waypoint. The result will be the same.
For the present example, zoom levels were introduced among 0 to 3 for
streets and avenues of Belo Horizonte. For the rest, the level of Zoom was
maintained to "0" or "Permanent".
Tip: Level of Zoom for Waypoints in the free version
Users of the free version of GPS TrackMaker® can use the tag
<Z=x> to define the zoom level but possibly will have difficulties
configuring the 6 levels of Zoom for the Styles of Waypoints, because only
the Professional version allows the creation of new styles of
Step 4 - Creating the Eight Files of the Detail Maps
The procedure described in the Step 3 must be repeated for each Detail Map. Each map should be recorded with 8 numbers in the name and with the same suitable name in "Green Map Boder" of the General Map.
Step 5 - Compiling the Eight Detail Maps to the MapSource® Format
The next step is to create the IMG files of the Detail Maps that can be sent to the GPS as background maps.
- Using GPs TrackMaker®, export the "40000001.gz" file to the DBX
format of Mapdekode.
- Save the "40000001.dbx" file in C:\Maps\Details
- Open Mapdekode and click in "Map Create" -> "Detail-map from DB (*.DBX -> *.img)"
- Choose Zf = 17 (1.4º ; 4.8m) and press OK. With these parameters, the smallest detail of each Detail Map will be 4.8 m, giving a reasonable resolution on the GPS screen.
- After the compilation, a file called "40000001.img" will be created .
- Repeat the procedure for the other files.
-The eight Detail Maps in MapDekode format are shown below:
Step 6 - Registering the new IMG files in MapSource®
Up to now, you created one file for the General Map and eight files of the Detail Maps that were recorded in two directories as shown below:
The last step is to inform MapSource® that a new map was created and the directories where are the files of the map. That is done with the Mapdekode program:
- Open Mapdekode and click in "Project"
- Register the project clicking on: "TDB" -> "Save TDB and make Reg-entry"
- After registering, it is time to add the Detail Map to the
Ready! A new map for MapSource® was just