On Wed, Jun 18, 2008 at 8:06 AM, Robert Osfield <[EMAIL PROTECTED]> wrote:
> On Wed, Jun 18, 2008 at 12:41 PM, Glenn Waldron <[EMAIL PROTECTED]> > wrote: > > Robert, > > > > I propose that osg::CoordinateSystemNode should have the same > > get/setCoordinateSystemType() methods that are found in > osgTerrain::Locator. > > Without them, it is not possible to differentiate between a geocentric > and a > > projected plate carre projection. > > > > If you agree, I will submit the change. Thanks. > > I have no objection, the only thing to be wary of is if the coordinate > system string and the type disagree - this would be a garbage > in/garbage out issue, if the user sets things correctly, they will > agree, if they mess up there won't be an automatic way of checking > i.e. you'd need something like PROJ to check. The real issue that I'm facing is this: when you use osgdem with WGS84 input data, but without the --geocentric flag, you get a database with a projected coordinate system (specifically Plate Carree projection). However, the CoordinateSystemNode reports a WGS84 WKT, and the osgTerrain::Locator node reports WGS84/PROJECTED (a type disagreement) -- both of which I would argue are incorrect. In this scenario, the WKT should actually be a variant of this: PROJCS["World_Plate_Carree",GEOGCS["GCS_WGS_1984",DATUM["D_WGS_1984",SPHEROID["WGS_1984",6378137,298.257223563]],PRIMEM["Greenwich",0],UNIT["Degree",0.017453292519943295]],PROJECTION["Equirectangular"],PARAMETER["False_Easting",0],PARAMETER["False_Northing",0],PARAMETER["Central_Meridian",0],UNIT["Meter",1]] Now, when you do use --geocentric, the WGS84 WKT is OK since one can assume that this implies a geocentric database (since the OSG cannot use angular coordinates :) Anyway I guess this is more of a VPB issue. I appreciate your thoughts on the matter. Glenn -- Glenn Waldron : Pelican Mapping : http://pelicanmapping.com : 703-652-4791
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