Iray speed setting - in case your renders are waaaaaay too slow!

hphoenix

AndyS said:

Sorry Richard,

Richard Haseltine said:

What do you want? Iray can - given enough time/samples and a realistically filled environment - produce an accurate(ish) representation of a badly lit photo if that is your goal.

you still didn't get it.

If you claim to render photorealistic, you have to compare it with the real situation in open nature or your sun-lit livingroom.
On photographs the contrast of light and shadow is very strong. Way too strong for our brain. So our little computer in our head compensates it. Say: if the area lighted by the sun is photographed with 100ASA, our brain compensates the shadow as if it was photographed at the same time with 1000ASA.

But if you do that in your renders by applying additional light sources without any real physical device, you're no longer photorealistic. As a workaround you may compensate it with gamma-correction.

As I already told you:
If you're in your photostudio or any fantasy scene, you can add additional lights as much and what kind ever as you want.
But for real scenes there're only the native lights allowed to stay photorealistic.

That's the scale to compare with !
For most of the situations that means to be patient enough to render over 99.x% of convergement. And try to avoid too much shadowed areas? The good balance of light and shadow is that special of best pictures.

Oh, we have engines that can do that.  They're called Photonic interaction simulations.  Given a typical DAZ scene, it shouldn't take today's computers more than a few decades to produce a TRULY photorealistic image......

PBR or 'photorealistic' is a term that gets bandied about a lot, but doesn't have a precise and non-ambiguous definition.  While "Phyiscally-Based" and "PhotoReal" have clear meanings, the fact remains that for creating images via the computers of today, certain things HAVE to be approximated.  Simplified.  Accelerated.  And that all comes with a cost to the 'realism' in the resulting images.

The contrast on photographs is usually enhanced during development and processing.  Just taking the image with certain focus, f/Stop, film, and shutter speed is the beginning.  Then the image is developed.  During this process, dodging and burning are done, the durations in developer and fixer are tweaked, and a lot more.  Even automated 'Fotomat' processing does this to some extent (thanks to computers.)

Unlike the human eye and the human brain, which work together to do all of that hundreds of times a second, and doing even more, filling in missing information and more.

Complaining that a 'PBR' or 'Photorealistic' renderer isn't 'realistic' enough is like complaining that cars can't fly yet.  If you need more than what we have now, build it yourself.  Good luck.  Photon mapping and beam-tracing algorithms took years to figure out (try reading the original academic papers on them) and even longer to optimize....and then hardware had to get fast enough and memory dense enough for it to be done on the desktop with reasonable speed.

What is PhotoRealism?  Doing the best we have with what exists now, and taking what shortcuts we need to in order to make it even closer.  If you don't like/want to take shortcuts, or have ethical issues with them, find another renderer.  You'll find they ALL do it, to various extents, for the reasons above......

 

 

mikael-aronsson

As always in graphics the point is to make it look real (if that is your goal), no one cares if the renderer do it the correct way, the only thing that counts is the end result image, "photorealistic" has been used for at least 35 years since the first crappy ray tracers rendered glass balls over checkerboard floors.

If you want to render "photorealistic" you need to wait, each primary ray will split up in a huge amount of rays for different wavelength of light everytime it hit somethings, just render one ray in a photorealistic way will take ages, there is no such thing as a photo realistic or unbiased renderer in existence, and no, path tracing, photon mapping, radiosity, metropolis, ambient occlusion does not make it photorealistic, they all do an approximation that is not even close to "photorealistic".

So why not just enjoy the cool pictures that can be created with modern renderer instead.

 

Oso3D

Why is that important?

In real life we do all sorts of tricks to manipulate light to produce an effect. If the effect looks right, why does it matter?

Look at how many night-time scenes in movies that are actually shot during the day and adjusted.

 

bluejaunte

AndyS said:

Sorry Richard,

Richard Haseltine said:

What do you want? Iray can - given enough time/samples and a realistically filled environment - produce an accurate(ish) representation of a badly lit photo if that is your goal.

you still didn't get it.

If you claim to render photorealistic, you have to compare it with the real situation in open nature or your sun-lit livingroom.
On photographs the contrast of light and shadow is very strong. Way too strong for our brain. So our little computer in our head compensates it. Say: if the area lighted by the sun is photographed with 100ASA, our brain compensates the shadow as if it was photographed at the same time with 1000ASA.

But if you do that in your renders by applying additional light sources without any real physical device, you're no longer photorealistic. As a workaround you may compensate it with gamma-correction.

As I already told you:
If you're in your photostudio or any fantasy scene, you can add additional lights as much and what kind ever as you want.
But for real scenes there're only the native lights allowed to stay photorealistic.

That's the scale to compare with !
For most of the situations that means to be patient enough to render over 99.x% of convergement. And try to avoid too much shadowed areas? The good balance of light and shadow is that special of best pictures.

Never heard the term "photorealistic" in CG described as "natural light only", especially since there is no natural light in any renderer to begin with. It's simply used to describe how realistic a render looks and how indistinguishable it is from real life. Wether the scene was lit like a fashion or a movie or an outdoor shoot using available light only is irrelevant. Surely any scene in a movie, no matter how artificially lit, qualifies as photorealistic since we see real objects and real surfaces and real light. The light source isn't relevant, light is light wether it comes from the sun or a desk lamp or studio gear.

Tobor

The masters, painting 200 to 400 years ago, created "photorealistic" scenes using plausible light sources. Obviously they were not photo-anything, as that science had not yet been invented. They didn't always paint what they saw, but what they wanted to depict.

Their skills and talent are why their work is considered treasures today, and sell for millions of dollars. No one needs to follow someone else's ideas of the "rules" to create fine art.  You don't become a Vermeer or a Caravaggio doing that.

evilded777

Richard Haseltine said:

AndyS said:

Hi Richard,

Richard Haseltine said:

AndyS said:

Mattymanx said:

Iray likes more light.  More light makes it render faster

so far a nice hint. But simply increasing the intensity of the lightsources in your scene (and adapting the tone mapping settings of cause) doesn't help, cause what slows down render times is the amount of indirectly lighted areas (shadows).
Adding some additional lights to give more light into the shadow areas is NOT photoreal and not a valid solution for serious scenes.
For fantasy scenes you may do what ever you want.

It's what photographers do, with reflectors and softboxes. If you look at photos of a photoshoot there are often as many lighting stands as on a film set.

that's right.
But I'm talking about real scenes. For outdoor scenes there is the sun the only light source. For indoor the lamps of the set (built in by the creator) are the only available light sources.
That moment you add further light sources without any physically corresponding object, it isn't a real setup anymore. It is a fantasy scene or a photostudio setup.
And as I previously stated: In that case you can do what ever you want - but it is NOT photorealistic - the quality claimed by nVidia.

What do you want? Iray can - given enough time/samples and a realistically filled environment - produce an accurate(ish) representation of a badly lit photo if that is your goal. It can also produce a photorealistic(ish) image of a scene lit by modelled reflectors and soft-boxes. Or you can cheat by having emissive surfaces. None of this conflicts with the claim of photorealism (though that is no doubt a marketing term, not a precise description of the engine's capabilities).

Richard wins. But then, doesn't he always?

evilded777

Tobor said:

The masters, painting 200 to 400 years ago, created "photorealistic" scenes using plausible light sources. Obviously they were not photo-anything, as that science had not yet been invented. They didn't always paint what they saw, but what they wanted to depict.

Their skills and talent are why their work is considered treasures today, and sell for millions of dollars. No one needs to follow someone else's ideas of the "rules" to create fine art.  You don't become a Vermeer or a Caravaggio doing that.

Extra credit. You guys make me happy inside.

Kevin Sanderson

1. detailed and unidealized representation in art, especially of banal, mundane, or sordid aspects of life.

2. detailed visual representation, like that obtained in a photograph, in a non-photographic medium such as animation or computer graphics.

AndyS, you're talking realistic, unidealized - as the first part of the definition. Richard, nVidia and most others in CG are talking the second part.

janemzen

Hi.

Does Iray Ghost Light Kit help speed up the render time even if you, as I do, work on a Mac?

janemzen

(see above) sorry, forgot to give my specs. iMac Retina 5k 2014. Processor 4 GHz intel Core17 Grafik AMD Radeon R9 M290X 2048 MB

Hope that is enough information to give my a clue if Iray Ghost Light Kit 2 will help speed up my renders. And if so; how much, aprox.

Thanks.  

tooning32_d7aab4aa88

Yes Ghost light 1 speed up very much any of my render!! Very good product but i havent try the 2

AndyS

I never used the Ghostlight product.

I invented it by myself long time before. Even created such kind of artificial lights for the "old" 3Delight renders to amplify the diffuse daylight entering through the windows of a set using UALs.

nonesuch00

I use ghostlights only in scenes where I know that there is enough light to use like 400 or 800 ISO film with a real camera but for whatever reason in DS with Sun & Sky the scene is pitch black, eg, render inside the DAZ Barn with Sun & Sky set to 8:00 AM on Jun 22 at Salt Lake City without Ghostlights and it is nearly black inside the barn even though there are either 3 or 4 windows running along the long sides of the barn.

Mattymanx

AndyS said:

Mattymanx said:

Iray likes more light.  More light makes it render faster

so far a nice hint. But simply increasing the intensity of the lightsources in your scene (and adapting the tone mapping settings of cause) doesn't help, cause what slows down render times is the amount of indirectly lighted areas (shadows).
Adding some additional lights to give more light into the shadow areas is NOT photoreal and not a valid solution for serious scenes.
For fantasy scenes you may do what ever you want.

My appoligies for not being clear.

 

I was not refering to increasing input of the light but infact adding more lights. 

Also, if you are just using mesh lights to light a scene, using the Sun/Sky setting will help it render a bit faster.

Daikatana

timmins.william said:

Why is that important?

In real life we do all sorts of tricks to manipulate light to produce an effect. If the effect looks right, why does it matter?

Look at how many night-time scenes in movies that are actually shot during the day and adjusted.

 

This

AndyS

Hi,

Mattymanx said:

My appoligies for not being clear.

I was not refering to increasing input of the light but infact adding more lights. 

OK, misunderstanding.

Mattymanx said:

Also, if you are just using mesh lights to light a scene, using the Sun/Sky setting will help it render a bit faster.

Hm funny. Where do you use meshlights? Mostly for the ceiling lamps or other lamps in a closed room - indoor scene. For most kind of interior scenes, Sun-Sky is useless.
And outdoors with direct sunlight there is a lot of shadow. Shadowed areas need over 99% of convergement to let the grainyness disappear. Lighting up those shadows with further lightsources destoies photoreality.

Except you do it for cinema (or TV). Here the natural contrast is way too big for the photographic material or TV screen.
That explaines why night time sceens are shot during day using dark blue filters. But for real photographers noticing that technique is really bothering.

hocku100

photoREAL is nonsens

1   human eye = real

2   photo film is close to real, but not real

3   your display (0-255 RGB) absolutly not real, can"t give real lightness and contrast

4   forget that and set light sources as you wish

 

inquire

scott_5a61529b50 said:

Okay, I just so happened to stumble upon a comment mentioned in another thread .. gave it a try .. and it's like WOW! .. NOW things work! SO I'm repeating this for the benefit of people like myself who are wondering just what the hell is up with Iray and why it won't play nice!

So here it is:

In the Render Setting - Optimization tab menu .. change from 'memory' to 'speed'. Hit render .. and watch your machine rock!

I have a very VERY expensive 2014 model Mac Pro, with 6 cores of E5 loveliness, 32 gig of ECC ram .. and twin AMD Fire Pro D500 graphics cards both with 3 Gig of Ram on them ... so when I tell you my iRay renders were crawling and eventually grinding to a halt for no reason, you'll understand why I'm fucking pissed! No render engine on the planet would be bringing my beast to it's knees.

So after trying the 'speed' setting I'm happy to say that my computer has regained its dignity and is rendering kick ass iRay scenes .. much MUCH faster. The problem last time was that I got to hour 50 of rendering and found nothing happening at all. The program wasn't locked up .. but it sure wasn't getting anywhere.

I suppose the 'Memory' setting is for use with the NVIDIA graphics cards?? All very well if you have one but if not you're kinda screwed. Well that is unless yo change it to speed and all of a sudden it works. Speed - really should be the default option here. It should be obvious .. but, if you're like me, you thought it best to leave all the settings at default .. lest it blow something up!

Thank you very much for this comment. I have a Mac Pro, late 2013. I'm going to try this out.

nonesuch00

Me too, memory is really only for folk that have 12GB or less computer RAM. I had to use memory often before I upgraded to 16GB RAM.