[Gta04-owner] Advance OpenStreetMap surveying with GTA04? / compass

Mayeul Kauffmann mayeul.kauffmann at free.fr
Sun Mar 18 22:47:06 CET 2012


Hi Ed,
Thanks for the explanation on "course"!

GPS-based heading is good for car driving and OK for road biking, not
for slow travels:
Position error jumps a few meters every seconds, hence if you do not
move, the GPSr believes you move at 1 to 4 km per hour in random
directions.
So GPS-based heading must be taken with care for mountain biking and
extreme care for hiking.
Here I need to know the heading of a picture. Typical uses are:

Example 1: stay in the middle of a path or track junction; take 4
pictures, in each of the directions of the 4 paths or tracks; mark the 4
ways on OSM with the way path, width, etc.
Example 2: take pictures of signpost, side shrine etc. and remember on
which side of the track they are.

You need a compass heading for this. If current compass heading can be
recorded with a bash command I can do the rest, typically develop a GUI
that will send, at the send time, the command to save the compass
heading and the command to take the picture (then with 'sed' I filter
the heading/positions and write it into the jpeg image header with
jhead).
(Except that Nikolaus Schaller from goldelico says the camera driver is
not working for the moment)

Cheers,
Mayeul

Le dimanche 18 mars 2012 à 21:43 +0100, Ed Kapitein a écrit :

> Hi Mayeul,
> 
> course is the same as heading.
> http://en.wikipedia.org/wiki/Course_%28navigation%29
> So all the ingredients are there for successful logging!
> 
> As for orientation, it depends on what you mean, course is your
> orientation towards the north.
> And the accelerometer provides orientation towards the earths surface,
> but i never used it myself.
> 
> Kind regards,
> Ed
> 
> 
> 
> On 03/18/2012 06:39 PM, Mayeul Kauffmann wrote:
> > Thanks a lot ed!
> > Having a gpx extract is great (I'm currently playing with it).
> > Yes, 'hdop', 'fix' and 'sat' are the 3 main fields I need for precision.
> > What is "course"? I found "Instantaneous course at the point" (in
> > degrees) [1] but I do not understand.
> >
> > Anybody could confirm that GTA04 gives this as well? (I've just asked
> > the gta04-owner list too). Also: What about orientation?
> > Thanks!
> > Mayeul
> >
> >
> > [1] http://www.topografix.com/gpx_manual.asp#course
> >
> >
> > Le dimanche 18 mars 2012 à 17:57 +0100, Ed Kapitein a écrit :
> >> On 03/18/2012 02:25 PM, Mayeul Kauffmann wrote:
> >>> Le dimanche 18 mars 2012 à 14:34 +0200, Timo Juhani Lindfors a écrit :
> >>>
> >>>> I used another GTA02 to make audio notes and a cheap and small digital
> >>>> camera to take photos. As long as all clocks are synchronized you can
> >>>> combine all the data with your netbook later.
> >>> Thanks a lot Timo! I already do this with my Garmin and gpscorrelate
> >>> (GNU/GPL), but without HDOP nor heading.
> >>> Can you save the HDOP [1] with the GTA02?
> >>> Do you have access to heading in the command line (with possibility to
> >>> pipe it)?
> >>>
> >>> Thanks!
> >>> Mayeul
> >>>
> >>> [1] http://en.wikipedia.org/wiki/Dilution_of_precision_%28GPS%29
> >> Hi Mayeul,
> >>
> >> If, on  a GTA02, you use a nmea log  and gpsbabel to translate it to gpx
> >> format, you get:
> >>
> >> <trkpt lat="51.987431167" lon="4.337932667">
> >>   <ele>-16.800000</ele>
> >>   <time>2012-03-17T14:01:21Z</time>
> >>   <course>61.230000</course>
> >>   <speed>1.071073</speed>
> >>   <fix>3d</fix>
> >>   <sat>8</sat>
> >>   <hdop>1.580000</hdop>
> >>   <vdop>2.140000</vdop>
> >>   <pdop>2.660000</pdop>
> >> </trkpt>
> >>
> >> Would that give you all the info you need? HDOP and course  are present.
> >> ( the above is just one sample of a track i walked yesterday, with a GTA02 )
> >>
> >
> >
> >
> 


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