Adding oomph to your rendering time

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Nathanomir
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Re: Adding oomph to your rendering time

Postby Nathanomir » Tue Aug 30, 2016 2:30 am

Along similar lines, at what s/P do you recommend increasing the ISO to overexposure?
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Gederix
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Re: Adding oomph to your rendering time

Postby Gederix » Tue Aug 30, 2016 9:53 am

I tried turning dzfire torches into emitters and it broke my scene, just flooded with super-grainy noise that was not clearing up over time, and I wasnt about to wait days to see otherwise. Remove them and grain disappears. I find this happens when turning complex geometry into emitters, smooth surface work fine but with flame props I tend to get serious render noise that floods the scene and also seems to hobble the sampling speed.
I have been playing with the power light strategy and I do see a slight improvement but rereading this thread Im thinking part of the reason Im not seeing more might be due to the number of lights in the scene Im currently playing with (5 meshes and 3 emitter surfaces).
What is the purpose of the 6400 ISO? To flood the camera with light in a low light scene? Then I am guessing you reduce the iso when you get where you want to be? What does the scene look like when rendering at 6400, is it blown out, way overexposed, almost white? Id like to try it because I do low light scenes all the time (in the sense that I use snoots to create spotlights to focus meshlights and leave the periphery in shadow) but not sure what Im looking for.
Thanks!

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fuzzy70
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Re: Adding oomph to your rendering time

Postby fuzzy70 » Tue Aug 30, 2016 10:59 am

This is how I think LuxRender works, although I could be way off, but from a programmers point of view it makes sense (and i'm not prepared to trawl through thousands of lines of code to find out lol).

Whatever you have in your .lxs scene file is what Lux uses to base the render on, by that I mean light gains etc.

So imagine a simple scene with a floor, a sphere & 2 mesh lights (one to the left & one to the right pointing to the centre of the sphere), the left light has a gain of 1.0 & the right has a gain of 0.5. Lux reads your scene & uses those settings & renders the image but stores the info based on that. If you change anything in Lux while running, say make the right light gain 0.7, Lux still uses the same info it's stored but when it displays the image (tonemapping) it does some maths based on the new settings purely for what you see on the screen, the internal info remains unchanged. So in essence if your initial settings are not optimal for the scene then chances are more work/longer render may be required for it to clean up.

BTW film responses/bloom etc do not count as they are simply post effects applied by Lux at display time. Also I cannot say for certain if camera ISO/Shutter etc are used for the actual render internally or they are post effects also.

Of course if the internal data is actually modified by changing settings in Lux then essentially you risk the chance of introducing noise by altering settings if they are not subtle.

So in my mind make sure all your settings are correct in Reality like gains/camera settings etc before your final render so Lux gets a good base to start from. As Paolo has mentioned numerous times you have to light for the camera so the same as photography if you light your scene & set up your camera correctly then you should get the result you was after. Plus things like volumes/glass/metals & so forth have the biggest impact on render times (along with complex LEM's).

Regards

Lee
Windows 10 x64, Daz Studio 4.9 x64, Poser Pro 11 & whatever the current version of Reality is :lol:

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banditcameraman
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Re: Adding oomph to your rendering time

Postby banditcameraman » Tue Aug 30, 2016 1:01 pm


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banditcameraman
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Re: Adding oomph to your rendering time

Postby banditcameraman » Tue Aug 30, 2016 1:09 pm

Last edited by banditcameraman on Sun Oct 02, 2016 5:11 am, edited 1 time in total.

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fuzzy70
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Re: Adding oomph to your rendering time

Postby fuzzy70 » Tue Aug 30, 2016 2:09 pm

One thing worth noting about my previous post about Lux is when it is set to linear does it actually replicate as a real digital camera sensor or the film on a traditional camera. By that I mean on a real camera the higher the ISO the more grainy/noisy the image, same with the Aperture in that on a real camera it alters the DoF however there is no way of changing the DoF in Lux other than via Reality or manually editing the .lxs scene file. This is not Lux specific as it's pretty common on a few PBR renderers.

Perhaps because Lux & other PBR renderers are just software they are not limited by the physical properties of a digital sensor (voltage/noise ratio) or film grain (fast film/more grain) so you can whack up the ISO without introducing noise.

Again all hypothetical as while I understand the principles I do not know the code or implementation.

Regards

Lee
Windows 10 x64, Daz Studio 4.9 x64, Poser Pro 11 & whatever the current version of Reality is :lol:

Gederix
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Re: Adding oomph to your rendering time

Postby Gederix » Wed Aug 31, 2016 10:21 am

So I have been playing around with this overexposure hocus pocus voodoo magic and I am seeing... interesting things.

While my current scene is not rendering faster in the samples/pixel sense probably due to the aforementioned multiple meshes and emitters (I am using the power light strategy) it is resolving much more quickly per sample. Also, because of the cranking of the iso my scene has taken on a more interesting dynamic, it is more vivid, almost like I have applied a film setting. And, I went back to making all the flames in my scene emitters (dzfire torches) and even though previously this flooded my scene with noise that got worse over time, with this technique I am not experiencing that problem. I am seeing a grain but it is in fact resolving. This with four mesh lights and five torch flame emitters.
The biggest surprise though was that cranking the iso to 6400 did not cause the scene to wash out, which is what I was expecting. I was able to adjust the scene simply by turning down the lights/emitters, I was even able to remove a couple of mesh lights that the new exposure setting had rendered superfluous, I am guessing because of the increase light sensitivity, bounce and spill fill the scene with ambient light that previously did not exist or was undetectable by the camera at standard iso settings.

I am going to tinker with this further, pretty cool and unexpected results so far, thanks for coming up with this Banditcameraman!

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Nathanomir
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Re: Adding oomph to your rendering time

Postby Nathanomir » Wed Aug 31, 2016 4:03 pm

Well, this certainly is a time saver. My aging laptop can reach 1000 s/P in decent time, but not with decent clarity. An image running now started this morning. I used Light Strategies (necessary for the point lights in the candles -- too many light emitters chokes my machine), and overexposed, but only to ISO 2000. At 1000 s/P, it looks clear, but I'll let it go to 2500. The last scene I ran reached 5000 before it looked this clear (and I won't tell you how many nights that required).
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rattletat
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Re: Adding oomph to your rendering time

Postby rattletat » Sun Oct 30, 2016 1:10 am


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banditcameraman
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Re: Adding oomph to your rendering time

Postby banditcameraman » Sun Oct 30, 2016 2:21 am

Hi rattletat,

The skin itself has been modded with . The stretchmarks were added in Photoshop and "saved as" another name, then swapped out in the Materials tab. Aside from stretchmarks, moles and other blemishes can be added. While the Bundle is applicable from G2F (with converter plugins), Genesis, V5, M5, V4, M4, there is currently no way to apply those resources to G3 figures, although Zev0 is supposed to be working on a skin builder set for G3.

Sadly, the skin in the render also has AJ's Bloodvessels, which are no longer available, and may have been in fact sold to a content creator, although that is speculation based on observation.

Because the character's shape and skin has been heavily modified customized, sharing the scene file would yield error messages and not work, even if the same assets were owned as Reality would be looking for file names in the locations assigned (my Daz, Reality and files are on Drive D) :cry:

I'm sorry if this is disappointing but on a more cheerful note, Nathanomir and I are working on recipes for more better skin renders- he's actually pretty much done with G3 and I'm working on the recipes for Generation 4, Genesis and Genesis 2 as those earlier versions have similar settings.

Hth! :ugeek:


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