Cannot render...but can preview render?

I have had this issue with something that I’m working on for a while now. I thought that it was likely a RAM limit in my laptop (8GB), but since having build a computer with 32 GB RAM, I am still having the problem.

I am able to set all sub-surf/multires modifiers and all particle systems to BOTH preview and render, yet Blender crashes if I try to do a full render but renders just fine if I do a preview render. The memory usage when previewing the model is reported to be quite low on the latest version of Blender (< 3GB) and the number of triangles is definitely under-reported.

Is this a common thing? What might I have overlooked that could cause this? I have Blender set to use GPU to render, does this default to CPU if there are components that cannont be rendered on GPU? Seems odd that it would preview render but not full render.



does this default to CPU if there are components that cannont be rendered on GPU?


If you set render to GPU all you have is the video RAM.
For preview Cycles does some kind of simplify, subsurf 1 iirc.
But Blender should not crash, you only get a black render window.
Which video card do you have and how much VRAM.

Cheers, mib

Thanks, I will try setting to CPU. I think the fact that it was rendering preview fine whilst set to GPU (which has SSS, volumetrics etc) that I had assumed it was switching back to CPU. Lesson = don’t assume :wink:

I thought that simplify for preview is something that you can set as a uniform global value and turn it on and off via a check box in the render or world settings. I will double check what I have that set to, and if it does do what I thought it did.

As for the GPU, I have a GTX 770 with 4GB memory.



Good card, you can simplify for render in scene panel.
Close all windows, especially Browser can take huge amount of VRAM.
You can try to read out VRAM usage by GPU-Z, search for it.

Cheers, mib.

Thanks, I will try again tonight. I am going to do a thorough tidy up of my scene and check the settings of all the objects closely. Hopefully I can find out what it was that was causing the problem.