Hi Norman, > In the paper this appears to be based on a 'flat Earth' model > i.e. lon lat are taken to be simple X, Y or Cos(medianX)*X,Y > > Perhaps I am missing something or you have extended the engine > since this was written ?
I don't remember if this was mentioned in the paper, but we use vertex shaders to simulate earth curvature (but could also be done on the CPU). The underlying datasets are projected; for whole earth visualisation, we split the earth into UTM zones (transverse mercator projection). This is important in order to limit map distortions and to retain valid error bounds for our elevation and texture data. I would have to look at the projection you mentioned, but I don't think it would be very well suited for our engine; because of its global nature there will inevitably be areas of high distortion. Additionally, the fact that a single landsat-textured UTM zone is a few 100 MB in size makes a monolithic global dataset unpractical. > Are you folks familiar with this work > http://globe.sintef.no/documentation/projection.html bye, Manuel _______________________________________________ Flightgear-devel mailing list Flightgear-devel@flightgear.org http://mail.flightgear.org/mailman/listinfo/flightgear-devel 2f585eeea02e2c79d7b1d8c4963bae2d
