Kink in Velocity - Two keyframes of the same value create motion over time?

[zackd24374744]

This started appearing a few months ago for me. After 10 years of using AE, I've never encountered it, even under the same conditions.

Scenario:

Position Keyframe A (linear) is copied, moved (n) seconds in time to a point later in the timeline, and pasted. There should be 0 velocity, because it's the same keyframe value, right? To be clear, both keyframes are linear... so this should behave like a hold keyframe. But motion happens? And after opening up the value graph, I can see that a kink has formed between the two key frames. The only way to smooth out the kink is to increase the distance (in time) between the two keyframes.

Is this a bug?

Screen shot attached.

[Dave_LaRonde]

There are a couple of ways to resolve this:

First, make the outgoing keyframe in the timeline a Hold keyframe.

Second, go to the comp window, grab the keyframes' Bezier Handles, and straighten out the motion path.

[zackd24374744]

Thanks so much for your response.

First, make the outgoing keyframe in the timeline a Hold keyframe.

This works if I actually intend on keeping the object in place. But I used that scenario of the two keyframes with the same value as an an example, I also get this problem when I only have a little bit of movement on one axis. If I made my outgoing keyframe a hold keyframe, then I would not get the slight motion It happens with the distance between two keyframes is really short.

Second, go to the comp window, grab the keyframes' Bezier Handles, and straighten out the motion path.

Thank you for the work-around. But I shouldn't have to straighten out the handles every time I want a linear motion. This seems like a setting that I have incorrect, or a glitch.

For this particular scenario, this is what I see in my comp window:

[Roei Tzoref · Accepted solution]

it's one of the first quirks a user encounter when starting to use the software. one of the first thing I teach in Ae class is under preferences->general to check the option to "Default Spatial Interpolation to Linear". This will minimize the chance for this to happen. If this is after the fact, You can set your keyframes to linear by ctrl+alt and click on the actual keyframes in the composition panel or in the timeline panel right click on both keyframes->keyframe interpolation->linear.

More about it here: https://m.youtube.com/watch?v=rLdBTzkMa7k

[zackd24374744]

Thanks! This was the issue. To solve the problem at hand, I right clicked on the spatial keyframes in my comp window, selected "keyframe interpolation..." and changed "Spatial Interpolation" to Linear.

[Roei Tzoref]

Great! thanks for clarifying that the keyframe interpolation should be set to linear on "spatial interpolation". BTW in case you do want spatial bezier interpolation and to lose the drift then setting the first keyframe to Hold is the answer.

[DigitalSpatula]

Another great thing to do is change the default setting in the preferences: genereal to linear. see attached