Hi,
To the point. Why Eevee in the same project, sometimes render a frame in 3-4 seconds, and the other time 12 seconds, and sometimes even 22 seconds. With no changes. Render by render, not in viewport.
Is this a bug?
Also with screen space reflections, or without, the time is the same. Attaching render setttings. Maybe someone can help to find the right options, and why the render times differs that much from time to time.
Regards,
Kamil.
can it be related to shader compilation ? have you tried with an animation ?
This is animation project, it will differ? Animation render times per frame and just render a frame?
I think it’s an important information for debugging if you have random slow frames, or if there is a pattern …
Except about shader compilation that can take time on the first frame, render times should stay the same.
So if your GPU isn’t working on something else , it’s likely to be a bug.
When you make a render with Cycles, rendertime is not always the same for same frame.
It may because something cached at first render is just reloaded.
It may be because you run another app at same time and task priority was not the same.
It may be because OS or driver’s upgrade or Blender’s upgrade.
Not the same conditions will not give same result.
It happens sometimes. But more or less 5 seconds on a Cycles render of several minutes will not alarm you.
On EEVEE that looks like something goes wrong. But that may be same cause taking same amount of time.
You should obtain same result under same conditions. But same conditions means that you always run only blender on computer, render same scene and compares rendertimes of same frame.
It is legitimate to obtain different rendertimes for different frames of animation. Camera moves, objects of scene move, meshes are deformed, lamps illuminate geometry differently producing different reflections and shadows. What is computed is different, times of these computations may be different.
Now I append the same project to a new file. Leave all the setting apart from enabling screen space refelction, change the resolution to 4k. So basically 64 render samples and 3 indirect bounces, which is higher than the original file, and the render time is max 5 seconds.
Then I’ve changed the samples to 30, and run animation render. About 6-7 max seconds per frame.
Something is wrong, why old file which is the same, with lower settings, take much more time to render, than the new one?
Also after completing the render samples (eevee counts samples) on new file render finish right away, in old file after completing samples counting, render hang for few more seconds.
Testing further.
Hi again,
Something really is off. I’ve tested the freshly appended scene from the old one. At the beggining, good even 1 sec rendering for 4k frame, and later… 12? And I don’t touch nothing! Developers need to investigate.
Edit: Even with 1 sample it take 9 seconds to render.
Edit2: It seems that the resolution is the cause. HD render blast quick, 4K need much more time, also after samples are finished computing, it stiil hang for few seconds in 4k. Any solution?
Does an animation with old file also take 6-7 seconds per frame ?
That would be possible that 2 seconds difference is due to file writing on your hard drive.
It probably had to have a relation with memory consumption. Latency is probably relative to the need to free memory.
Again, 10 seconds on a Cycles render of 10 minutes was not judged significant by developers.
They will have to find what happens for EEVEE. But EEVEE is in alpha state.
The priority is to have its features simply working as it should before thinking about optimizing rendertimes.
We are supposed to wait beta release to make reports. There is no emergency. Stable release is more than one month away.
With old it even slows to 14 sec per frame. Also I know Eevee is in alpha and a lot still to do, but I’m just sharing My observations.
For animations, shouldn’t eeve only take as long to render as it does to move from one animation frame to the next? I find the Renders much slower (even when set to the same number of samples as viewport preview). OpenGL renders where super fast in 2.79.
Not really, since the viewport playback doesn’t calculate all the samples set in “viewport samples”. It skips samples and I believe does some noise reduction trickery to get the framerate up.
If you are refering to F12 renders I’d also assume that blender exports all data for rendering (a process in itself). Remember that there are several things (modifiers and simplify tab) that have different settings in viewport and render.
Hi, I still think that a lower quality render from an animation preview would be good for users with lower powered machines. An avi or mpg exported like this would be ‘good enough’ for some people.
May be command line rendering will be a bit faster…give it a try
