Hi Chris, On Wed, Jul 15, 2009 at 9:29 PM, Chris 'Xenon' Hanson<[email protected]> wrote: > Notice "CoordinateSystemType GEOCENTRIC". In my GIS-mindset, geocentric > means something > like ECEF coordinates http://en.wikipedia.org/wiki/ECEF and anything using > latitude and > longitude is GeoGRAPHIC coordinates. > > The HeightFieldLayer contains an origin and interval which can be combined > to determine > the coordinates of any vertex in the heightfield. For example, mine are > Origin 26.2000007629395 30.5 0 > XInterval 0.00079994200496003 > YInterval 0.000800018315203488 > > To me, those are GeoGRAPHIC, not GeoCENTRIC. But it may be a distinction of > terminology.
The case when the locator says GEOCENTRIC means that the data should be projected from GEOGRAPHIC into ECEF coordinates. The above Origin and XInterval, YInterval are effectively in GEOCRAPHIC in your above example, but once they've been processed by the locator the final XYZ coords with be in ECEF. If the Locator was set to GEOGRAPHIC then this projection into ECEF would not happen. So... I believe osgTerrain::Locator is actually doing what you are expecting it do and then meaning is appropriate. Your confusion probably comes from the fact above values are effectively intermediate coords in this context - as the OSG has to place in coords into lat, long, height before it can convert to ECEF xyz. > Now, in my own personal case, this is exactly what I need -- they already > appear to be > WGS84 lat/lon and I can go about my business without converting them. But I > believe in > some cases, they will need conversion so I want to make sure I can handle > that case before > I contribute this code. VPB by default uses WGS84 so will be what you want most of the time. If the model is geocentric then VPB will use WGS84. However, users can set the destination coordinate system in VPB and in this case you'll need to convert from the coordinate system it's in to WGS84 using a tool like PROJ. Robert. _______________________________________________ osg-users mailing list [email protected] http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org
