Rendering for 5 days and is roughly only 50% complete.

[quizkiddonniesmith]

Just to give you some background, the rendering I am currently working on is an office interior, nothing too fancy, 35 chairs/tables, a few tv screens, and 26 rectangle lights.

The first rendering I had done took way too long to the point where I had to simply cancel as it was keeping my computer hostage for quite too long. The second I had done, I had removed all the rec. lights from being embedded in each fixture (light penetrating glass takes a while to process) so I shifted the lights in front of each fixture just a bit, made them invisible and shining on both faces and started rendering last thursday.

It is now Tuesday and one of the renderings is 65% give or take and the other (yes, rendering two, one on laptop, one on desktop) is only 50%.

I know there's no universal settings to render quickly, but if anyone has any tips, I would appreciate any further information.

By the way, the setting is at "GI_qmc_high" simply because the "med" setting wasn't enough quality. I had read to avoid qmc somewhere on this site after the fact.

I had also read that refraction can be changed to 2 (instead of the default 5) to speed things up. All I know is it's been 5 entire days running and its ridiculous. There's got to be something to change/alter/fix.

[han3d]

Re: Rendering for 5 days and is roughly only 50% complete.

keep anti aliasing off
and try threshold settings to higher and subdivision settings to lower

[dalomar_cg]

Re: Rendering for 5 days and is roughly only 50% complete.

So you're scene is an interior scene, with a lot of geometry, and a lot of lights...That is going to be a scene that is going to be a longer one but 5 days is way way way way way too long for it (in fact 1 day is too long as well).

Whoever told you not to use QMC (DMC now with the new release) is right. DMC is a brute force calculation, and will take longer and longer with the complexity of the scenes. Also, that visopt that you're using is extremely detailed and extremely precise. If you're looking for a very smooth render QMC is going to be very intensive to smooth out, which is probably why you said that medium wasn't good enough. Also, QMC is not very efficient for high resolution renderings, which is probably what you're working on.

I'll just go thorough some steps that will help you get a rendering much quicker than you got before.

1. Ditch QMC...change you're Primary Engine to Irradiance Map.
2. Use the following IR settings - Min/Max Rate = -4/-1, H.Shp SubD = 80
3. Secondary Bounces should be set to Light Cache (multiplier at .85 or .9).
4. Set Light Cache SubDs to 1500 or 2000, match Phases to the number of cores you have, enable Use For Glossy Rays
5. Image Sampler is going to need to be set to Adaptive QMC. Change the Max SubDs to 24. Make sure the Noise Threshold is at .01
6. Disable any Image Filter that is active.
7. QMC sampler settings - Adaptive Amount = 1, Noise Threshold = .01, SubD Mult = 1, MinSamples = 8
8. For each rectangular light, enable Store with Irradiance Map

All those together should get you started on bringing your render times down. If you post your target resolution, these can better be optimized if you're doing some thing larger than 1000x1000

[han3d]

Re: Rendering for 5 days and is roughly only 50% complete.

I try rendering at 1600x1200 resolution with 1 square light on
with irradiance map and light cache my render is good at 640x480
at 1600x1200 my actual product render is cool but there are splotches on the ground
which setting is primary for splotches
speed is important realistic simulation of real life is not on this case because my hardware is not fast

[Micha_cg]

Re: Rendering for 5 days and is roughly only 50% complete.

... never use adaptive amount 1, it can cause IM splotches. Better stick at 0.85.

[dalomar_cg]

Re: Rendering for 5 days and is roughly only 50% complete.

Yep, thats true...between .95 and .85 is good

[Micha_cg]

Re: Rendering for 5 days and is roughly only 50% complete.

Also it could help to replace so much rect lights by emitters, if possible. Maybe the IM samples must be set higher (SubD 100..200) to get a clean IM. The emitter are random sampled independent from the count.

[dalomar_cg]

Re: Rendering for 5 days and is roughly only 50% complete.

I think replacing the lights with Emmiters would actually slow things down. In terms of sampling and getting a good quality, actual light perform better. Of course higher HshpSubDs will get better quality, but the goal is to not have it take as long so I wouldn't recommend increasing them that high without knowing what the result is at a lower level.

[Micha_cg]

Re: Rendering for 5 days and is roughly only 50% complete.

It's something that must be tested. My experience is, that the LC calculation is slower if many lights are at the scene. So, we have LC speed vs. IM speed.
Only I know, it's a problem to render a scene with thousands of rect lights, but no problem to render thousands of emitter planes. If the emitters are not very bright and send not much light to the scene, than the IM calculations should not be a problem. But if each light act as bright "spot" light, than the IM calculation need much samples.

Some months befor I rendered a congress hall with many, many lights - using emitters helps.

If a ceiling is full of not bright spot lights, than all spots could be replaced by emitters and big hidden invisible light could be set over the whole ceiling to homogenous lit the room.

[dalomar_cg]

Re: Rendering for 5 days and is roughly only 50% complete.

Have you tried this with the Cutoff feature thats available with the lights now??? This speeds up calculations by preventing them from being calculated when they are to dim to affect that scene. Very useful.

[Micha_cg]

Re: Rendering for 5 days and is roughly only 50% complete.

Thanks, interesting, never used befor.