How far did I actually run?

Someone asked “is it possible to show the total distance run by a competitor based on the input of an individual’s route”.
The answer is a bit complicated but possible.

The length of the actual route plotted is shown in pixels, so you can compare it with others.

But the problem is that the map scale is not fixed/defined in RG. It is only a JPG image (bitmap) of the map, and it depends on what DPI (dots per inch) was chosen for the export from Ocad. The reasons why a particular dpi is chosen is down to ignorance of what to choose, luck or calculated choice based on the level of detail of the map that need to be resolved.
So there is no relationship of pixels to lat/lon to base a calculation on.

You can calculate it yourself by doing a screenshot of the map at the default zoom level (when you first load an event), then crop the image to a section between grid lines (which should be 250mtrs apart) and see how many pixels wide the image is then multiply by 4 to get the number of pixels per km. The image here is 201 pixels wide, but includes a bit extra so you can see the grid lines, so lets say it’s 200 pixels for 250mtrs X 4 = 800 pixels per kilometre. So in the example of Simon Bradbury at the British nights, 7385 pixels total plotted route:
7385 / 800 = 9.23k
The control description said the course was 8.4k (according to my GPS, I did 12.24k, but i took some scenic routes!)

18th Feb 11

Comments or questions

OMM 2011 Conversion

I have just done this for the OMM 2011 Medium Score Day 1 map, and there are 100 pixels per square. (I guess the other maps will be the same).

In this case, a square is 1 km, so the conversion is 10m per pixel.  Hope that helps.

Posted by Jell Ellis on 31st Oct 11

The straight line course is input.  If we were told the number of pixels this is, could we not calculate the distance we ran by scaling our pixels to this length, as we are told the length of the course?

Posted by John Duffield on 14th Nov 11

The problem, is that RG doesn’t calculate the pixel length of the connecting lines.

Posted by Admin on 14th Nov 11
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