From Paul Martz, with a couple of mods by Robert Osfield:

"Changes to return the lat/long origin of an
OpenFlight model as userData of the root node object."

include/osgSim/GeographicLocation

@@ -0,0 +1,87 @@
+/* -*-c++-*- OpenSceneGraph - Copyright (C) 1998-2004 Robert Osfield 
+ *
+ * This library is open source and may be redistributed and/or modified under  
+ * the terms of the OpenSceneGraph Public License (OSGPL) version 0.0 or 
+ * (at your option) any later version.  The full license is in LICENSE file
+ * included with this distribution, and on the openscenegraph.org website.
+ * 
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the 
+ * OpenSceneGraph Public License for more details.
+*/
+
+#ifndef OSGSIM_GEOGRAPHICLOCATION
+#define OSGSIM_GEOGRAPHICLOCATION 1
+
+#include <osg/Math>
+#include <osg/Referenced>
+
+#include <ostream>
+
+namespace osgSim {
+
+/** Stores a double precision geographic location, latitude and longitude.
+    Derived from Referenced so it can be used as an osg::Object userData.
+*/
+
+class GeographicLocation : public osg::Referenced
+{
+    public:
+
+        GeographicLocation() { _v[0]=0.; _v[1]=0.; }
+        GeographicLocation( double lat, double lon ) { _v[0]=lat; _v[1]=lon; }
+
+        inline bool operator == ( const GeographicLocation& v) const { return _v[0]==v._v[0] && _v[1]==v._v[1]; }
+        inline bool operator != ( const GeographicLocation& v) const { return _v[0]!=v._v[0] || _v[1]!=v._v[1]; }
+        inline bool operator < ( const GeographicLocation& v) const
+        {
+            if (_v[0]<v._v[0]) return true;
+            else if (_v[0]>v._v[0]) return false;
+            else if (_v[1]<v._v[1]) return true;
+            else return false;
+        }
+
+        inline double* ptr() { return _v; }
+        inline const double* ptr() const { return _v; }
+
+        inline void set( double lat, double lon ) { _v[0]=lat; _v[1]=lon; }
+
+        inline double& latitude() { return _v[0]; }
+        inline double& longitude() { return _v[1]; }
+
+        inline double latitude() const { return _v[0]; }
+        inline double longitude() const { return _v[1]; }
+
+        inline bool valid() const { return !isNaN(); }
+        inline bool isNaN() const { return osg::isNaN(_v[0]) || osg::isNaN(_v[1]); }
+
+        /// binary vector add
+        inline const GeographicLocation operator+( const GeographicLocation& rhs) const
+        {
+            return GeographicLocation(_v[0]+rhs._v[0], _v[1]+rhs._v[1]);
+        }
+
+        /// binary vector subtract
+        inline const GeographicLocation operator-( const GeographicLocation& rhs) const
+        {
+            return GeographicLocation(_v[0]-rhs._v[0], _v[1]-rhs._v[1]);
+        }
+
+        friend inline std::ostream& operator << (std::ostream& output, const GeographicLocation& loc)
+        {
+            output << loc._v[0] << " " << loc._v[1];
+            return output;  // to enable cascading
+        }
+
+    private:
+        // Note the convention is to store lat in _v[0] and lon in _v[1].
+        // This is contrary to typical X-Y convention. Who decided lat should come
+        //   before lon anyway? I'd like a word with him...
+        double _v[2];
+
+};  // end of class GeographicLocation
+
+}   // end of namespace osgSim
+
+#endif

src/osgPlugins/flt/FltFile.cpp

@@ -13,6 +13,8 @@
 #include <osgDB/FileUtils>
 #include <osgDB/FileNameUtils>
 
+#include <osgSim/GeographicLocation>
+
 #include <string>
 
 
@@ -89,7 +91,21 @@ osg::Node* FltFile::readNode(const std::string& fileName)
     if (readModel(fileName))
     {
         // Convert record tree to osg scene graph
-        return convert();
+        osg::Node* model = convert();
+        
+        if (model)
+        {
+            // Store model origin in returned Node userData.
+            osg::ref_ptr<osgSim::GeographicLocation> loc = new osgSim::GeographicLocation;
+            double lat, lon;
+            getOrigin( lat, lon );
+            loc->set( lat, lon );
+            model->setUserData( loc.get() );
+            
+            osg::notify(osg::INFO)<<"FltFile::readNode("<<fileName<<") lat="<<lat<<" lon="<<lon<<std::endl;
+        
+            return model;
+        }
     }
 
     return NULL;
@@ -254,6 +270,20 @@ int FltFile::getFlightVersion() const
 }
 
 
+void FltFile::getOrigin( double& latitude, double& longitude ) const
+{
+    if (_headerRecord.get())
+    {
+        SHeader* pSHeader = (SHeader*)_headerRecord.get()->getData();
+        if (pSHeader)
+        {
+            latitude = pSHeader->Origin.x();
+            longitude = pSHeader->Origin.y();
+        }
+    }
+}
+
+
 std::string FltFile::getDesiredUnitsString() const
 {
     switch (_desiredUnits)

src/osgPlugins/flt/FltFile.h

@@ -64,6 +64,7 @@ class FltFile : public osg::Referenced
 
         int getFlightVersion() const;
         inline HeaderRecord* getHeaderRecord() { return _headerRecord.get(); }
+        void getOrigin( double& latitude, double& longitude ) const;
 
     protected: