How to optimize render for specific effect

Over two years ago, I plunged thousands of dollars into a computer and parts that I intended to use just for Blender. About two years ago, I found out I was going to be a father. All progress on anything outside a nursery stopped.

Now I have a fifteen-month old boy, named Preston. I’ve finally got him on his own, he can order delivery when he’s hungry, knows how to work Netflix, etc so I can again sit with my Blender machine, named Hope. Sure it’s cheesy; but I was younger then…

This image took 28+ minutes to render and I’m sure I can do better, but how?


It’s 52 layers with a modest Nodes setup controlling transparency. The basic computer stats are Core i7-3770 @ 3.5GHz with 32 GB RAM. 64-bit Win 7 Pro with the best graphics card I could afford at the time, the nvidia GeForce GTX 690 with two GPU’s @ 915 MHz (2GB GDDR5 dedicated video memory) and 1,536 CUDA Cores.

I’m sure there’s more information experienced users would need to know to help me, so ask! This computer was meant to really hum through projects. But it feels like I’m not utilizing its power even 60%

The specific effect, by the way, is this use of procedural for textures, transparency and colors to mimic volume.


I know. Another fat, little baby. It was worth putting 3D off for a while.

So, I turned CUDA on. That was a great change. It buzzes through geometry like crazy.

It also crashes on very few transparency layers. Very few. Maybe 3 or 4. And Volume. This is expected? What part of the computational equipment is responsible for what?

If Blender crashes on rendering, this is mostly caused by running out of memory…

Your GTX 690 is basically two GTX 680s in one card, with 2 GB of VRAM per GPU. While this theoretically adds up to 4 GB VRAM in total, both GPUs can’t share their memory - which means that you effectively only have 2 GB usable VRAM for your scenes. That’s quite little by today’s standards.

Could you share some of your scenes causing trouble? I’m sure that would help us finding ideas to optimize the render performance.

I will post a scene. I don’t have any file uploading account anywhere so that’s why I haven’t yet. Thank you for the response too! I did find this…

https://www.blender.org/manual/render/cycles/features.html

The latest documentation that answers the Q. Nowhere on that list is regular RAM which stinks because I sunk so much in to that feature. But the RAM on the video card is an interesting mention.

And here’s an answer I don’t quite understand:

CUDA:The maximum amount of individual textures is limited to 95 byte-image textures (PNG, JPEG, …) and 5 float-image textures (OpenEXR, 16 bit TIFF, …) on GTX 4xx/5xx cards, and 145 byte-image textures and 5 float-image textures on GTX6xx cards and above.
But I wonder if this explicitly tells me how many transparent cloud layers I can use in some mathematical translation.