Important - When Rendering - Cut it all back
Patroklos
Posts: 533
in The Commons
Hello,
I am rendering a complex scene, it loaded with a building and many lights.
My computer is good but no Nvidia card.
First shot after 24 hours 61% converged.
Second shot, reduce number of lights but keep the scene bright, hide everything not in view of render, 11 hours 68% converged.
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I only add lights if I absolutely have to. There very good HDRIs out there that provide excellent lighting and (in my experience) render WAY faster than added light rigs. For indoor renders, you can often even do tricks like hiding the roof and/or off camera walls to get lighting from the HDRI. You can't always use HDRI only for lighting scenes, but with a little bit of tweaking, I find that I rarely need to add additional lighting besides the HDRI.
Yes, HDRI are faster but not always suitable.
I find indoor scenes the slowest, so I hid the roof and those walls not in view, plus cut out half of the lights.
I also note that lighting the scene as brightly as possible whilst still getting the right feel helps a lot.
Here's a few things I've seen in some of my renders and tests:
1. For indoor scenes, if there are no windows or anything like that in view I find setting the render to "Scene Only" and then hiding the ceiling and other walls and things not in frame to help quiet a bit.
2. If there are no windows or anything crazy in my scene I set the max path length to 6 or so.
3. Believe it or not, the angle of the camera matters. If you have a scene that's a high angle looking down it seems to render faster because there are less intense shadows below things to render since you can't see them. If you do a low angle looking up and your only light source is above you have dark spots and shadows like below your characters arm pits and this is really hard and time consuming to render. So try tilting your camera up if there's not a specific reason for a low angle.
4. Light the scene brightly and then do some tone mapping adjustments to get the right look.
5. Emissives that are in most scenes seem to add quite a bit to the render speed. I use the ghost lights to fill in light and what I do is set a spotlight outside a window to simulate the sun. Or if I want something more moody and less flat I use some spot lights and an hdri.
Hope this helps.
If you can't always do it the easy way, beat it over the head with hardware.
I have a couple of render boxes to solve render times, but I pretty much strive for realism, and light with how it would be lit in real life - if it's 100 light bulbs, so be it. I usually throw in an HDRI for the sky if there are windows or openings in the scene, or outdoors of course.
It looks like the next version on DAZ Studio needs to be an optimization pass. No new features, just clean up the code so it works more efficiently. I suspect the current rendering engines are inefficient and could use some serious speed/efficiency cleanup.
Thanks, max path length to 6? How much difference does that make to the quality? Is it visible?
I would welcome that assuming that you are correct.
I am so pissed off that my Mac cant be fitted with an Nvidea GPU. I purchased it just before Iray arrived!
I think this has to do with how the light falls off, so at it's default of -1 the light doens't fall off much and just keeps bouncing all of the place which makes things take a lot longer. I don't think it hurts quality too much if there aren't many reflective/windows in the scene/frame. If there are, then you might start seeing a dip in quality. But from what I can see it does help with the render times.
I'll give it a try, thanks
Max path length controls how many light bounces are allowed. -1 is the default, which is infinite bounces. 6 may be a bit low for some scenes and I haven't found settings over 11 to make a visual improvement.
You can always experiment with the value, but i have found 8 or 9 to be a good all round value if you don't want to rweak each scene. Values other than -1 do shorten render times.
I am trying 7 right now.
Presum,ably not actually infinite, since the process dos stop, but rather (I think) it bounces until it reaches a certain degree of attenuation, at which point the result is returned (on the grounds that any remaining modification to the colour would be slight). If my understanding is right then it might be nice to be able to set the threshold, as well as or instead of capping the bounces.
Unlimited rather than infinate!
A threshold would be more precise, if were possible, though that too might have its problems in that it could lengthen render times if set carelessly?
I have switched off one more light and turned the others up to compensate, I have reduced Max path length from -1 (unlimited) to 7.
At 11 hours the render was around 75% converged as opposed to 68% before these changes. The render quality appears good, and at the 11 hour point certainly better than the previous render saved at 11 hours.
That seems pretty positive.
I do whatever works fastest. I cheat comstantly since my computer is a laptop. I like to presently use sun and sky indoors with the ceiling removed. Sometimes I use hrdri or emissive. I usually hide everything in the scene but the visible areas.