Possible bug using pre-calculated irmap and lightcache?

[emptyvoxel]

Hello, I'm wondering if anyone else can confirm this problem I'm having.

I'm doing four fly-through animations of a commercial airplane interior, and I have my lightcache and irradiance maps calculated. In the past I simply switched the secondary bounces to "none" for the final renders, since the lightcache is saved with the irmap.
However, I noticed today that disabling secondary bounces increases the frame render time by a factor of 4!

So in other words:

Primary bounces: pre-calculated irmap
Secondary bounces: none
Frame time: 19:29

Primary bounces: pre-calculated irmap
Secondary bounces: pre-calculated lightmap
Frame time: 5:39

The frames are identical either way, as you would expect, and the ONLY thing changed is turning secondary bounces off. Has anyone else noticed this?

The solution is to just switch the secondary bounces back on, of course, but it still confuses me. I tried it out in three separate scenes with the same results.

Thanks!

[Dman3d]

I am doing something similar but curious about a couple things
what ver of VRay are you using.

How are you combining the LC and IR together, if that is what you are
saying.

thanks

[emptyvoxel]

I am doing something similar but curious about a couple things
what ver of VRay are you using.

How are you combining the LC and IR together, if that is what you are
saying.

thanks

I'm using 1.5R2, and I think that perhaps I solved my own problem by looking back over the flythrough tutorial:

We are not using glossy reflections in this scene, but if you are using them and not using the Use light cache for glossy rays option at the same time, then you can set the Secondary GI engine to None for the final animation. This is because you won't need the light cache and turning it off will save memory.

And here:

You can have the light cache saved with the irradiance map. If done so, you can actually just turn off secondary bounces which will save memory as you wont have to load the light cache. However, if you have the light cache help precompute the glossies with the Use light cache for glossy rays option, then you'll need to go ahead and load the light cache when rendering.

So, I probably have a stray glossy reflection in there that's causing problems for V-Ray. Straight up user error!

[Dman3d]

Oh, thats what I do lol so Ive been doing it all along so I can turn
off the secondary.

I guess I did not understand that calc like that it would save the LC with
the IR, ah