Lv, convertLatLongHeightToXYZ gives you a point on the surface of the ellipsoid, but the actual polygons in the terrain model are just a tessellated approximation of that ellipsoid. So if you want the point on the triangulated surface, you have to convert to XYZ and then "clamp" down to the surface (using the local up-vector at that point).
Glenn Waldron : Pelican Mapping : http://pelicanmapping.com : +1.703.652.4791 On Sat, Dec 5, 2009 at 10:19 AM, Lv Qing <[email protected]> wrote: > Hi, > > I have build a geocentric coordinate earth model using VPB and want to put > a simple model on the suface of the earth. > > I use the convertLatLongHeightToXYZ function to convert the > BLH(Lat,Long,Height) of the simple model to XYZ of the > geocentric coordinate system.The result of X and Y seems OK,but the Z > coordinate is always a bit higher above the earth suface(about 5000 m). > > > > Code: > > // load the earth model > osg::CoordinateSystemNode* csn = new osg::CoordinateSystemNode; > csn->setEllipsoidModel(new osg::EllipsoidModel()); > osg::Node* TerrainNode= osgDB::readNodeFile("earth.osga"); > csn->addChild(TerrainNode); > > //convert the BLH(50,130,0) to XYZ,I set height 0. > osg::Vec3d m_surface; > > csn->getEllipsoidModel()->convertLatLongHeightToXYZ(osg:egreesToRadians(50.0f),osg:egreesToRadians(130.0f),0.0f,double(m_surface.x()),double(m_surface.y()),double(m_surface.z())); > > //draw a simple yellow line from center of the earth (osg::Vec3(0,0,0)) to > the surface (osg::Vec3d m_surface); > > osg::Geode *geode_line = new osg::Geode; > osg::Geometry *geom = new osg::Geometry(); > geode_line->addDrawable(geom); > csn->addChild(geode_line); > osg::Vec3Array *v = new osg::Vec3Array(); > v->push_back(osg::Vec3(0,0,0)); > v->push_back(m_center); > geom->setVertexArray(v); > osg::Vec4Array *vc = new osg::Vec4Array(); > vc->push_back(osg::Vec4(1.0f,0.5f,0.0f,1.0f)); > geom->setColorArray(vc); > geom->setColorBinding(osg::Geometry::BIND_PER_PRIMITIVE); > geom->addPrimitiveSet(new osg:rawArrays(osg:rimitiveSet:INES,0,2)); > > > > > > As the result ,the end of the yellow line is obviously higher than the > surface.Please tell me where I am wrong,THX! > Thank you! > > Cheers, > Lv > > ------------------ > Read this topic online here: > http://forum.openscenegraph.org/viewtopic.php?p=20950#20950 > > > > > Attachments: > http://forum.openscenegraph.org//files/getattachment1_418.jpg > > > _______________________________________________ > osg-users mailing list > [email protected] > http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org >
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