Hi Alex, I've done a review of your changes and don't feel that the approach you have taken is appropriate, first up the default size quadruples the number of vertices per tile, and secondly the accounting for curvature seems based on some that roughly works for your purposes but for what I can make out isn't based on any actual error metric.
What I would have thought that would be appropriate would be to have an error metric by tested against the vertical offsets that the faceted mesh would have from the curved surface of the ellipsoid. The maximum error would be found at the mid of each triangle on the mesh, the smaller the triangles the smaller the error. You could probably simplify it so just compute the error based on separate lat/long divisions for the number of columns and rows. The error metric would be best done as a pixel error, and have the LOD range and a default screen resolution (say 1280x1024) used as the basis to compute the acceptable error in world coordinates, from this one could then compute the lat/long delta which is the largest tolerable delta, then from this compute the number of rows and columns. Robert. On Tue, Nov 16, 2010 at 5:16 PM, Alexander Irion <[email protected]> wrote: > Hi! > > I created a dataset with osgdem, where the whole earth is covered by > textures, but height values are only given for one country. > > One half of the whole earth was looking very "polygonal", while the other > half - where the height values are given - was looking round. This happened > on level 1, while level 0 was looking round on both sides. Deeper levels were > also looking good again. > > I found the reason to reside in the method > DestinationTile::optimizeResolution(), which computed the value 8 for > numColumns and numRows for tile L1_X0_Y0, while L1_X1_Y0 is generated with 32 > x 32 colums and rows. > > The method did not take the angular extends into account for computing the > numbers of colums and rows. > > Please find the attached fix. > > --Alex > > ------------------ > Read this topic online here: > http://forum.openscenegraph.org/viewtopic.php?p=33782#33782 > > > > > Attachments: > http://forum.openscenegraph.org//files/destination_909.zip > > > _______________________________________________ > osg-submissions mailing list > [email protected] > http://lists.openscenegraph.org/listinfo.cgi/osg-submissions-openscenegraph.org > _______________________________________________ osg-submissions mailing list [email protected] http://lists.openscenegraph.org/listinfo.cgi/osg-submissions-openscenegraph.org
