what do those numbers mean...

Discussion about GPS Log for iOS, it's features and uses.

what do those numbers mean...

Postby niconiko » Sat Jun 18, 2011 4:40 pm

Hi, new user here.

In the "Location" box, I understand the position co-ordinates, and assume the xxx m. figure in bold represents altitude. But, on the left side in a smaller font-size is a pair of xxx m. figures, one above the other. What do those represent?

Thanks.

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Re: what do those numbers mean...

Postby divzero » Sat Jun 18, 2011 10:02 pm

Hey niconiko, welcome to the forums!

I'm sorry for the confusion. Allow me to explain the settings:

example:

100m(1) 31.134111, 121.312456(2)
190m(3) 4m(4)


(1) this is the gps accuracy of the coordinate, not the altitude. 100m means that iOS thinks that the gps position is accurate ±100m. Of course, it is possible that this is not always accurate itself! But it's a pretty fair guide. 5-30m is good. 30-100m average, > 100m not great.

(2) this is latitude and longitude in decimal degrees.

(3) this is the accuracy of the altitude. so with this example iOS things that the altitude is correct to ± 190m.

(4) this is the actual altitude itself.

Note that by default, (3) and (4) are hidden. I assume you enabled the altitude display in the settings?



Does my explanation help? I understand it is a little confusing to new users, especially with the altitude. I have considered adding a '±' to the accuracy values to help get across the message that these are the accuracy. Do you think that would be a good idea?

E.g. it could look like:
±47m 54.245523,-42.242552

Would that have been clearer for you?

Cheers,
Will
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Re: what do those numbers mean...

Postby niconiko » Sun Jun 19, 2011 11:23 am

Will, thanks for the detailed explanation. I understand it now. And yes, adding a +- char could help.

While I have you on the line, there's some other display data unclear to me. In the GPS log, to the right of a spike's title are a date and a xxx m. figure. What is that m. figure about? It seems to be the distance from the bottom-most spike.

And speaking of the GPS log list of spikes, it'd be helpful if it had sort-settings. It seems now there's only a by-date sort, but I'd prefer a by-title sort.

Still, very satisfied with GPS Log. The Geospike website on the other hand... ¬_¬

Cheers.

--
Nicolas Cueto
Motegi (Japan)

niconiko
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Re: what do those numbers mean...

Postby divzero » Sun Jun 19, 2011 1:28 pm

niconiko wrote:Will, thanks for the detailed explanation. I understand it now. And yes, adding a +- char could help.


I'll consider changing this, I think it does make sense…

While I have you on the line, there's some other display data unclear to me. In the GPS log, to the right of a spike's title are a date and a xxx m. figure. What is that m. figure about? It seems to be the distance from the bottom-most spike.


That is the distance to the spike from your current location. It's the straight-line distance (a.k.a "as the crow flies"), and doesn't take into the terrain in between, so the actual distance is normally longer. If you see a "~" symbol in front of this distance, it means that the distance calculation contains a large amount of error (due to the GPS accuracy) and may be significantly closer or further than stated.

You can also see this distance if you view the map of a particular spike. Can be useful when you are trying to re-find something you spike. Or a location you've never been to that you entered manually. When viewing these distances, the error margin (indicated by the ~ on the main list) is stated in meters. For example 7m ±157m means the GPS thinks you are 7m away, but the combined error is 157m so you should look around and try to locate the spike with your eyes :)

And speaking of the GPS log list of spikes, it'd be helpful if it had sort-settings. It seems now there's only a by-date sort, but I'd prefer a by-title sort.


Good suggestion. Want this in the App or at Geospike.com?

Still, very satisfied with GPS Log. The Geospike website on the other hand... ¬_¬


Thanks! I understand your concern with the website. GPS Log has been in development since December 2008, while Geospike only since late in 2010. Rest assured we are working hard at it, and hope by this time next year it will be a very solid web-app that you find convenient and easy to use. Thanks for your patience while we build it! Thanks for your feedback, it is always welcome.

Cheers,
Will
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Re: what do those numbers mean...

Postby niconiko » Sun Jun 19, 2011 9:22 pm

Good suggestion. Want this in the App or at Geospike.com?


Definitely on the App.

GPS Log has been in development since December 2008, while Geospike only since late in 2010. Rest assured we are working hard at it


Resting assured then :)

Cheers.

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