John, osgEarth's "LOD Blending" function does this for imagery - it references two LOD textures per tile (level n and level n+1) and blends then in the shader based on camera distance.
We are (once again) considering implementing something similar for heightfield data in the next version of osgEarth. The idea is that you use the vertex shader to alter a heightfield patch on the GPU using vertex texture lookups. Supply n and n+1 heightfields and "morph" between them using the shader. But..it's complicated. If you go down the route of creating and/or tessellating terrain on the GPU, you need to consider things like intersection testing and shadowing and other things that (currently) rely on having triangles on the CPU. Glenn Waldron / @glennwaldron On Tue, Apr 24, 2012 at 7:47 AM, John Vidar Larring <[email protected]>wrote: > Hi, > > Thankfully, there's a lot of people on this list using osgTerrain, which > means that hopefully others have pondered about the same issue that we are > currently having when rendering high resolution terrain: the visual > "popping" of terrain tiles in the terrain. > > In the sample videos below, we have tweaked the lighting to make the > visual effect more obvious: > > ftp://ftp.weatherone.tv/**projects/popping/popping_dive_**sample.mp4<ftp://ftp.weatherone.tv/projects/popping/popping_dive_sample.mp4> > ftp://ftp.weatherone.tv/**projects/popping/popping_**flight_sample.mp4<ftp://ftp.weatherone.tv/projects/popping/popping_flight_sample.mp4> > > Since we normally work with large high resolution terrains, we would like > to keep the geodetic-quadtree structure of the pagedLOD database, but we're > a bit unsure about how to address the "popping" issue within this > framework. One approach could possibly be to implement some kind of > heightfield interpolation between LOD-n and its four children in LOD-n+1 > based on camera distance*LOS_scale over a fraction of max/min view distance > for the two LOD levels...(?) . > > What approach / strategy would you suggest? Anyone who have have tried and > succeeded/failed and willing to share their experience? > > A similar discussion for terrain rendering in osgEarth is discussed here: > http://forum.osgearth.org/**height-mapping-on-GPU-**td7432851.html<http://forum.osgearth.org/height-mapping-on-GPU-td7432851.html> > > Best regards, > John > > > -- > This email was Anti Virus checked by Astaro Security Gateway. > http://www.astaro.com > ______________________________**_________________ > osg-users mailing list > osg-users@lists.**openscenegraph.org <[email protected]> > http://lists.openscenegraph.**org/listinfo.cgi/osg-users-** > openscenegraph.org<http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org> >
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