Irradiance Map (vrmap) optimizing

[flipside]

Re: Irradiance Map (vrmap) optimizing

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???

Are you simply trying to speed up the render while it's calculating the vrmap to use afterwards?

Why not just using the 'don't render final image' in the global swatches rollout? This way, vray computes the vrmap, saves it and doesn't start the rendering.

About reducing the output size, that is indeed exactly what the min max rate in IR map is for. The IR map for a render at 1600*1200 with min/max set to -4/-1 is exactly the same as 800*600 with -3/0

Usually everything you do that speeds up calculations, will degrade quality.

AA settings have no effect on the IR map calculation time.

Priad I think you understood vlado wrong. If you use the 'use licghtcache for glossy' option, you need to enable LC for second bounce. This 'use LC for glossy' info is not stored within the IR map. Vlado simply says that you better let LC for second bounce always on to avoid confusion (the only disadvantage to this is that the loaded LC map uses a bit of ram, it doesn't take longer to render if you leave it on).

[flipside]

Here's a small test:

I first rendered the image with IR map and LC, use LC for glossies was ON. Then saved both the IR map and the LC map. Then I set both IR map and LC to load their maps from the previously saved files.

This is the original image I rendered (so rendertime includes IR map and LC calculation time)





This image is rendered with LC for second bounce still active:




This one I disabled secondary bounce engine and rendered




This clearly shows that when you want to use the 'use LC for glossy' option, you need to leave secondary GI set to LC! If you disable it, the glossies don't use the LC and are computed in the normal way. This is because the LC for glossy information is not saved in the LC map or IR map.

[flipside]

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.

Reflection and refraction only affect irradiance if you have the reflection and refraction GI caustics turned on in the GI rollout. If they are turned off, the reflection and refraction parameter are not taken into account when calculating IR map, only the diffuse component will be used.

But since refractive GI caustics are turned on by default, and the effect of this parameter is very visible when using glass for example, you better don't turn off reflect/refract in global as mistakes are easily made.

But if you don't use refract/reflect GI anyway, you can turn off reflect/refract in global during IR map calculation.

[jujubee]

Why not just using the 'don't render final image' in the global swatches rollout?

That would probably help... ALOT

About reducing the output size, that is indeed exactly what the min max rate in IR map is for. The IR map for a render at 1600*1200 with min/max set to -4/-1 is exactly the same as 800*600 with -3/0

These can be interchanged instead of size reduction. But where are you getting these min/max values from? Is there a chart somewhere which posts these values?

This clearly shows that when you want to use the 'use LC for glossy' option, you need to leave secondary GI set to LC!

Beyond render times, your images look the same!

[s0real]

These can be interchanged instead of size reduction. But where are you getting these min/max values from? Is there a chart somewhere which posts these values?

every time you double the image size you can effectively reduce both the min and max rates by 1 instead of saving out the irr map at a smaller size.

eg;
640x480 min rate -3 max rate -1 (medium setting)
1280x960 min rate -4 max rate -2 (custom)
2560x1920 min rate -5 max rate -3 (custom)

vlado did a good room tutorial using a scene from flipside that explained settings for irr map and lightcache amongst other things which is very useful as a guide - unfortunately i can't find it since the site overhaul!

it used to be here;
http://www.vrayrender.com/stuff/flip...l/flipside.htm

and the original thread;
http://new.chaosgroup.com/forum/phpB...ght=test+scene

[jujubee]

Yeah. I recall going through the 'Optimizing Flipside's scene' and it taught me alot about settings. It was very useful. My only problem with some of the tutorials is that they lead through example but doesn't always clearly explain what he is attempting to do - I end up getting lost or forgetting. Perhaps it's just me...

[s0real]

it was a very useful tutorial.
i've pm'd Vlado to see if he can tell us if it still exists...

[flipside]

here it is:
http://www.chaosgroup.com/support/pr...s_interior.htm

(the link probably doesn't work... but it's the "rendering an interior scene" tutorial in the vray docs)

About the three images being the same, they are not. Take a look at the reflections underneath the teapots in the middle and last image. The middle ones look bad because of the "use LC for glossy rays" option.

In the last they are ok, because second bounces is turned off, so the glossy rays are now not calculated with LC, but in the normal way.

That is why you can't turn off second bounces when you want to use the LC for glossy rays option.