Free Geography Tools

I posted version 1.0 of my utility TritonRMP Helper on this site a few weeks ago, an aid to creating custom raster maps for the Magellan Triton GPS series. It re-projects a GeoTiff to geographic/WGS84 coordinates (if necessary), then extracts out the calibration data needed by the program TritonRMP Maker to convert the TIFF file into a Triton-compatible RMP file. I’ve added a few enhancements to it, and voila, version 2.0. Check the original post for basic info, but here are the improvements:

• The biggest change is in exporting calibration data to TritonRMP Maker. In 1.0, you had to manually copy the coordinates of calibration points into the program. Version 2.0 of TritonRMP Helper now creates a “gmap” file containing all the calibration data needed by TritonRMP Maker; no more manual copy-and-paste required, which cuts the time and work required a lot. Load the gmap file into the Maker program with the File => Map => Import Maps command. You can load multiple gmap files at the same time to combine maps, or different zoom levels, in the final RMP output. The name of the gmap file is displayed at the top of the program, along with the GeoTiff file associated with the calibration data:

• Version 1.0 allows rescaling of GeoTiff images down to smaller sizes, for use at lower zoom levels, but this sometimes fails without warning for very large images. Version 2.0 checks for this failure, and gives you an error message. You can sometimes get the rescaling to work by exiting the program, then starting it up and trying again.
• Version 1.0 came with no install program, just a zipped folder containing the executable and associated files. Some people were reporting issues with the “comdlg32.ocx” ActiveX control being missing on their system, and some would probably prefer to have a regular program install. So the program is now available in two versions: an executable for a full install, and a zipped folder version for those who don’t want the full install.

Standard disclaimer, i.e. use it at your own risk, and double-check any maps you produce for accuracy. And report any bugs you find to me via my Contact link.

For a while, there were two programs you could use to calibrate and convert raster map images into Magellan-Triton-GPS-compatible maps, TritonRMP Maker and RMP Creator (website in German). The author of RMP Creator apparently decided to remove the custom map calibration and conversion functions in favor of those in TritonRMP Maker, but did keep the program active for one very cool function: converting rasterized Open Source Mapping (OSM) data into Triton-compatible map formats.

It’s a Java WebStart program; here’s a direct link to the program launcher. Run the program, and zoom in to your desired geographic area:

Based on the map zoom level, the program will automatically choose which output zoom levels will be available, and you can select/deselect them by checking the boxes at the bottom. You have the choice of basic OSM street maps as above, or the OSM Cycle Map which includes topographic contours:

Specify the output filename in the ResultFiles box, click on the “Execute Conversion” button, then wait a while as the program downloads map tiles for multiple zoom levels, combines them, and converts them to a single RMP file for use in the Triton GPS unit. Once completed, you can install the map file into your Triton with Vantage Point, or copy it directly to the Map_data folder on the SD card used with the Triton. They’re not vector-map sharp, but do show streets and street names clearly enough:

The Magellan Triton 2000 GPS receiver I’ve reviewed in previous posts (one, two), and other similar units in the Triton series (the 400, 500 and 1500), are notable for their ability to display raster imagery like topographic maps and aerial photos. When first released, this was only available through the National Geographic Topo! software, which was expensive, buggy, and not very easy to use. While the National Geographic Topo! software has supposedly been improved, you’re still limited to their maps for upload to the Triton units, and they’re still expensive. And until recenlty, there was no ability to add maps of your own imagery to these GPS units. If National Geographic Topo maps were the only option for putting raster maps on the Triton GPS units, there wouldn’t be a compelling reason to buy them.

Fortunately, Mikhail Sharonov managed to reverse-engineer the format for these raster maps, and has released a free utility called TritonRMP maker that lets you create your own custom raster map files for use in Triton series GPS units. It’s a stand-alone program with no install required, just unzip it to the folder of your choice and run it:

If you own the popular GPS program OziExplorer, and have used it to calibrate map images, you can import those maps and calibration data directly into TritonRMP. If not, you can open map images in one of 18 different formats, either downloaded directly or created in the GIS program of your choice, then use the built-in calibration facility to georeference the image by:

1. Clicking on one of the colored calibration tab icons in the window at right
2. Double-clicking on a known location in the map window to place the icon there
3. Entering the geographic position for that location in the lower right
4. Repeating the process for at least one more point, with the option for three more points
5. Clicking the “Calibrate” button to calibrate the image

TritonRMP Maker automatically sets the zoom levels at which the map becomes visible/invisible based on the geographic size of the pixel. You can add additional images to the mapset that will show up at different zoom levels; for example, you could add and separately calibrate 1:250K, 1:100K and 1:24K topographic maps, and have the appropriate scale map show up at an appropriate zoom level on your GPS unit. When all maps are added and calibrated, use the Create RMP function to generate a raster map file for the Triton in the RMP file format; the name you save it under is the name it will have in the Triton. When the map generation process is complete, you could add the map to Magellan’s Vantage Point software and use that to upload it to your Triton GPS using the USB 1.1. interface (12 Mbps). But it will be easier and faster to stick your Triton’s SD card into a high-speed USB 2.0 reader (480 Mbps), and copy the RMP map file directly into the Map_Data directory on the SD card; when you replace the SD card back in the Triton, this new map will show up in the map selection screen where you can select it for viewing.

TritonRMP Maker is neat, fast and simple to use, but does have several drawbacks:

• For the best calibration results, the map should be in geographic projection (latitude/longitude); many maps are likely to be in some variant of the Mercator projection, like UTM.
• Many map files, like GeoTiffs, come with georeferencing infomation already embedded in them, and it seems like a waste of time to have to re-calibrate them in TritonRMP Maker.

For GeoTiffs, I’ve written a small utility program that will help with both of these issues; that’s tomorrow’s post.