Problem Using Saved Lightcache

[DanielBrew]

Hi All,

I’m not sure whether this is a bug or just the way VRay works.

When we make walkthrough animations we pretty much follow the example in Vlado’s tutorial on Spot3d.com with a few changes to try to allow the process to run unattended.

We send two jobs to the farm, the first is sent to one machine only and it calculates the irradiance maps and lightcache. The second is a dependency of the first and is sent to a number of machines and it renders the frames.

When it has finished, the first job saves the IR maps and LC to the server. Then the second job starts, it runs a pre-render script which copies the IR and LC from the server to a local drive before starting to render the frames.

Now this is where the problem starts, the rendered frames look like this:


Instead of like this:


Notice how everything with a glossy reflection or refraction appears too dark.

I’m using the LC for glossies which is why I save both the IR map and LC. I know the pre-render script works because (a) I can see the files being copied in windows explorer, and (b) the IR map is clearly being used to light the scene. Everything works ok if I use Backburner to suspend the second job while the first frames are being rendered (ie. after the files have finished copying), then activate the job once all the servers have gone to idle again. It appears that VRay needs the LC to be in place before the pre-render script has had a chance to copy it to the local drive.

Can anyone think of a reason why the servers don’t see the LC file first time round?

Thanks,

Dan[/img]

[vlado]

V-Ray loads the light cache shortly after it loads the irradiance map; it does not attempt to load it before your script is executed.

I'm not sure what goes wrong in this case; one thing that may be happening is that the servers start rendering before the light cache has been completely written to the disk. To see if this is the case, you can probably try to add some small random delay in your pre-render script and see if it helps.

Best regards,
Vlado

[DanielBrew]

Thanks for the reply Vlado, there is a 30 second delay written into the script already I'll try to increase it to 5 mins see if that makes any difference.

Dan

[vlado]

Try to make it a random delay (e.g. between 1 and 2 minutes or something like that) to avoid the case where all servers try to access the same files at once.

Best regards,
Vlado

[DanielBrew]

Try to make it a random delay (e.g. between 1 and 2 minutes or something like that) to avoid the case where all servers try to access the same files at once.

Ahh, I understand why you said random now, I'll try to do some test today.

Thanks

Dan