Hi,
On 02/04/11 19:09, Brett wrote:
Hi,
I was wondering if any of the equations or libraries used with osg or
vpb allow the user to perform site calibration / localization for RTK
GPS. ie. I am trying to create a transform to convert WGS84 coordinates
into a local Cartesian coordinate system based on matching 3 or more GPS
survey points with locally defined / measured points. The local points
are in a localized 'flat' coordinate system. This may require
calculating a local 'datum' using something like a Molodensky or
Bursa-Wolf transform. I am looking for information to develop these
equations or some open-source software to perform this calculation. Any
help or advice is greatly appreciated. Thanks in advance.
OSG's EllipsoidModel can do some of this for you. See:
computeLocalToWorldTransformFromLatLongHeight
Basically you create a transform like this for a reference lat/long/alt
point. This transform puts LLA points into a coordinate system on a
"local tangent plane" (google this) at the reference point. In the local
system you can then align your device axes/coordinate system to the
reference axes/coordinate system by using multiple points and some
optimisation algorithm.
So, in one direction you go from LLA -> ECEF -> local coords -> device
coords.
cheers
jp
Brett
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