Moho Forum

Hi guys,
please watch this video where I explain my problem to make the stopping of a car look more natural:

Correction: At one point, I said the camera is animated on 'smooth' (interpolation). I meant 'linear' instead!
PS: I ended up making all keyframes 'smooth' for the whole duration of the animation (for both camera and car), deleting those at the 8 sec. mark. That spaces out the duration of acceleration and braking. But now, I have the additional problem, that he appears to start driving - from a halted position - at the beginning of the animation. My intention was to show the last leg of his journey. That means showing him already driving at the beginning of the animation. Maybe the solution is to make the first second linear and the rest smooth.

I'm still not sure what kind of stopping you're looking for but there are several ways to do it.

One could be the spacing of the keyframes. From linear to smooth and to smooth again. Set the start and end position (linear to smooth). Then you add the kf to set the breaking point (smooth one) on the scene, and then move it further to the left on the timeline.

For the bezier ones, as depicted...

You may swap the lengths (but not the angles) of handles on the last 2, depending on the stopping you prefer.

I'm still not sure what kind of stopping you're looking for but there are several ways to do it.

What I was looking for was linear movement for the majority of the animation, followed by a 2 sec slowing down phase leading to a stop.(without any acceleration in between)

I'd set the keyframes to show the motion I need and then limit the scope of rendered frames.
The scene does not have to start from fr1 since we can set the first and last rendered kf's, on timeline.

p.s.
motion on depicted beziers acts like linear and then slows down to a halt.

Try to use a path for the car, set when you want the car to start moving on the path, set when you want the car to start slowing down on the path, set when you want the car to stop moving on the path, then set the first two KF to linear, and the last one to ease out, this should do the trick!

You could also manually key frame the slowing of the car using the path tool and onion skin, that would give you more control!

The best way for a convincing movement is to have as few keyframes as possible. In this case I'd have 3:
linear - smooth - smooth
Since this should be a layer movement you can see the intervals in project view, you could adjust the middle key to make the spacing before and after evenly.

if you're aiming for a realistic "distance / time" curve for deceleration -- that's NOT a linear relationship.



example here is 20 seconds to stop from 30 m/sec (about 110kph) reducing the speed linearly (dropping by 1.5 m/sec each second) - cumulative distance (m) is on the y axis. IOW here, in the last 6 seconds you travel about as far as you did in the first 1 second.

this same basic curve shape (it's a quadratic) works for all acceleration / deceleration scenarios.

And then you can start to think about driver behaviour as to whether you want this to look like a "posh chauffeur" or a "boy racer"...

Hugging_Bear wrote: ↑Thu Jan 16, 2025 2:33 pm ...
What I was looking for was linear movement for the majority of the animation, followed by a 2 sec slowing down phase leading to a stop.(without any acceleration in between)

Are you sure the unexpected acceleration is not caused by the combined motion of the car & the camera(zoom)?

having these two work simultaneous complicates matters.
I would first try to create the car motion with an ease-in (or via the spline handles),
and when you have it working as you like, add the camera move. All while you pay close attention no weird motion illusions start to re-appear.

Oh yes, very good advice: quite often I had camera moves and layer animation cancel each other out or give very weird results. Recently I had a multiplane setup following a walking character, all was working nicely until I added a track-in of the camera: suddenly the muliplane layers stopped or were moving backwards against the walking characters.

I followed SlowTigers advice of having only 3 keyframes and it works fine. Between keyframe 1 and 2 I have a linear movement to show that the car is already moving by frame 1. This phase lasts only the first sec. of the animation, followed by a smooth movement between keyframe 2 and 3, in order to get the slowing down effect before the car stops.
Thank you for the inputs. (sorry for my late reply)

Glad to hear you've managed to make it work.
Though, it's exactly the same to what I suggested in the initial reply / apart from plan B for beziers.
Would you be so kind to explain to me, what did I make unclear / for future reference? Thanks in advance.