VRay Sun, Sky and Physical Camera video tut + Bonus Script!

[chris-x//]

flavrsaver : in your settings, image sampler is set to adaptive qmc but the next rollout is the one from adaptive subd ? am I getting mad ? (I started 1.5 a few weeks ago and it's still a pain )

[flavrsaver]

Ha, good catch there. It should be displaying the Adaptive rQMC image sampler rollout. There must be a bug with the Presets loader because it's not displaying the correct rollouts. When I go into the Image Sampler dropdown and reselect "Adaptive QMC", then it displays the correct rollout.

Sorry for the confusion. Looks like you're getting the hang of 1.5 after all.

[glorybound]

HDRI

Same question here for HDRI's. I tried using an HDRI and either the background was completely white ir the scene was to dark.

[studioDIM]

The problem with HDRIs is that the contarst ratio and range vary greatly bewteen makers.
I suggest the usage of HDRshot to manahe the correct multiplication for the map.
------HDRShop* Manage* -----
For example, measure the brightest spot in your HDR, and divide 385 (sun at midday. make the relative measurements - changes for your specific cases) by the value of that spot to find out what the multiplier for the bitmap is.
Say you have an hdr with a max brightness of 20. The multiplier to have that show white (and likely contribute to GI in the expected way) in your physcam exposed render is 385/20=19.25

As for the render panel issues, they're mostly max-bound. in scripting reloading a preset cracks it up, and the render panel needs a close and reopen.

Lele

[Dman3d]

thanks for the tip lele will give it a shot

[glorybound]

HDR

How do you measure the brightest spot in your HDR?

[jacksc02]

use HDRshop

[glorybound]

hdrshop

I got that part, but I couldn't figure out how. I can get info, but it doesn't give me meaningful information.

[studioDIM]

rolling the mouse cursor over any image area will print the RGB values (in float, of course) at the bottom-right of the screen
Try that...

Lele

[rivoli]

alternatively, if you're not comfortable using hdr shop, you might load the image in max as a screen mapped background, and check the values in the vfb (or, even simpler, view it in the mfb directly).

[rmejia]

Re: VRay Sun, Sky and Physical Camera video tut + Bonus Scri

part3: Adding GI and bringing the babe home: save 250% rendertime, and get a nicer, cleaner, more balanced picture.

Thanks for the tut and the scripts !

[R_Cyph]

You're wrong! well.. sorta

Yes, ideally the method *should* work in any context.
The method, mind you, not the values themselves, however.
The 0.255 value is chosen there purely because it works in that particular context.
The "phisicality" of it is not assured in any way other than that of mimicking the perceptual brightness of an object under those strong light intensities, which i think to be a lot darker when prepared than it is when actually perceived.
When working with standard light fixtures, in a largely LDR environment, lights in the first place do not simulate the correct intensity ( i talk of a max standard light), so going about the rest of the scene without one fixed reference (in the tutorial case, sun and sky at 1.0 multiplier) means simply one can adjust however he sees fit.
In that case I'd keep going about materials in the old fashion, for the sake of simplicity, and use the vray physcam with exposure turned off, so to avoid the issue entirely.
After all, there's normally no light in a scene with a 300 odd multiplier and no decay to care for, is there?
The physcam can however be used to expose, but i think you'll find it easier to use when in a very HDR scene, rather than in LDR ones.
Exposing a scene with low dynamic range lights might result in a perceivable loss of contrast.
And most of the exposure can be obtained, for implicitly LDR scenes, with the vray VFB or a post software and HDR imagery.
In the case of a sunlit scene, that would prove hardly viable to do in post: sure the colours would be brought back in range, but not exposing the scene with a sun at 1 would simply lead to perfectly white renders, fairly hard to work with

Hope i answered,

Lele

You're wrong! well.. sorta

Just for shitz n' giggles. I tried this tutorial in a LDR scene only lit with IES lights. and it STILL works like a charm - no loss of contrast. Although as I previously thought the ISO for the phys cam gets kinda big. So for all those who wish to use a consistant lighting workflow, one could use this method in pretty much any situation. Anywho Just thought you'd like to know and thanks again for imparting such great knowledge upon all us newbs.

[KVMaster]

codec??

What codec does this have?? Guess I don't have it yet???

[DaForce]

http://www.techsmith.com/codecs/tscc/default.asp

[Dman3d]

Finding for some HDR's the mult ends up being low
for example one in particular has 45.375 as hottest spot
200/45.375=8.67606(hdr mult) but having to multiply 200*8.67606=1735.21(iso) sort of reverse I suppose
does this seem right? It appears to work.