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speed : preview vs. render

PostPosted: Tue Dec 04, 2018 11:34 pm
by protovu
Hello Fellow BlendOctaners,

My Octane render preview is fast. With a medium complex model which is using transparent surfaces, I can snap anywhere in the timeline and regardless and get a 1.5 image with about 50 samples.

Not so when I go to do an actual render with the same settings. Very slow.

I was thinking that this might be due to mesh compilation, but the same compilation occurs in Preview Renders, yes?

How can I emulate the speed of the Preview Render in an actual animation? Frames without Denoiser about 6 seconds. With Denoiser about 14 seconds.
I must be missing something obvious.........

Thank you for the help.


Win7 64
dual xeon
32 G RAM
970,980 Ti, 2x TitanX
Nvidia Driver -4.17
StandAlone 4
Octane_Server_4.0_-_16.3
Blender_Octane_Edition_16.3_2.79
protovu
Licensed Customer

Re: speed : preview vs. render

PostPosted: Tue Dec 04, 2018 11:48 pm
by ChrisH
What resolution is your render and how big is your "preview window".

I think it's the resolution that is most likely to be the reason to differences in "render times"!
Usually my preview area/window is not more than 1/4 of my screen (very rarely full screen), and my final renders are from 1080, to 4K, to more...

Re: speed : preview vs. render

PostPosted: Wed Dec 05, 2018 12:51 am
by protovu
Thanks for the response, Chris.

At your prompt, I just stretched out my preview to about 1920 x1080 , taking most of the secondary monitor.

The preview is still really fast. About 3 seconds.

The Render, at 1280 x 720 is about 12 seconds.

Doesn't seem to make sense, does it?

What really puzzles me: I don't see the lag from mesh compiling that I see in the actual render. After the initial compilation, the render just snaps into place as I move on the timeline.
This is what I want for test renders!

Re: speed : preview vs. render

PostPosted: Wed Dec 05, 2018 1:11 am
by grimm
Short of it just being a bug, have you taken a really close look at how you are setting up the object types? If you are seeing a lot of mesh recompiles, it could be the issue.

Re: speed : preview vs. render

PostPosted: Wed Dec 05, 2018 1:21 am
by protovu
Thanks, Grimm.

I am new to Blender, not to 3D. I am not sure what you mean by object types, actually. Primitives, for example?

If there is a recommendation on how to set up object types regarding mesh complement, please forward.

Even so, why would object types be a non-issue in the preview render? Same models and Keying.

Re: speed : preview vs. render

PostPosted: Wed Dec 05, 2018 2:08 am
by J.C
Take a look here:
https://docs.otoy.com/BlenderH/BlenderP ... yTypes.htm

Modifiers can slow down a lot compilation time especially CPU extensive like Subdivision surface. You can apply them before rendering an animation.

As far as rendering animation in viewport is concerned I wonder too why it does compile every frame during final render while in viewport it is not.

Re: speed : preview vs. render

PostPosted: Wed Dec 05, 2018 4:31 pm
by protovu
Hi J.C.,
The modifiers don't seem to slow the Preview Render at all.

It is as if in the Preview Render, the file is loaded and ready, regardless of which frame I am on.

And with an animation Render, the file is being reloaded for each frame.

This sure seems wrong.
Totally slows the process.
I would be very happy with the Preview Render output for an animation.

Anyone else experiencing this difference?

I will dig into the page you referred. Thank you for that.
Rick

Re: speed : preview vs. render

PostPosted: Wed Dec 05, 2018 5:37 pm
by J.C
It's always been this way since beginning. This needs some clarification from the developers.

Re: speed : preview vs. render

PostPosted: Wed Dec 05, 2018 5:59 pm
by protovu
Is there a way to push this question up the food chain?

I see no relief from designating object types.

Re: speed : preview vs. render

PostPosted: Wed Dec 05, 2018 7:13 pm
by J.C
I will forward this to Lino. He is closer to developers.