I'm really not understanding how to go with this...
I've been reading and reading.. I can find all kind of algorithms.. I
can find a haversin algorithm that points me to the correct direction
if my device is pointing north.. but the needle is static... so if i
change the device orientation the measure is incorrect... and I know
this happens because I'm not using device's sensor values like
azimuth, pitch and roll.. oh god.. 2 weeks on this.. I'm just
desperate now.
On Sep 18, 2010, at 10:29 AM, Kostya Vasilyev wrote:
Pedro,
If I understand you correctly, you are having difficulties with the
device's orientation.
The bearing angle seems to be computed in the horizontal plane. If
you wish to adjust for the device's orientation, you need to
concatenate it with the bearing angle.
Google for "quaternions".
This is a (relatively) simple math technique to work with rotations
the same way you can work with vectors: add / subtract, interpolate.
-- Kostya
18.09.2010 0:56, Pedro Teixeira пишет:
Hi everyone...
I'm back with the same issue for the last couple of days… I'm
trying
to create a compass for my application BUT the difference is that,
instead of having a line always pointing to north, I want this line
to
point for a specific point. I've been trying dozens of algorithms and
nothing works..
I've finally found one that points me exactlly to the point I want..
BUT it doesn't move if I change the position of the device which is
my
objective.. basicly, what I want is that no matter the direction I'm
using my device.. the line always point me to the point
(picLatitude,picLongitude)…
I understood that for the line to move, I can't use static
variables…
I need to use the values offered by the onSensorChanged(SensorEvent
event).
This are the data I have available:
event.values[0]: azimuth, rotation around the Z axis (device in
relation to north, 0º)
event.values[1]: pitch, rotation around the X axis
event.values[2]: roll, rotation around the Y axis
mLatitude: device current latitude gottern from GPS (variable)
mLongitude: device current longitude gotten from GPS (variable)
picLatitude: static picture latitude established previously
picLongitude: static picture longitude established previously
distance: distance in Km from device to the picture calculated
previously
And this the formula that works correct, and gives me the correct
angle.. ( BUT IT DOESN'T USE ANY OF THE SENSOR DATA SO THE LINE
COMPASS DOESNT MOVE):
double dLong = picLongitude - mLongitude;
double y = (Math.sin(dLong) * Math.cos(picLatitude));
double x = (Math.cos(mLatitude) * Math.sin(picLatitude) -
Math.sin(mLatitude)*Math.cos(picLatitude)*Math.cos(dLong));
double angleDegreesWrongRange = Math.abs(Math.toDegrees(Math.atan2(y,
x)));
float angleDegrees = (float) ((angleDegreesWrongRange+360) % 360);
myCompass.updateDirection(angleDegrees);
I got this "bearing" formula from this website:
http://www.movable-type.co.uk/scripts/latlong.html
Can someone please help me with this?
I've try adding, subtracting… the azimuth.. I've tried with the
others.. seriously at this point I'm just demoralized..
Thank you in advance
--
Kostya Vasilyev -- WiFi Manager + pretty widget -- http://kmansoft.wordpress.com
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Pedro Teixeira
www.pedroteixeira.org
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