Using the ride-tribe route profiler is easy. Using the map, navigate to wherever in the world you want to plot your route. Then click on the Start/Continue Line button under the map. You can plot your route by clicking on the map to place points on the map along your route. To finish the route, simply click on the final point on your route.
You can extend your route either by clicking on the Start/Continue Line button or by clicking anywhere on the line other than any of the points on it. You can then add points to the end of the line.
You can delete a point on your line any time that you are not plotting the route. Simply click on any point on the route to delete it. The tool will redraw the route as a straight line between the two points adjacent to the point you have just deleted.
You can alter the path taken by your route by dragging any of the semi-transparent ghost points that exits in between the real points on the line. Doing this will create a new point on the line.
To start again with a completely new route, click on the Clear Map button.
To calculate the profile of the route, simply click on the Calculate Profile button. After a few seconds the profile information for the route will be displayed in a separate browser window. This includes a graphical representation of the altitude profile of the route and some vital statistics for the route including the two magical numbers that all mountain bikers are interested in; the cumulative ascent and descent of the route.
You can get a print out of the route profile information displayed by clicking on the Print Profile button at the bottom of the popup window.
Here's some supplementary information about the ride-tribe route profiler for all you eggheads out there.
The core of the tool is, of course, Google Maps. The altitude information comes courtesy of our good friends at topocoding.com. The tool sends to the topocoding.com server the exact positions on the earth of all points on the line that you have plotted. What is returned is the altitude, in metres above mean sea level, for each point.
The altitude data is sourced from none other than the National Aeronautics and Space Administration (NASA). The good fellows at NASA mapped the majority of the Earth's land surface in 90x90 metre squares during an 11 day mission of the Space Shuttle Endeavour in February 2000. The result is the Shuttle Radar Topography Mission (SRTM) data set.
The chart is produced with the incalculable help of the true geekmasters of the world at Google and their Charts API.
A couple of things to keep in mind when using this tool. Firstly, as mentioned above, the SRTM data set considers the world's land mass as made up of a lattice of 90x90 metre squares, with one altitude number for each square. That's okay for most places. But in areas of particularly steep terrain, you might notice some odd results coming out when you display the route profile.
The SRTM altitude data set is not accurate, or is indeed missing, in glacial or snow-covered high mountain tops.
The calculation of route distance is made on the assumption that the world is a perfect sphere. But the world isn't a perfect sphere. As a result of the fact that the world rotates around itself, it bulges at the equator and is flattened at the poles. Thus the distance of the route as displayed could be in error by as much as 0.3%, especially in polar regions. Good enough for most purposes, but please bear this in mind if you intend on using the tool to plan an expedition to the South Pole. Oh that and also due to the fact that Antartica isn't covered by the SRTM data set.
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