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Generating Google Maps files from GPS data – Part 2

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previously discussed my method for generating Google Maps files with a single click. Since then I have made some modifications to my GPSBabel XCSV style file. The best way to highlight these changes is to view a sample map generated with this process.

Some of the changes include:

  • Date and time for start and end points for each day
  • Altitude for start and end points for each day
  • Maximum () and minimum () altitude for each day
  • Distance traveled in a given day – shown in the end marker balloon
  • Total trip distance traveled for all days – shown in info panel
  • Button to show/hide the track lines – in case you want to see the name of a road, for example
  • Button to show/hide an info panel in the lower right corner with total trip distance and coordinates of mouse/last click

Initially, the Google Maps HTML files I was getting from multi-day tracks were way too big and were basically grinding my browser to a halt. I used the GPSBabel simplify filter to remove extra data points which greatly reduced the resulting file size and increased performance significantly. The filter was applied as shown below:

gpsbabel.exe -i gpx -f infile.gpx -x simplify,crosstrack,error=3.0m -o xcsv,style=google_maps.style -F outfile.html

Finding the total distance across multiple days ended up being a lot easier than I expected, thanks to a function in the Google Maps API, which resulted in this code:

var total_miles = 0;
var miles = poly[z].getLength() * 0.000621371192;
total_miles = total_miles + miles;

All of the changes are available in the updated zip file available here. I’m having additional discussions about this GPS datalogger and my workflow over on the GpsPasSion forums (starting on page two).

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