Hi,
I’ve made an animation and I wanted to render a preview with motion blur.
I’ve started with 1920x1080px resolution and one frame was to long to render (6 min for a preview) . So I reduce the resolution by half to 860x540px but it’s still 6 min to render a frame.
Both render were in GPU with 1’500 sample on RTX 4090. Without motion blur I’m at 12sec/frame.
Why reducing resolution isn’t impacting the rendering time ?
That’s strange. But do you use the ‘preview animation’ option or create a normal render? The ‘preview animation’ option has it’s own sample-settings I think.
I personally never use the preview button above the animation timeline since it doesn’t add much if you can use the normal render box for a preview which also gives you more control.
Must say that 6 min for 1500 samples sounds like a lot. Not sure about your scene though but can’t imagine I ever had such render times with the 4090.
If you can/are allowed I can check your scene and see if I see something weird and test if it also takes such a long time here. Must say that if it is quite a dark scene it can also increase render times a lot.
Anyway, if you want you can send me a private message with a link.
Hi Oscar,
Like you, I never use the ‘preview animation’ option but like you said, the normal render window that I name ‘preview’.
Yes that why I post this topic. I know that motion blur needs lot more ressources, but I find passing from 12 sec without to 6 min with quite a big step.
Unfortunatly I’m not allowed to share the file that I’m working on due client privacy. I’ll try with a cube to check if I have same behaviour.
I’m facing now a new issu by cancel animation calculation. Render is stuck at 17/202 frame (1,5h for 2’500 samples) and canceling will loop and I never get back control.
EDIT: It seems that KS doesn’t handle well alembic animation. I have a deformed part from blender.
I tried to import just a cube with a simple 1 axis scale animation and import it inside KS. Same geometry, 12 polygons but completly differents render times. Even with deformation disable in the timeline, keyshot’s cube is 3s/2’500 samples, blender cube is 40sec. Time difference vanished when motion blur is disable.
That sometimes really takes forever. I’m not sure what it does but it’s almost like it cancels all frames one by one which were planned.
If I saved recently, I just quit the application with task manager but I’m not sure why it happens sometimes. It sure is annoying. I can understand it needs to put all back into the GPU again although that’s also weird since it’s in the viewport but cancelling renders is far from smooth.
Just see your edit popup. Does it make a difference if you remove the nurbs from the Keyshot cube?
I reboot my computer and no more calculation bug.
EDIT: No, it still freeze at 100% of a frame and can’t pass to the next.
I’m used to save before start render to be able to kill KS process during the rendering.
About the motion blur, I’m quite sure that’s linked to the alembic deformation. I’ve no idea on how to fix or get around that issu, instead of manage blur in post. AE is not that good enough for me so I’ll have to dive in DaVinci I guess.
With such a difference in render time I think it’s indeed best to do the motion blur in post. In DaVinci you’ve a few ways to do motion blur, one is simple/fast and you use the color tab and the other one you use the fusion tab which is more a refined way of calculating the direction of objects. Takes much longer but is also much more precise.
If I’ve some time I try to check some alembic animation and see what happens in Keyshot. I’ve used it once, but it didn’t really have deformation included.
I’ve read on a reddit thread that render the animation at a higher frame rate to have more images on high speed sequences can help making the motion blur in post.
I think I’ll dig in that direction. Render at 75 fps is 3 times longer, that’s still less than make it directly inside KS.
If I want to optimize, I’ll have to anticipate high speed sequences by making motion 3 times slower and speed up those parts in post in order to not over render slow sequences.
You could also use Topaz Video AI to double the fps in of your footage. That gave me great results in the past but that will obviously depend a bit on the kind of scene. Since you want to use motion blur, I think you should try it since it will save you a lot of time.
It can also upscale video and I sometimes had a better video with the upscale than before. It works with AI models and I’ve the feeling it helps if it can recognize what the objects are.
It can render extra frames in a video but also in an image sequence (that’s how I always render animation from KeyShot).
Think there’s a trial you can download on the TopazLabs website.