Irradiance Map (vrmap) optimizing

[jujubee]

When saving to vrmap for stills, what tweaks can you perform to the Irradiance map to speed up quality and render times? Let's say we are using IR/LC for primary and secondary bounces on a final image. Final resolution will be 1200x1200.

Reduction:

1) Turn off reflections under Global.
2) Turn AA to fixed rate and set to area?
3) Reduce output size to 1/2-3/4 final output size.
4) Reduce QMC Multiplier to 1-4?

Addition:

1) Increase min/max rate to acceptable level. (-3/-1?)
2) Increase HSph. subdivs to higher rate. (50 or is this overkill?)
3) Increase LC samples to 800+.

I'm probably off as I don't use saved IRmaps with regularity. Any other general tips/suggestions???

[priad]

AA and reflexion are computed after so they optimize nothing in the irradiance map calcul when you only compute it.

[jujubee]

So you're saying that it doesn't matter if they are turned on or off if all you're trying to achieve is a faster saved IRmap output?

[priad]

Sorry I have make a mistake I'm testing it now.

first one With reflexion second without




First without area AA filter second with it.



image sample fixed rate subd 1


image sample fixed rate subd 6

[jujubee]

I think I made a mistake for step 1 under reduction. You definitely don't want to turn off Reflections when creating a IRmap as the bounces also add to the file (assuming you have lots of reflections and glossies that are noticecable/used within your scene.

[priad]

But there is something here that I can't understand:
Why AA filter or AA change something, this the last computing thing in an image, no?
And why we can change reflexion after have saving irmep without artifact?

[jujubee]

Thanks Priad for the update. : In retrospect, I should've added this post to the general section instead of off-topic.

I read through some posts about being able to disable secondary (lightcache) when IR/LC is initially used to save out an IRmap. The Lightcache information is supposedly saved out with the Irmap. However, whenever I render from a saved IRmap with lightcache disabled, my new renders are missing the glossy reflections (whether it's turned on or turned off in the general) and the image is generally darker. I'm thinking that the Lightcache is not being carried through the saved IRmap file.

I haven't bothered to save out the lightcache separately - I thought this information would be passed on to the Irmap automatically. It's set for 'on Render End Don't delete.' I'm going to try to save both separately and see if that makes a difference.

[RErender]

I've noticed that when using a saved imap it works to set the lightcache at a very low setting (not sure how low) of 24 or so to enable the glossie reflections, the fake ones at least. I've been meaning to test this further but haven't gotten to it yet. Maybe if you guys are in a testing mood...

[jujubee]

Priad - wish I coudl answer those questions - they make me confused.

Well, I rendered out the scene and saved the two maps out separately. Loaded both 'from file' and same results - a darker render.

it works to set the lightcache at a very low setting... the fake ones at least.

Fake ones? I often use glossy with a fresnel map in a white reflect box. Not sure if that's what you are referring to.

The only other thing I could think of that may be causing the missing glossies reflections from the saved IRmap is my use of a vraylight inside the scene. The 'light' is contained in a 'frosted glass' tube with an 'output' map set to 1.5 in the diffuse. Now that I think about it - this may be the source of my darkening issue - perhaps Vray isn't calculating the multiplying effect of an 'output' map used in such a way to redistributie light samples within the scene - it would almost have to act as a light. The final effects render out in the scene but doesn't save to the Irmap (or lightcache.) Anyhow - this particular issue may be heading away from the topic of optimization and more of a general bug report.

[priad]

http://www.chaoticdimension.com/foru...ic.php?t=11553
in this thread Vlado says that we can totaly unchecked secondary bounce when you have glossy with use lightcache for glossy.

And I have make a very strange test:

Light cache set to 1 with a saved irmap (not a saved lightcache)


Light cache set to 24 with a saved irmap (not a saved lightcache)


Light cache set to 2400 with a saved irmap (not a saved lightcache)


Have you see that! Lightcache set to 24 is faster than 1
There is something here that i can't understand.

[jujubee]

1, 24... are these the prepasses you are adjusting?

[priad]

they are the subdiv

[Morbid Angel]

ofcourse reflection/refraction affects the irradience. it must, because the brightness of bounced gi depends on the brightness of the reflected surface.
I must say that lightmap is a great addition to gi. While it provides infinite bounce, it also renders fast and works with animation well.

[jujubee]

I don't think IRmaps save gradient ramp information with the outputs multiplied.

Here's a basic scene. There's a plain Vray light on top surrounded by a tube. This tube has an output map to boost the light inside. The bottom light is a VraylightMtl with a Gradient Ramp in the Texmap - surrounded by another output map tube :



...the same scene loaded with the IRmap and Lighcache disabled:



Here's the basic scene with the outside tubes removed:



...scene rendered from an irradiance map loaded with the tubes removed:



In case anyone wants to try for themselves...:
download scene here.

[s0real]

Re: Irradiance Map (vrmap) optimizing

3) Reduce output size to 1/2-3/4 final output size.

isn't that what the min/max rate is for in the irmap rollout?
i was under the impression that by reducing these both by 1 would be equal to halving the output size...