Salut
Damien
I am not sure If I have understood your question, but I think you are
asking about differences in direction from the QtSensors Compass and
the the QtPositioning PostionSource elements.
1) The Compass Azimuth shows the direction the top of the device is
pointing to (so it will change as your rotate the device).
2) The PositionSource shows a direction based on the direction the
device is travelling (irrespective of where the device is pointing).
http://qt-project.org/doc/qt-5/qgeopositioninfo.html
Similar to 2) The speed shown by a GPS is absolute, irrespective of
how the device is pointing. Some years ago I was coastal soaring on
the coast of South Africa when the wind picked up, and got to the
point where it was at (and possibly just above) the maximum speed of
my paraglider. Flying fully into the wind, pushing maximum speedbar
the GPS was showing speeds of 0.5 - 1 Km, and it was very difficult to
tell if this was fowrards or backwards - but it was most likely the
latter.
Cheers
Chris
Zitat von "Caliste Damien" <dcali...@free.fr>:
Bonsoir,
Le dimanche 12 janvier 2014, christopher.l...@thurweb.ch a écrit :
Marcel used the Compass element from QtSensors for azimuth.
Ok, I understand, but I'm still wondering :
- QtSensors and compas will provide the azimuth of the device, so
acting it like a compas, for instance, top of the device is pointing to
the north.
- QGeoPosition is providing GPS info with latitude and longitude, and I
was thinking that the direction attribute was in fact the first
derivative of the position, which is different from the compas return
value, for instance I'm moving west while pointing top of device to the
north.
So how to get the first derivative of GPS position, deriving it by
hand ? Like calling the azimuth method on the two last GPS fix ?
Have a nice week,
Damien.
_______________________________________________
SailfishOS.org Devel mailing list
