Stephane, When we deploy txp databases, we always create an "archive.prj" file to accompany the "archive.txp" file. The prj file contains a WKT-format description of the projection. (WKT is a standard format that OGR can read directly.) This, along with the offsets in "projInfo.txt", gives you everything you need for spatial referencing.
As for the LA database, best guess would be either UTM 11N or California State Plane Zone V. But that is just a guess. The real answer is to check the source TerraVista project if you can. -gw -- Glenn Waldron : Pelican Mapping : http://pelicanmapping.com : 703-652-4791 On Dec 4, 2007 3:10 AM, Stephane DUGUET <[EMAIL PROTECTED]> wrote: > Thanks Glenn, > > > > My txp file is « Los Angeles ». > > I'll have a look to OGR/GDAL and come back to you is any issue. > > > > By the way, the most important for my project is to know the projection > type associated with the terrain is mandatory. So If I want to be compatible > with any terrain, I need to introduce a kind of terrain's user description > at selection time. > > > > BR, > > > > Stephane > > > ------------------------------ > > *De :* [EMAIL PROTECTED] [mailto: > [EMAIL PROTECTED] *De la part de* Glenn Waldron > *Envoyé :* lundi 3 décembre 2007 19:10 > > *À :* OpenSceneGraph Users > *Objet :* Re: [osg-users] convert GPS coordinates to local terrain > coordinates > > > > Stephane, > > The TXP doesn't explicitly contain its projection. You need to go back to > the TerraVista project. We can make an educated guess though; Where is your > database? City, country? > > As for converting the lat/lon, OSG does not do this natively. You can use > OGR ( http://gdal.org/ogr/) which is part of GDAL. Or (shameless plug) use > the osgGIS library (http://osggis.org) which has a SpatialReference class > that encapsulates OGR/PROJ4 coordinate conversion. > > -gw > > On Dec 3, 2007 11:08 AM, Stephane DUGUET <[EMAIL PROTECTED]> wrote: > > Thanks Glenn, > > > > It helped a lot as I was completely wrong. > > > > My projInfo.txt file is as following, meaning my offsets are set to 0? > > > > My csm=Projected > > originlat=33.094356133212699 > > originlon=-117.642398847633000 > > zunits=1.000000000000000 > > selectorId=60000 > > dcType=NONE > > dcSelectorId=0 > > txpOffsetX=0.000000 > > txpOffsetY=0.000000 > > txpOffsetZ=0.000000 > > > > By the way how can I retrieve the terrain projection type? > > And then, how can I convert lat/lon to the terrain's projection? > > > > BR, > > > Stephane > > > ------------------------------ > > *De :* [EMAIL PROTECTED] [mailto: > [EMAIL PROTECTED] *De la part de* Glenn Waldron > *Envoyé :* lundi 3 décembre 2007 16:47 > *À :* OpenSceneGraph Users > *Objet :* Re: [osg-users] convert GPS coordinates to local terrain > coordinates > > > > Stephane, > > If you TXP database is in a flat-earth projection, like UTM or state > plane, the osg::Ellipsoid functions will not help. They convert to and from > geocentric (earth-centered) coordinates. > > TerraVista generates a " projInfo.txt" file along with the TXP database. > This contains the "txpOffsetX" and "txpOffsetY" properties that tell the > local offset of the lower-left corner of your TXP terrain, relative to the > geographic projection in which you generated the terrain. > > So to go from lat/lon to scene coordinates, you need to: > > 1. convert lat/lon to the terrain's projection (e.g., UTM) > 2. translate the resulting coordinates by the offset in the projInfo.txtfile > > hth -gw > > On Dec 3, 2007 9:59 AM, Stephane DUGUET <[EMAIL PROTECTED]> wrote: > > 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 > > > > > > > > > _______________________________________________ > osg-users mailing list > osg-users@lists.openscenegraph.org > http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org > > > > > -- > Glenn Waldron : Pelican Mapping : http://pelicanmapping.com : 703-652-4791 > > > > _______________________________________________ > osg-users mailing list > osg-users@lists.openscenegraph.org > http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org > > > > > -- > Glenn Waldron : Pelican Mapping : http://pelicanmapping.com : 703-652-4791 > > > _______________________________________________ > osg-users mailing list > osg-users@lists.openscenegraph.org > http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org > >
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