Hi Fern:
Sorry I haven't been able to contribute much here as of yet; this complex subject would seem to merit considerable in-depth review and first-hand testing by me prior to my venturing any troubleshooting insights that I'd intend to be meaningful.
On a practical basis, though, if I were going to add dynamic scenery to FS9, I'd consider use of FS-Enhancer (originally published by LAGO), or AES / AES-Lite by Oliver Pabst, (still published by Aerosoft) for greater control, and so that both animated objects and sounds could be achieved (with moving shadows ?).
The custom Python-derived engine from Umberto Colapicchioni of FSDreamTeam / Cloud9 may also merit consideration (although IIRC their use of shadowing with dynamic / animated objects is more limited than that by Oliver Pabst's methods ?).
IIUC, the FS2004 work done by Oliver Pabst at some German airports, Emma Field, various Georenders, and in AES products... use Maurizio Gavioli's VistaMare legacy "ViMa" or "IScn" IntelliScene Modules for scheduling, buffering etc. in conjunction with very sophisticated SCASM dynamic library coding based on FSRegen type objects derived from FS2002 GMax version 1.1.
This technology has also reportedly been ported over to FSX by Maurizio Gavioli and Oliver Pabst within the last year or so.
To see just how well this method works,
BOTH the FS2004 and FSX versions of Aerosoft's LOWI
"Approaching Innsbruck" packages have (2) trains with multiple passenger cars that pass each other in opposite directions, precisely following curves in the rail bed past animated rail crossings complete with sound and flashing lights !
The Innsbruck trains and other dynamic objects can be seen here:
http://www.youtube.com/v/OyxW46DPk2E&hl
Examination of the BGLs used in the FSX version of that package indicate that SCASM is still being used successfully to do these things in FSX as it was in FS2002 and earlier.
BTW: For future consideration in FSX, Aerosoft's "
Andras Field" package has shown how developer Andras Kozma used current GMAX / 3DSMax methods to produce complex and yet very realistic animations (with accompanying sound via other methods external to the MDL file), that run with remarkable fluidity...
without killing FSX frame rates.
The Andras Field animations can be seen here:
http://www.youtube.com/watch?v=r5pEp2XeuW4
IMHO, these developers are "movers and shakers" in the FS world, whose methods merit consideration for future FSX development.
For FS9 implementation of very simple "silent" objects with or without shadows, I like the idea of being able to generate such tracks by capturing one's path via a flight recorder such as "fltrec" or perhaps an edited "FS-Recorder" type data file, while still being able to precisely control object turns and other parameters in animated tracks via vector or 3D editors before compilation.
Perhaps the "Busy Objects" methods for FS2004 best implements this hybrid approach, and helps one become oriented to GMAX / 3DSMAX methods for creating both dynamic scenery and animated objects that may also be possible to achieve in FSX through somewhat 'comparable' technology.
Alternatively, scheduling AI Traffic ground vehicles might work as well, seems preferred by some FS developers, and does allow rendering of greater model details with rudimentary associated sounds / effects.
As a relative beginner in such endeavors, I anticipate learning more about this rather specialized technology over time, and hope to see a utility and/or a set of GMAX / 3DSMAX scripts developed that simplifies the process for doing this in FS... as it seems to be a daunting topic to address for even the more advanced FS Developers here as well !
Regards,
GaryGB