Hi Terry,

On 1/9/07, Terry Welsh <[EMAIL PROTECTED]> wrote:
I gave this some thought after Robert suggested it a while ago.  2
problems, though.  The first is that this would require me to have all
my data except for the highest level loaded at all times, which
defeats the purpose of paging.  The second is that I don't see any way
to turn these tiles off after the high-res tiles are loaded.

The osgdem generated database all work by having the first child of
each PagedLOD as a local geometry that isn't loaded for disk.  These
database scale at runtime without any problems and without holes.

The low res tile on each PagedLOD is loaded as part of the loading of
the tile that contains that PagedLOD so its not the case that you have
to load in all the low rest tiles at once unless you have a completely
flat scene graph containing PagedLOD which are all siblings.  What you
should be aiming for is a quad tree structure, this way only the tiles
that are needed to be rendered for the view frustum are loaded in.

Also the switching between low res and higher res versions of the
tiles automatically happens with PagedLOD when the high res version is
merged, there isn't any intervention required.  The subgraphs that are
no longer visited are also unloaded automatically.

Have a look at the osgbluemarble example, perhaps this will give you a
clearer insight of how to set up a PagedLOD quad tree in the way that
Jason and I are discussing.

Robert.
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