- Questo topic ha 14 risposte, 2 partecipanti ed è stato aggiornato l'ultima volta 12 anni, 8 mesi fa da
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I was wondering if there is a way to adjust the way distances are displayed. I have noticed on switching over to WP GPX Maps from the inferior XML Google Maps that all my tracks now seem longer. I see from another post that you have used http://utrack.crempa.net/ to base distances with and I have verified that the distances WP GPX Maps displays, matches utracks estimates. However, when I load the exact same GPX into google maps, the distances are a lot different. A track I have in WP GPX Maps displays as 33.9 miles while it is only 29.8 in Google maps. That’s a big difference. I see utrack calculates distances based on elevation by “Calculating flat and real distance (real distance contains information about changing elevation so it is more accurate”. The recorded elevation of gpx track’s from my cell phone are not too accurate. I think this throws the calculated distance way off. Is there a way to display flat distance so my tracks appear more accurate? If this has been answered before, I apologize. I couldn’t find a search function in your forum to query.
So this can’t be adjusted?
Hi, I think taking distance without considering the elevation (like other plugins) is quite wrong..
I made a lot of work to get the distance the as accurate as possible. Also http://utrack.crempa.net/ confirm my work:
http://utrack.crempa.net/report/saved_report.php?ident=2e0fb29b6643129d15257c1ce6716c24&lang=enThanks for the response. I kindly disagree about the distance thing. My cell phone app does not record elevation very acurately so it makes the caclulated distances way off. I think you should program your plugin to measure both ways and give the end user a choice. Thanks you for your time. I’ll be using the other plugin for now.
Hi,
It is pretty interesting, I just checked a GPX file from a yesterday ride that I recorded with GPS KIT for iOS. Though I have no idea how GPS KIT collects altitude information the track itself is 5-10m accurate.
GPS KIT : 44.560m
GPS Visualizer: 44.712m
Google Earth: 43.500m
MotionX GPS HD: 44.567m
utrack total flat distance: 44.700m
utrack total real distance: 48.600m
and
WP GPX MAPS: 48.546mWould it mean that all the services including Google Earth measure distance without elevation?
Or different services use different altitude data charts when calculating distance? Would somebody please explain it? Flat, real distance?Thanks.
There are a lot of algorithm to get distance between 2 gps points, some of them are fast and others are precise.
If you want to get the precise value you have to consider altitude/longitude/latitude/bearing.
Here a very good page with a sample of some algorithm:
http://www.movable-type.co.uk/scripts/latlong.htmlGenerally some meters are lost becouse of mathematical approximation, because there is a sum of a lot of small values..
I realized that a lot of programs are not considering altitude at all! This is a big lack in my opinion!Thanks for the clarification, though its Chinese for me.
I believe your calculation as precise is it could get.
Does setting the offset and reducing GPX points effect the total distance in this case or your plugin run the math before those calculations?Yes if you have a lot of turns this will effect the total distance, this is an exaggerated sample of approximation
This curve will approximated like this
more point you have more accurate will be the total distance..Hi again,
I made a “test” again and my conclusion is that utrack and therefore WP GPX MAPS distance calculations are off.
This time I measured my MTB ride with a bike computer as well, which is the most accurate device for cyclist for distance/average speed/max speed data.Bike computer: 69.587m
GPS Kit for iPhone: 69.780m
Google Earth GPS import (not adjusted to ground height): 68.200m
GPS Visualizer (no waypoint reduction): 69.202m
GPS Visualizer (modified elevation data from best source, no waypoint reduction): 67.700 [this is off, as the highest peak I reached is 728m and not 702m]utrack and WP GPX MAPS with no waypoint reduction: 75.955m
As you can see the original GPX data shows 200m plus compared to the bike computer – but I had to bring the bike on my shoulder at times, so it is highly accurate. GPS Visualizer with no waypoint reduction is pretty close and shows only 300m difference, I consider this accurate as well, while GE – which reduces waypoints – shows 1300m difference, which is tolerable I guess.
But utrack and WP GPX MAPS shows 6000m difference, in other words 10% more than the distance traveled.
Don’t get me wrong, I like your plugin but something has to be done. When dealing with numeric data 10% difference (with the previous GPX file, and with Jay Thompson’s file too) is not considered accurate, close nor informative result.
My suggestion would that as most GPS receivers and smartphones do record altitude information there should be a “Use original GPX data source” checkbox. With this toggle the plugin should only format and parse the source XML data (and if checked skip waypoints) and would plot that to the map/chart/summary.
What do you think? The above suggestion would help folks like me to get more accurate data? How could I help?
Thanks.
Hi. I see you’ve been updating the app lately so I thought I would check in. I still want to use your app but I want to be able turn off the distance adjustments and use the standard distance like the “other apps” you disagree with. Respectfully considering your opinion, please consider making this an option. More options for the end user is better!
Thank you for the hard work. :good:
Other guys asked a graph for the climb distance, I think I can add a “flat distance” and a “climb distance”
Oh thank you, thank you! That would be awesome! :yahoo:
I too would like to see an option to use the original gpx data for calculations as well as your way of calculating them. Changing the setting to flat distance changes that data point, but the average speed doesn’t change along with it, as it should when the distance drops from 6.09 to 5.69 miles.
Here is the original data showing on the BackCountry Navigator PRO v5.2.1 app on my android phone, where I exported the gpx file from:
Total distance: 5.7 mi
Max elevation: 153 ft
Min elevation: -42 ft
Total climbing: 588 ft
Total descent: not provided
Average speed: 2.7 mi/h
Total Time: 02:08:26And here is data showing up from your wordpress plugin:
Total distance: 6.09 mi
Max elevation: 197 ft
Min elevation: -108 ft
Total climbing: 4505 ft
Total descent: -4409 ft
Average speed: 3.48 mi/h
Total Time: 02:08:24So I am also interested in how your plugin is calculating elevations as those seem to have a huge difference as well.
I really do love this app though, very intuitive compared to others I have tested, and it looks great!
