Some advice to reduce render time

Hey guys and girls,

I’m trying to render some grass, and it turns out very well in my opinion :slight_smile: but the render time of one frame is about 30 minutes, so, maybe someone could look into my file and check if I can reduce the render time, because I need an animation of 250 frames, and this would take ages to complete, not to mention the continuous CPU load.

there is the .blend file

and this is one frame


The texture images weren’t packed with the file, but I gave it a shot anyway. I’m sorry to say that the strand rendering takes my CPU quite a while as well. I’ll bet you’ve tried these things too, but here are my results from a few different changes:

  1. I cut the render time in half by turning samples down to 50 from 100 and it still looked pretty good. There is a little “grain” in the dark areas, but in an animation that almost disappears if you animate the sampling seed value.

  2. My CPU is only about 2 percent faster on this scene with 64x64 tiles, but your results might be better at a different size.

  3. I rendered 19% faster by changing total Max number of bounces in Light Paths to 3 and Min to 1 (from 8 and 3). This did make the scene look a little darker.

  4. Turning off Cycles experimental CPU hair rendering completely changes the nature of the strands, but switching to GPU wasn’t half bad and cut another 45% off the render time.

  5. Checked the “No Caustics” box and had less than 1% difference in render time.

Do I get some kind of blender head badge for spending 3 hours on this? LOL

I think the “No caustics” only helps with certain scenes, with the light source behind a transparent object? does this apply for translucent also? I will not compete for the blender badge though… scared of long render tests :slight_smile:

Hey, thanks for looking into this, I wish i knew how to pack the textures into the file, but I’m new to all this Blender stuff :slight_smile: I wish I could switch to GPU rendering, but unfortunately my Mac’s video card isn’s supported :confused: I will try to make these changes as you suggested and see if I can improve my render time as well

By animating the sampling seed value you mean to set a keyframe and change it through the entire animation?

Yes, the way I animate the seed value is to keyframe the first frame with a 1 and then keyframe the last frame with whatever frame number it is (250, for example).