Raspberry Pi navigation on the open seas

Map Content

The quality of a self-built navigation system depends entirely on the quality of the maps used. Various governmental agencies offer maps for inland waterways, and the situation is even better for coastlines along the Atlantic Ocean and the Baltic Sea, where I would be sailing. In addition to OpenSeaMap maps [7], the Federal Maritime and Hydrographic Ministry of Germany (BSH) also offers material in the form of vector maps that can be downloaded from the BSH server.

However, avNav expects maps with a specific format, namely the Osmdroid GEMF format. In a show of generous good will, Vogel has posted a description of preparing maps for avNav on his website [8]. (Although his website is in German, the README file is written in English.) He suggests using the program Mobile Atlas Creator [9] (Figure 5), which can export suitable map packages for avNav. He has even made data with prepared map sources available for this program, making it possible for Mobile Atlas Creator to download the BHS vector maps.

Figure 5: Mobile Atlas Creator converts maps into a format that avNav can understand.

Mobile Atlas Creator is a Java application that runs without problem on the usual operation systems. Before starting the program for the first time, you should also download the directory with map sources from Vogel's website and copy them to the mapsources/ folder. This folder is created when you install Mobile Atlas Creator.

Once started, the program asks for the target format for exporting maps, and you should select the format from the Osmdroid GEMF list. The list of map sources is found at the upper left of the main application window. BSH OpenSeaMap 2014 Extended combines maps from BSH with those from OpenSeaMap and is well suited for the German coastline.

Using Mobile Atlas Creator can be somewhat tricky. The program distinguishes between zoom and scroll mode. The arrow keys on the keyboard are suitable for operating in both modes, but other functions are available depending on the mode. Zoom mode lets you enlarge or reduce the size of the section of a map currently displayed in the map window. However, you have to scroll before finding the area for display. A simple click on the map is all that is needed to switch between modes.

The program is tricky primarily because the mouse cursor cannot be used for scrolling. Instead, the cursor is only used in the map window to define the area that Mobile Atlas Creator is to export as a map.

Setting Up a Map

As soon as you have selected the correct area from a map, it is time to click to the left on Zoom Levels to choose the level of detail at which the map is displayed on the boat. Zoom levels 10 to 16 represent a good compromise between map content and an exact display.

Once a suitable area of the map has been selected and the zoom level is specified, you only need to left-click on Add selection to save. At this point, you should also change the name of the map with a right click on Unnamed atlas. The map will then appear in avNav with the new label. A click on Atlas | Create Atlas ends the process.

If the map servers are not the fastest, creating an atlas can take several hours depending on the amount of material involved (Figure 6). Once the process is complete, a file appears in the atlases/ folder in the main folder with a name that ends in .geml. You should copy the file to the /data/avnav/charts/ folder on the Rasp Pi.

Figure 6: Given a slow server, it may take quite a while to set up the avNav maps.

Restarting avNav ends configuration. When the web interface is reopened, you will see that the maps just prepared are available for selection. If the boat is located in an area covered by the map, you immediately see your correct location.

Buy this article as PDF

Express-Checkout as PDF

Pages: 8

Price $2.95
(incl. VAT)

Buy Raspberry Pi Geek

Get it on Google Play

US / Canada

Get it on Google Play

UK / Australia

Related content

  • Maritime navigation with a Rasp Pi and OpenCPN

    The Raspberry Pi is ideally suited to serve as the basis for a low-cost navigation system. OpenCPN software and a GPS receiver are all you need to add.

  • Using the Raspberry Pi for a multimedia center on your boat

    Due to its diminutive size and minimal power needs, the Raspberry Pi works well as a multimedia center on boats or in RVs.

  • Welcome

    It is rumored that Thomas Edison tested thousands of filaments for an incandescent lamp before he produced the first commercially viable electric light bulb, and I imagine his is not a unique experience. Building mock-ups and working models exposes the weaknesses and strengths of a design, which prepares you to make a better version, then a better version, until you have found the right combination of materials, components, configuration, and cost.