Light Cache and RAM

[frodopytlicek]

Hi so far I know Light Cache require loading all textures into RAM before actual rendering, so they canot be loaded/unloaded on demand to save RAM. Im right? We stopped using Light Cache because of this for texture heavy scenes but with the new path guidance technology Im tempted to use it again (until it will be awayable for brute force) My question is, is there some way how to same RAM with Light Cache?
Thanks

[^Lele^]

It will not load *all* the textures, but surely a lot of those pertaining to a given view, as it is progressive, full-frame, 100-bounces tracing.
This said, it doesn't mean they cannot be unloaded *after* the LC is done, if the bucket renderer decides they need to be unloaded (i.e. the memory limit has been exceeded.).
Mileage will vary per frame (based on what the camera sees, with what lighting), but testing should be fairly easy to perform.

[frodopytlicek]

Yes they wil unload after light cache is done but if the scene is realy texture heavy it can eat up my RAM before calculation of LC is done.

[^Lele^]

Indeed.
That's the mileage that varies by the shot.
If you know you're already marginal with memory, then avoid both the LC and the PG addition: they will both require more ram than a bucketed BF render would.
However, you may find more RAM in other places, like the VFB.

[frodopytlicek]

Maybe downsamplig of textures for light cache calculationt would be good. Something like Vray GPU have.

[^Lele^]

Use .TX files, and you'll already be optimal for a given rendered view.
I don't see any downsampling done by GPU for the LC, btw: the log is clear pre-loading maps at their mip 0 (i.e. higher res available).