Hi Maciej, This isn't a bug, rather just an attribute of the way that the resolution selection algorithm is working for each tile, if a tie contains a high res region of elevation data then it'll be sampled at a high res, if it doesn't then a lower res of tile will be used. At the lowest level of detail the tile covers the whole earth so contains the high res insert so gets sampled highly, as you zoom in to high res tiles only the tiles which still contain the high res region have their res kept high.
In wireframe this does look a bit odd, but that really isn't a desgin constraint for rendering, it's how it looks when a mesh that is key, if you see visual artifacts then it's being undersampled, but if you don't the choice of lower res is the most efficient thing to do. In the case of whole earth databases I don't the sampling is currently not kept high enough in areas without any elevation data as the curvature of the earth is a bit too tight to get away with the res shown so when wrapping up VPB 1.0 it's my plan to add in a some code that sets the lowest res chosen based on the how curved a tile is. This is will exhibit the seemingly "odd" behavior in wireframe mode, but will avoid the outline of the earth looking tessellated. Robert. On Sat, Dec 13, 2008 at 11:37 PM, Maciej Krol <mack...@gmail.com> wrote: > Hi all, > > I am playing around with earth database from > http://www.openscenegraph.org/data/earth_bayarea/earth.ive (Thanks Robert). > There are two problems with LOD switching which can be easily seen in > wireframe mode (w key) of osgviewer. > > First of all when the earth is being zoomed out from starting location > (attached wire_0.jpg) earth tessellation increases (wire_1A.jpg). This is > rather strange, since distance between camera and center of PagedLOD is > obviously increasing. > > Second, when I start to zoom in, LOD of eastern hemisphere decreases > (wire_1B.jpg). Zooming further reveals strange LOD switching pattern > (example switch from wire_2A.jpg to wire_2B.jpg). When the center tile > increases its LOD, neighbour tiles decrease their LOD. Maybe this is related > with PagedLOD centers of new tiles? I am beginner with the VPB and > geocentric databases. Is this a proper behaviour? > > I am using OSG 2.7.6 on WinXP VS2005 SP1. > > Regards, > Maciej > _______________________________________________ > osg-users mailing list > osg-users@lists.openscenegraph.org > http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org > > _______________________________________________ osg-users mailing list osg-users@lists.openscenegraph.org http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org
