Re: [Flightgear-devel] Data preprocessing (was: optimized generic_pylons and .osg models)

[Thomas <t.f...@bi...>]

Am Samstag 13 Oktober 2007 schrieb Melchior FRANZ:
> * Melchior FRANZ -- Saturday 13 October 2007:
> > Caching would mean [...]
>
> BTW: (real) caching would be a good idea. But I doubt
> that *.osg is a big win. It would have to be the native
> binary format *.ive to make sense, no?
>
> And there would have to be a separate cache dir in
> /var/tmp/ or /var/lib/, not in the data dir, which
> isn't usually user writable.

An alternative might be a "compiled" data dir, i.e. use automake to preprocess 
the ASCII representation to space and I/O efficient binary files. At the cost 
(inconvenience) of an extra compile step for data developers, you gain a big 
improvement in startup time and disk usage in case you're a read only user.

I can see uses for this with the airport, runways & navaid DB's. Given your 
proposal of spatial indices for these (I'm investigating D-Indices currently) 
it might be a good idea to store a binary version of the index/db for startup 
performance reasons. The airport DB currently holds about 21600 airports, 
which are all read into memory on startup. An on the fly generated spatial 
index would unnecessarily add significant extra time on startup for building 
the very same memory structure over and over again.

Thomas