RunningAHEAD - Topic: Upload Map Data correct for mileage, but Summary info INCORRECT

palomares05

posted: 7/31/2010 at 8:30 AM

GRRRR so frustrated. I went for a jog this morning, and I have it mapped and it is according to all other maps roughly 3.6 miles. When I stopped jogging this morning, my screen showed 4.21 miles, and that is what it uploaded. However when I click on the map section, it shows that I jogged 3.62 miles...

So my question is, why in the world does the map show the correct mileage, but not the actual workout summary. I have edited the summary now to reflect the correct information, but of course my splits are off now...

Any suggestions?? Ideas???

I am using Motorolo Cliq XT Android 1.5 based

derek

posted: 7/31/2010 at 8:55 AM

Quote from palomares05 on 7/31/2010 at 8:30 AM:

I am using Motorolo Cliq XT Android 1.5 based

Seeing that you mentioned "Android", are you referring to the HandyRunner app? Or is this unrelated?

Derek

Derek

palomares05

posted: 7/31/2010 at 1:15 PM

Yes I am using the Handy Runner app. The map mileage is spot on...but the workout mileage said 4.21 ...any ideas?

eric :)

posted: 7/31/2010 at 1:33 PM

palomares05,
Phone based GPSs are not very accurate. If you zoom in on your map, you'll see your path to be very jagged. There are spots where you seem to backtrack. I'm pretty sure this isn't the case. They are artifacts of GPS inaccuracy. Here's a map from a Garmin Forerunner. Although it's still not precise, notice the path is rather smooth compared to your route.

RA, like most other mapping sites, uses Google maps to display the route. If the map contains many data points, it gets very slow. In an attempt to speed it up, some of the non-relevant points are pruned before the map is rendered. This means that the entire route is smoothed out, resulting in some distance reduction. This is what you observed. However, the distance is altered for display only. The actual distance is still 4.21, although I suspect this is not entirely accurate either due to the apparent zigzagging.

derek

posted: 8/1/2010 at 8:25 AM

Quote from palomares05 on 7/31/2010 at 1:15 PM:

Yes I am using the Handy Runner app. The map mileage is spot on...but the workout mileage said 4.21 ...any ideas?

As Eric pointed out, it all has to do with *how* the GPS data is analyzed. I know for a fact that my app probably needs some better data smoothing algorithms, but I would readily admit that is probably out of league. I may try and look into it more in depth at some point in the future, but that isn't a high priority for me.

Derek

Upload Map Data correct for mileage, but Summary info INCORRECT (Read 463 times)