oh, smart ones,

I have a scene with 12,405 vertices and 9,766 faces which is a kitchen I'm designing for our house. I'm using Blender 2.76 on OS X 10.11.2 on an iMac Retina.

First, rendering quality: My samples are set to 18 square samples for 324 AA passes. I am using the Progressive Refine with 64x64 tiles. Rendering quality is basically like a 120000 ISO on a digital camera - very, very grainy. My "camera" sensor is set to 35mm DSLR.

I have no Blender Phong lights in my scene, everything is set for Emission material, with 7 object light sources, trying to replicate the existing, real-world kitchen. The material's Emission light strength is 11 for Surface and 7 for Volume. I have attached one such render output.

I have read most other questions that have to do with "grainy cycles, help!" or "fireflies, help!", but none of the fixes suggested there actually visibly improved the quality (of course samples helps, but when I bumped sampling to some large number I ended up with unrealistic times). Why don't we see any graininess in e.g. Sintel?

Second, rendering time: I have played with CPU rendering (8 threads since I have 8 cores), and also GPU rendering (this is my ATI video card). Overall, there is not much speed difference between my CPU and my GPU and both have extremely long times to render. For the 300+ samples above, I end up with about 40 minutes render time.

So, I said, it's definitely glass, reflections and what other complex objects I have in my scene. Therefore, I hid those from the render (no glass / windows, just plain cabinet boxes). Rendering time decreased only slightly.

How can I improve both issues? And finally, how can I "pack" the .blend so it contains the materials as well - if I want to, say, share it here for debugging?

Thanks, Virgil


  • $\begingroup$ Increasing tile size from 64x64 to 256x256 almost halved the rendering (20 minutes vs 38 minutes). $\endgroup$ Jan 6, 2016 at 4:46
  • $\begingroup$ You need to be using GPU rendering mode for this tile size to work. $\endgroup$
    – hawkenfox
    Jan 6, 2016 at 6:38
  • $\begingroup$ Use small tile size (like 32 or 16) for your cpu and high tile size (256+) for gpu. This will optimize your render times. $\endgroup$ Jan 6, 2016 at 13:16
  • $\begingroup$ Read this: sinmantyx.wordpress.com/2015/12/02/… and this: sinmantyx.wordpress.com/2015/12/02/…. Also you can optimize your materials with light path nodes and lighting with portals. If this doesn't help enough get a fast gpu (gtx 980 and above) [or a faster renderer - you want a bi-directional one] or render it on a web renderfarm (SheepIt). $\endgroup$ Jan 6, 2016 at 13:22
  • $\begingroup$ Thanks for the links! I am reading those with heightened interest. I've applied some of the compositor nodes described to my scene and it's visibly improving. The window reflection on the right is the only one that has to suffer (looks like I've applied a Gaussian noise filter - instead of the crisp reflection I get "bare"). $\endgroup$ Jan 13, 2016 at 4:52

2 Answers 2


For interior scenes, I find that using portals can work well. Set up an area lamp in a window enter image description herefacing into the room. Set it to portal, and set up another opposite of it on the other side of the scene. I also turn off caustics in my render settings, set light bounces no higher than 6-8 in most cases unless the first render just doesn't look right, and set my tile size to 16 x 16 to 18 x 18. Granted, I am using CPU, so this is more efficient for me I have found. For fireflies, I also set indirect clamp to a minimum of 1.01


For your last question on packing all the resources in the .blend file. This is the way to go:

  1. Go to File Menu.
  2. Look for external Data in the List
  3. On the pop up select "Pack All into .blend"

enter image description here

In regards to the grainy output of your image. My assumption from your written description would be to make sure you have enough light sources in the scene. In the real world there is no limitation to how many times a light can bounce hence it would not be wise to give the same amount of light and expect a totally similar result.

Most real world interior photography would also require the lighting crew to add additional light source to a scene to enhance the image.

  • $\begingroup$ should I add more meshes as light sources or regular Lamps (properly) configured for Cycles? $\endgroup$ Jan 6, 2016 at 6:55
  • $\begingroup$ From what I understand is that area light sources does create more noise as you will be shooting samples from a surface as comparted to shooting light source from a single point. The rays are more compact from a singular point and creates less chances for noise to propagate. So minimise the use of area light is what I will recommend. Only use them when it's really necessary. The real reason for area light at all, is when you would require soft shadows. $\endgroup$
    – hawkenfox
    Jan 6, 2016 at 7:08

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