Cineversity

I am setting up a scene and I have some really slow renders. 15mins and up for rendering scenes which have three lights and I have configured the living day-lights out of the Physical and IG to speed it up as much as possible while keeping the noise down.

Never the less my renders are slow with just Physical or with Physical and IG. My output is 720p at 30 fps. I would like some advice on how I can speed this up.

I am using a Mac Pro (Late 2013) with 3 GHz 8-Core Intel Xeon E5, 32 GB 1866 MHz DDR3 ECC and AMD FirePro D700 6144 MB

My scene

Hi Raul,

That might be a longer discussion ;o)

First of all, I can’t see any animation.

Then the objects which have the Metal - Rusty Steel seems the first part that might eat up all your resources.

More importantly, the Physical>Basic>Subsampling is set to Fixed and 6. This is certainly a point to look into it. The value 6 stands for 6x6 samples per pixel. If set low, e.g., 2x2 you have 4 subsamples: So nine times higher rendering needed, as it is set to fixed. Fixed means here, it will subsample 36 areas per pixel, even if it is not needed at all. For each pixel—again: always. Set this to Adaptive and lower it to 4.

The Metal material, is reflective, that means, if I understand the DOP calculation correctly, it goes very deep, as the Physical renders as well the reflections in DOF, and if there are a lot, it takes a while.
To render black material that is even reflective as GI material—receive or produce, is not really clear to me. If you take that out, it might work faster. Perhaps render a few frames along your movie to see how GI works, and fake it them with some lights.
Reflective material “lives” from reflections, not so much from light. Of course I do not have your vision for the scene here, what aesthetically is needed.

On the other hand, there is a lot of procedural work done in your set up, perhaps getting the “city” as polygon model instead might help a little bit. Here it would be optional to bake light into it.

These are only “thoughts”, I do not have the render-power to explore each of them and more importantly all of them in combination.

Perhaps a Post DOF rendering with a depth map (I saw you have set up one in the camera (the near and far are only for post, its not connected to Physical cameras at all). I suggest that as your Camera 1 has a full-frame sensor setting, at 50mm and F/4.0 Which means with the Focus setting of 19m, you are 3m away from the Hyperfocal point (see image), which means the DOF-blur is so minimal, that it can be done in post without problems (See image.) So shutting off the DOF in Physical and the GI options in the “Black - Metal” will help, but then the Sampling might be possible at 3 (3x3=9 and is a quarter [!] of render-time of the 6, if set to adaptive, it might be even much lower.

This should reduce your render-time, again: I see no animation.

Storing the GI cache is a good idea, which I notice in your set up already.

With all the settings I found, I think 15 minutes was not bad, But I’m curious if you can get it below 3-4 minutes with the suggestions alone. ;o) Wild guess

Good luck

Dr. Sassi

That’s a lot of great advice to take into account. I will implement your advice.

Best
- Raul

Thanks for the feedback, Raul.

Lot of these render decisions are purely based on your aesthetically target. The method that is predominately responsible for this part should get the most attention. (I know that is easy to say, sorry about that)

As a side note, to suggest to experiment is not easy to suggest in detail. But what I do often is based on a black box, no reflection, to GI. This box cuts of part of the scene that I do not really need in the calcualtion, e.g. providing “reflections” or light. It cuts off GI rays earlier, instead of exploring the scene with no result.

My best wishes

P.S.: I needed some time to carefully check an idea. It is a very basic and simple idea. Normally I would suggest the opposite, as low values might create a black area in the reflections. Since your material is black I had to explore it deeply.

In the lower corner of the attached image you can see the three parameter that you might test out with the scene attached as well. I have set up an material with a very high energy, to make a point. The render settings are low to get fast results.

How strong is the “signal” needed for the final reflection? This would be the first value. The other two, especially the Reflection Depth is important to set as low as your scene allows it. Perhaps you might cut already a lot of render-time with optimizing these three.

Again, if the Reflection Depth is set too low, or the Ray-Threshold is set too high, black “holes” are the result. Normally not wanted, but here it might help to shave down render-time heavily.

Perhaps give it ten minutes to save hours of render-time.

:o)