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

[studioDIM]

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.

let's say you have the scene already exposed for sun and sky at midday.
This is important to have some sort of common reference.
In that case, the brightest spot in the scene, out sun, is around 385.0 float, give or take some number.
Whatever the ISOs of the camera at that point, your hdri should be multiplied by 385.0/45.375, or by 8.48, to be nicely visible in THAT scene, under THAT exposure.
Which figures with what you were saying you used to make it appear correctly, if by chance

Lele

[glorybound]

.255

ok, I am back to this method. My only issue is I have hundreds of texture maps and colors. Do I actually have to edit each and everyone? Over at elite he is doing some really great stuff. He is reducing the intensity of the sun. Why again isn't that the way to go?

[jacksc02]

just use the method that you feel comfortable with, there is no golden rule. Just find a method/workflow that works for you.

[CCS]

It all depends on what you mean by the "way to go".

You could certainly lower the sun. You could adjust the bright/dark mults in color mapping. You could use a regular MAX light. You could use a MAX camera. You could use radiosity. etc.....

What is "right"? You decide. It all depends upon how you want to work.

The point of this method is taking vray to the level which it allows us to. Vlado has gone to great pains to have a *physical* sun, and *physical* camera, and has added features that react accurately to real-world conditions. After all, that's what we mean by 'physical'. We refer to a response which most closely replicates real-world measurements.

So... if we are to have a "real" sun, but we lower its intensity, it's no longer a real sun is it? The sun is the sun after all. Photographers do not reduce its power when it suits them. They deal with it by changing viewing angle, film speed, shutter speed, aperture opening, filters, etc. We do the same every day. Walk into the sunlight, and you may need to apply a filter (sunglasses). Certainly, there is an aperture adjustment (your irises). You may even have to adjust your shutter speed until your eyes grow accustomed to the situation. Walk into a dark room and everything appears black until your brain adjusts the F-stop of your eyeballs to compensate.

So, the thinking is this. If we are trying to create "photorealistic" (whatever that is) renderings, then we need to get as close to reality as possible. To many, that means using a physical sun/sky for starters. Then, to deal with the immense brightness of the sun/sky, we must have a physical camera to compensate. (From here, go back to Lele's tuts for the rationale behind the adjustmests to RGB levels.)

So, to my way of thinking, if you're considering lowering the VraySun's intensity why bother with the sun at all? It will only confuse things. Stay with whatever method you're comfortable with. But if you want a "physical" reaction, you need to follow a physical process throughout.

[Dman3d]

Ah, that makes more sense. Will give it a shot, thanks again Lele.

I have found that most people seem to think something that looks like a printed photo believe it to be more "real" than something that is real.
--update---
looks like its working, just have to find the right hdr

[studioDIM]

Re: .255

ok, I am back to this method. My only issue is I have hundreds of texture maps and colors. Do I actually have to edit each and everyone? Over at elite he is doing some really great stuff. He is reducing the intensity of the sun. Why again isn't that the way to go?

Sorry, Bobby, i missed your post before.
No, you needn't go BY HAND through all the maps and colours.
In the first post there's a link to one script i prepared that does it for you, also allowing you to change what the multiplier is (0.255 is the default, change it to suit your needs/taste), so to be able to control the contrast as well (higher multipliers lower contrast, lower multipliers, conversely, raise it).

I have to second Jacksc02, anyways: this is ONE way to go about it.
In the tut i DO try the sun de-multiplied, and discard it as it's "uncomfortable", because of the issues with spinner precision, and GI balance.
Of course, it's MY way of thinking, not THE way of thinking

Lowering the diffuse coefficient of materials, to me, simulates real life better because of the way the sunlight is scattered in the real world (while BRDF measurements are done with a close light, and little or no scattering happening) before it actually reaches an object on the earth's ground.

In the end, feel free to use or ditch this as you see fit, I won't take offense either way

Lele

[glorybound]

.255

I'll check out the script... I just finished another image using this method and again the interior designer who picks out our colors love it.

[glorybound]

converter

Why didn't I see that 3 jobs ago? Great utility! Question. If I have a bitmap and change the RGB Levels to .255, does the diffused need to be black?

[studioDIM]

nope, no need if the map amount is still set to 100 (the spinner by the map name in the map list).
Glad to hear it sorts things out for you Bobby

Lele

[voltron7]

LWF ?

Lele,

thanks for writing/making this fantastic tutorial and these great scripts.
I hate to ask this, but I must. If I were using vlado's method #3 from this thread http://www.chaosgroup.com/forum/phpB...ic.php?t=15303
than how does this affect the tutorial as far as gamma in max preferences.
I use method 3 just because I have LCD and it's clibrated with Huey. Do I still still use enable gamma in 3dmax options?
I was thinking I could just use gamma 2.2 in the vray colormapping, but is this wrong?
Sorry for these odd questions, just want to test your method out "correctly."
Flame-on

Thanks very much LeLe and to all who have contributed (positively) to this thread!
JR

[studioDIM]

Ahah, i ought to edit some of the old posts where i flame
I wasn't in a pretty shape back then...

Anyways, you're a lucky chap
Working linearly throughout is definitely the easiest of options, and the method should behave exactly as the tutorial did.
I imagine you do post work on your images, and if so, you can do any type of CC afterwards, regardless of the max / colormapping settings.
So it's up to you to choose what to do to make it look right, the method outlined only deals with how light distributes within the scene.
Ie. disregard whatever i did to colormapping in max, and just go straight into your favourite post application to do any adjustment you need.

I'm sure waiting to see samples , though, as i am curious like mad to study people which work entirely linearly

Lele

[voltron7]

Ah, Thanks LeLe! And for sparing me the flames
I did some tests yesterday and now understand what your'e saying.
I was able to acheive the same results with and without changing the max gamma options. I do some post work but in the end, I will keep the max gamma setup like the tutorials as it seems to "remove" a step in post.
This method I am finding is better beause now other lights don't need such high multipliers like before to come within reach of the vraysun.
I want to post a test image soon, just a WIP.

Thanks again
JR

[glorybound]

.255

Whenever I run your script I get this error.

i.texmap_reflection.color = i.reflection

I have tried it on three scenes so far and each scene returned the same error. I am running MAX 9 on x64

[studioDIM]

could you send me a scene @ emanuele dot lecchi at gmail dot com, please?
I cannot seem to replicate the issue here.

Thanks,
Lele

[voltron7]

Sorry about not posting test yet, the project I'm trying this has been on hold.
I'm going to still mess around with it. Hope to post soon