Hdop and accuracy value, explanation

Kozlov Aleksey shared this question 48 days ago
Answered

Hi!

What does hdop field in .gpx file recorded by Locus mean? And how can I calculate GPS accuracy in meters from it?

Comments (6)

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I did some testing and got that Locus writes accuracy in meters as hdop value. Then I googled a little and as I understand this is not correct.

Could you give me more understanding about what is written by Locus in hdop field please?

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Hello,

hdop field in the GPX file should match the "accuracy" value returned by the Android system itself. Its description is wrote here: https://developer.android.com/reference/android/location/Location.html#getAccuracy() .

Hope this helps.

Jiří M. aka Menion

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Hi Menion,

thank you for the answer.

According to https://www.topografix.com/GPX/1/1/#type_trksegType hdop value should contain Horizontal dilution of precision. It's something different than accuracy provided by android.location.Location. See https://en.wikipedia.org/wiki/Dilution_of_precision_(navigation)


Are there any plans to change this behavior of Locus?

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Hello,

there are currently no plans for change. Do you have any idea how to even convert these two values?

Jiří M. aka Menion

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No idea :)

My first question was exactly about the same but only about opposite conversion direction.

Until I realized that what I need is exactly what is written to hdop by Locus.

But now the question is - do all the devices/apps over the world act the same way as Locus? :))

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Hmm, how other apps works > no idea.

But "accuracy" received by Locus Map over the "Location" object is what definitely use all apps.

The only idea, how this may be improved, is to read NMEA messages and extract HDOP value from these messages. Or, if you have any usage for this value, feel free to recompute it on your own ;).

Menion