The question seems noob, but give me a moment, because I should know something about these things.

I am rendering a semi large architecture outdoor scene with buildings and nature surrounding it. The scene has 1.6 million vertices and I use Grow3D (https://www.thegrove3d.com/) and Graswald (https://www.blendermarket.com/products/graswald) addons to generate nature. I have multiple renderlayers with samples from 150 to 400. I use denoising feature.

If I render the scene using GPU with render size of 1920x1080px and with percentage scale at 200, the whole scene renders in 1 hour and 8 minutes. (Memory conception is 1.2GB).

But then, if I increase the percentage scale to 300, computers CPU gets noisy and rendering time increases remarkably. The rendering time estimation shows something from 8 to 10 hours.

And if I take a look to my task manager, the GPU conception bounces only from 0 to maximum 10 percent.

enter image description here I ran quick tests and my computer and Blenders GPU consumption hits closer to 90 or even 100 percent at lover image sizes.

So could there be some hardware limit which I am reaching, or do I just forgot something crucial?

Windows 10, Inter Core i5-7600 @3.5GHz, 16 GB RAM, NVIDIA GeForce GTX 1070 and Blender 2.79.

EDIT 18.9. Here is the link for project file: https://drive.google.com/drive/folders/1n5LKe6f5JNSsUuAUfwsZo6PrfdE0Kk0f?usp=sharing

Because of the link won´t be valid for too long, I will post images about the settings when reason for odd behavior is found.

  • 2
    $\begingroup$ Don't forget that if you double the dimension size, you are making the area 4 times larger. That alone slows down the rendering significantly. In your specific situation, there might be some other factors. Without you sharing the .blend file or at least screenshots of your scene and all relevant settings it will be impossible to determine the cause of the additional slow down precisely. $\endgroup$ Commented Sep 18, 2018 at 6:55
  • $\begingroup$ It is truth, and I tried to keep that law in mind. I will provide the whole .blend-file with current settings when I am back to computer. Super if someone has time to look the file. $\endgroup$ Commented Sep 18, 2018 at 8:08
  • $\begingroup$ Did you intend to write lover or lower or something else in the question above? The first choice is more interesting. $\endgroup$ Commented Sep 18, 2018 at 16:37
  • $\begingroup$ xD. Lower. Unfortunately love is missing what comes to this case. $\endgroup$ Commented Sep 19, 2018 at 6:31


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