Hi Glenn,
Yes, it definitely sounds like a fairly large implementation task, but a
geomorph (as Shayne put it), seems like the most generic fix to the
popping issue.
Best regards,
John
On 04/24/2012 12:54 PM, Glenn Waldron wrote:
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
<larr...@weatherone.tv <mailto:larr...@weatherone.tv>> 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_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
Best regards,
John
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