USAPhotmaps

[aabiking ✓ supporter]

Is anyone using USAPhotomaps to convert there tracks to GPX data? When Importing the data from my Garmin to USAPhotomaps the tracks match up with the topos perfectly but I did submit one exported GPX file to this site but Trek sent a copy of it back to me ovelayed on a map and the trail was out in the lake. It did not look like that in USAPhotomaps. I was just wondering if anyone else has tried this program and had the same results.

[Jeff Barber]

Ahhh, now I think I understand your original question a bit better

So it turns out that GPS data is never entirely accurate. I mean, first off the accuracy of your GPS depends on the strength of the satellite signal you’re receiving which depends on stuff like cloud cover, trees, time of day, etc. It is not unusual to find your position to be off by 100-200 feet for some parts of a ride. This could be putting you in the lake

Secondly, the maps themselves can be "off." Many times I’ve been riding a lakeside trail with a mapping GPS and according to the map I’m in the lake, even though I’m 100 yards away. The same goes for mapping software; we use ArcGIS and the base map package is not nearly pixel accurate, especially at smaller scales (like those used for bike maps). In general the data sources used to create map software aren’t the same – that’s why USAPhotoMaps may look different from the maps on singletracks or Google Earth, etc.

So don’t worry if a trail goes into the lake a bit on your map – as long as you’re in the vicinity everything is normal.

[aabiking ✓ supporter]

It looks fine on my map. It was on the map file that you sent me. I will e-mail you the GPX file tonight and also a .jpg of the track in USAPhotomaps so you can compare.

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