[osg-users] convert GPS coordinates to local terrain coordinates

[Stephane DUGUET]

Hello,

 

I'm new on OSG scene.

Here is my issue:

I have a TXP terrain on which I know the local origin coordinates. This
coordinates are:

Longitude : -117.642222

Latitude : 33.094444

 

I now whant to know the local coordinates (within my TXP terrain) of a
know location (GPS cocordinate):

Longitude: -117.3636264412

Latitude: 33.2940335740

 

I use ElModel->convertLatLongHeightToXYZ to transform the goedesic
coordinates in caretsian ones. What I need now if to transform the
resulting coordinates according to the origin's location in order to
take care of my offset.

 

Any idea of how to perform this?

 

I tried the following:

 

 OriLongitude=-117.642222/*origin*/;

 OriLatitude=33.094444/*origin*/;

 OriAltitude=0;

 ElModel->convertLatLongHeightToXYZ (osg::DegreesToRadians(OriLatitude),

 osg::DegreesToRadians(OriLongitude), 

                                    OriAltitude,  

                                    oriX,  

                                    oriY,  

                                    oriZ );

 

 

ElModel->convertLatLongHeightToXYZ
(osg::DegreesToRadians(33.2940335740),

 
osg::DegreesToRadians(-117.3636264412),

                                    0,  

                                    x,  

                                    y,  

                                    z );

 

 

xl=-sin(OriLongitude)*(x-oriX)+ cos(OriLongitude)*(y-oriY);

yl=-sin(OriLatitude)*cos(OriLongitude)*(x-oriX)

  -sin(OriLatitude)*sin(OriLongitude)*(y-oriY)

  +cos(OriLatitude)*(z-oriZ);

zl=cos(OriLatitude)*cos(OriLongitude)*(x-oriX)

  +cos(OriLatitude)*sin(OriLongitude)*(y-oriY)

  +sin(OriLatitude)*(z-oriZ);

 

But I still cannot have good results.

I have some doubts about the "-" sign applied to the longitude for a
West direction.

 

Thanks for your help,

 

Best regards,

 

Stephane

 

 

 

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