Adding oomph to your rendering time

User avatar
Nathanomir
Posts: 135
Joined: Tue Mar 01, 2016 9:52 am
Location: North Texas
Contact:

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?
Sometimes, my wife wakes up grumpy. Sometimes, she lets me sleep.

Gederix
Posts: 99
Joined: Tue Mar 01, 2016 11:06 am

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!

User avatar
fuzzy70
Posts: 218
Joined: Mon Jul 13, 2015 9:38 pm

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:

User avatar
banditcameraman
Posts: 76
Joined: Tue Mar 01, 2016 7:27 pm

Re: Adding oomph to your rendering time

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

fuzzy70 wrote: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


What Lee said: I will do multiple tests (the last one, which is not posted here due to constest rules, was 7) one for light, the rest for getting the right material settings.

I have no idea if film response/film stock/camera settings work internally, like developing a picture (for those who remember it) or are post effects of an image :?: the fact that you can toggle the settings/light to improve a render, then return it to its original state might seem to indicate it's post. Although leaving overcranking too long for it to be effective might indicate otherwise. But I'm no coder and things like that are way beyond me.

What I can say is overcranking and using the Power Light Strategy whether on their own or together, under a number of conditions I've tested, works and will talk about them in a bit.

As always YMMV ;)

User avatar
banditcameraman
Posts: 76
Joined: Tue Mar 01, 2016 7:27 pm

Re: Adding oomph to your rendering time

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

owakulukem wrote:Bandidcameraman,
I'm wondering the purpose of setting the ISO up high? Does doing this render faster? If so, then are there optimal shutter speeds, and f-stops combinations that work better than others?
Thanks


Refer to Lee's post and please remember the following is what I think happens; it wouldn't be the first time I was wrong :lol: Am speaking from my personal observation and experience with Reality :mrgreen:

Renders are grainy because the pixels are still in the process of resolving. In the old forums Maestro Paolo used the phrase “starved for light”. By cranking up the ISO to the maximum the render is being bombarded by light. It speeds up the render in a way because the pixels resolve more quickly since they have all that light to “eat” and then some, so to speak.

Overexposing works even without using a LuxCore light strategy, although network rendering always helps because of the additional processing power. But even without the latter, you’ll still “force” pixels to resolve more quickly than rendering at normal ISO’s.

It’s possible there may be optimal shutter/f-stop combinations to further increase speed, but I’ve never used them and won’t. Here’s why: the shutter/f-stop are what my tutors in film school called “gross controls”, bumping one stop up or down causes a radical change. The ISO is a “fine control”, sometimes the apparent difference between stops seems to be negligible. So I keep the shutter/f-stop as the “control” group and tweak the lights to get the lighting proportions that I want, then overcrank. Admittedly there are times when I will tweak the light groups at the end of the render to see what else is possible, like the scifi mirror hall.

That said, I do have optimal settings for fuzzy70’s SingleIBL lights and for HDRIs because those light setups produce reliable, replicable results. Even so I will do test renders , usually to tweak material settings.

If anyone is interested, these are the settings I use; as always, it’s a starting point:

- SingleIBL: Film response: Advantix 100, ISO 100, 1/30 (if big circle) or 1/15 (if small circle), f/2

- HDRI (exterior) Film response: Advantix 100, IS0 100, 1/60, f/2 . It should be noted that since HDRI images vary widely more tweaking may be needed but those settings are, for me, a pretty good starting point.



Nathanomir wrote:Along similar lines, at what s/P do you recommend increasing the ISO to overexposure?


Personally I like to do it as soon as possible, usually after I’ve got the light gain mixed; within the two minutes after that. No later than five minutes or I might forget, which happened once. I left it and went to bed without overcranking. When I got up I was disappointed to see that it wasn’t as developed as other tests and since it was already 8K s/p overcranking it that late didn’t help and I killed it at 13 K s/p :roll:
Last edited by banditcameraman on Sun Oct 02, 2016 5:11 am, edited 1 time in total.

User avatar
fuzzy70
Posts: 218
Joined: Mon Jul 13, 2015 9:38 pm

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
Posts: 99
Joined: Tue Mar 01, 2016 11:06 am

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!

User avatar
Nathanomir
Posts: 135
Joined: Tue Mar 01, 2016 9:52 am
Location: North Texas
Contact:

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).
Sometimes, my wife wakes up grumpy. Sometimes, she lets me sleep.

rattletat
Posts: 57
Joined: Wed Mar 02, 2016 5:54 am

Re: Adding oomph to your rendering time

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

banditcameraman wrote:Example 2 (NSFW):

One G2F figure and SAV Mitchel Hair, each subdivided to 3. Light comes from Fuzzy70’s SingleIBL and Reality Mesh light provides a backlight.

Rendering time and resolution: 1.5 hours to 6-ish k s/p on one day, another 1.5 hours on another day for another 6-ish k s/p and an additional hour on another day for a total of 13k s/p with network rendering and overexposure to 6400 while rendering.

http://i.imgur.com/fqguBzp.png



Which skin is that? Im really interested on how the stretch marks on her hip appeared - adds realism to the figure. Is it just a matter of leaving a render running for 25k samples? Or Is it some reality materials settings? Or the particular skin is just that detailed?

If you still have the scene file, would you mind sharing it? I want to replicate the render with OpenCL GPU

User avatar
banditcameraman
Posts: 76
Joined: Tue Mar 01, 2016 7:27 pm

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 Zev0's Skin Overlay Merchant Resource Bundle (currently on sale at Daz). 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:


Return to “Tips, techniques, and recipes”

Who is online

Users browsing this forum: No registered users and 14 guests