I want to achieve a slow motion effect during a non-cut scene, which means that the scene (with animations, rig-animations and maybe physics) will start with normal speed, has slow motion somewhere in it and then gets to normal speed again.

The only way I found to change the speed of the scene without manipulating tons of pre-set keyframes is to use the time remapping feature (e.g. 25:100), but I'm not able to set a keyframe to it, so it is permanently. How do I get a kind of temporary slow motion without cutting footage or rendering with 120+ fps and then composite the slow motion effect?

Thanks beforehand for taking time to read through!

  • $\begingroup$ How is the slow motion effect going to be triggered? Do you want it to simply slow down during a preset frame range, or should it for example be triggered by some property of an object? $\endgroup$ – user27640 Dec 1 '17 at 20:15
  • $\begingroup$ I want to achieve something like the time remapping, but animated, like at frame 28 slow down to 1/4 of original speed, at frame 64 speed up to original speed again. If it's easier to trigger it by an object's property, that would be fine as well. Main thing is to have control over the scene's speed including all physics/simulations/rigs (some of them don't have keyframes to be animated manually). $\endgroup$ – NGCHunter2 Dec 2 '17 at 13:30

All physics have some kind of setting that lets you control the speed at which they're run. This setting can be keyframed or assigned a driver, so for your case, keyframe it to 1.0 at frame 27, then to 0.25 at frame 28 and 63, then 1.0 again at frame 64.
If you want it to gradually slow down and speed up, set something like for example 1.0 at frame 20, 0.25 at frame 28 and 63 and 1.0 again at frame 70.
With particles it's set as the time between frames instead, but the idea is the same. I'll come to that.

For Rigid Body physics, this is located under Rigid Body World in the scene properties. This affects all rigid bodies in the scene.

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For Soft Body physics and Cloth simulation, it's set in the physics properties per object.

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For Smoke simulation, it's set in the physics properties for the domain.

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Fluid simulation is a bit special, as it runs over the entire range of frames being rendered.
The Start value defines what point in the simulation will happen at frame 1. The part of the sim that comes before this time has to be calculated, but gets discarded.
The End value defines what point in the simulation will happen at the last frame.
As an example, let's say you have a 10 second animation, and you want the whole fluid sim to run at one quarter speed, just set start to 0.0 and end to 2.5. These 2.5 seconds will be stretched to take the 10 seconds of your animation.
The Speed value speeds up or slows down like for the other simulation types.
These are set in the physics properties for the domain.

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For Particles, as I mentioned before, the setting controls the time between frames rather than a speed factor. To slow down, decrease the Timestep value, to speed up, increase it. To keep the accuracy, you may want to increase the Subframes value, to do calculations in between actual frames.
It's set in the particle settings per set of particle settings. One set of particle settings can be used by several particle systems.

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  • $\begingroup$ Thank you very much! That answered everything I was looking for! $\endgroup$ – NGCHunter2 Dec 3 '17 at 13:57
  • $\begingroup$ @NGCHunter2 Glad I could help, with both you recent questions. $\endgroup$ – user27640 Dec 3 '17 at 23:13

Enter the graph editor and move all keyframes by youst draging them together

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    $\begingroup$ Like I said, I don't want and I'm not able to move keyframes along, for I'm using physics (which I don't want to bake to keyframes for a 2+ min scene) and simulations, which can't get handled by keyframes well. $\endgroup$ – NGCHunter2 Dec 1 '17 at 17:22

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