[osg-users] Refactoring DatabasePager NeedToRemovestringflagging technique

[Glenn Waldron]

On Mon, Nov 23, 2009 at 11:10 AM, Robert Osfield
<robert.osfield at gmail.com>wrote:

> Hi Wojtek,
>
> On Mon, Nov 23, 2009 at 2:34 PM, Wojciech Lewandowski
> <lewandowski at ai.com.pl> wrote:
> > But I would strongly defend merits of arguments in the post. You say we
> did
> > wrong, but whats you recommendation on mixing many intersections with
> > rendering ?  Its very common scenario. How  should we tackle it, if
> current
> > approach is wrong ?
>
> The right approach is a difficult one.  Getting a paged scene graph to
> work with intersections at highest resolutions and at the same time
> manage things for rendering with requires just the appropriate LOD
> child for the needs of visuals is awkward.   I know often vis-sim apps
> don't even try to mix the two, and have a separate process entirely
> for dealing intersections as for doing the visuals.  Some sims even
> run the visuals and intersection testing on entirely different
> machines.  Other sims use entirely separate databases for intersection
> testing and visuals.  Then there are others that use a height field
> for height above terrain testing...
>

Wojtek,

The "keep it separate" approach is what we use in osgEarth. The idea is to
fetch terrain tiles directly, based on your target sampling resolution,
instead of traversing the whole LOD hierarchy. Take a took at the
ElevationManager utility. Perhaps it can provide some inspiration:

http://wush.net/trac/osgearth/browser/trunk/src/osgEarthUtil/ElevationManager

Glenn
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