On Tuesday 23 March 2004 20:24, Curtis L. Olson wrote:
We triangulate the resulting set of points to produce the
surface we render. At the moment we produce and draw only a single
level of detail for the entire world. This was a design choice that
made a lot of sense at the time we made it, and still makes sense for
many reasons today.
Just a question:
What kind of reasons were that?
Primarily, the task of matching a tile of one arbitrary LOD up with it's 8 neighboring tiles, each with their own individual arbitrary LOD's, is a daunting combinatorial task.
It may not be obvioius at first glance but if there is even the tiniest rounding error at the join between tiles, this is instantly and *very* annoyingly visible as a crack.
There is a long list of ideas you could try to either match the tiles up exactly, or hide the cracks, each has their advantages and disadvantages. But in the end, doing everything with a single consistant LOD was a *lot* easier and we generally get very reasonable performance for normal visibilities in the range 10-20 miles.
Curt.
-- Curtis Olson Intelligent Vehicles Lab FlightGear Project Twin Cities [EMAIL PROTECTED] [EMAIL PROTECTED] Minnesota http://www.menet.umn.edu/~curt http://www.flightgear.org
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