Re: [Flightgear-scenery] [Flightgear-devel] Scenery manager

[Adrian M. <kan...@gm...>]

On Sunday, December 16, 2012 12:35:20 Stuart Buchanan wrote:
> Hi Adrian,
> 
> On Sun, Dec 16, 2012 at 4:32 AM, Adrian Musceac wrote:
> > I am presenting an experimental (WIP) method to reduce memory consumption
> > by scenery with 30%, while increasing the visibility distance 4 times.
> > This method relies on some kind of LOD system, without mesh
> > simplification. People smarter than me can come up with a safe algorithm
> > to do that, but I'm afraid it requires changes to Terragear. Right now
> > mesh simplification was not
> 
> Could you explain how your system works?
> 
> Presumably you are making some change to the tiles for the low
> resolution version?
> 
> -Stuart

Hi Stuart,
It' basically very simple. Far tiles no longer compute anything other than 
it's own geometry, and also use a very low resolution texture set, obtained by 
running a batch resize on the regular texture set.
This allows me to have 2.5 times larger view distance in high detail (SRTM) 
terrain with same memory consumption. There is of course a slight increase in 
disk IO, but I have only tested this with multithreading enabled on a dual 
core CPU. 
Load times for far tiles are actually smaller, since no calculations other 
than geometry and effects are performed on them.
Inner tiles close to the viewer position are normal tiles, nothing changed.
That's basically it.
I need to refactor the code a bit before I can show it, I wrote it fast and 
while half asleep.

Now, the really big stuff would be load-time mesh simplification, and I have 
read a couple of papers that seem to suggest that's possibile, but would 
require some changes to the BTG format. I leave that up to the Terragear guys, 
I am not very familiar with the way their mesh construction works.

Cheers,
Adrian