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Spline View: Show Derivative (1st order, maybe more)

Moderator: Chad

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Chad
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Spline View: Show Derivative (1st order, maybe more)

#1

Post by Chad » Mon Jul 24, 2017 4:37 pm

For some functions, like the SourceTime parameter in TimeStretcher, viewing and editing the values in the Spline View is not optimal, as often it is the derivative of the value that matters most. Deviations from a certain slope are what the user needs to manipulate, not the actual change in values. It would be really swell if the splines could be switched to displaying/editing the derivative (which is already displayed as the slope).

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Adelson
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Re: Spline View: Show Derivative (1st order, maybe more)

#2

Post by Adelson » Mon Jul 31, 2017 7:31 pm

+1

In some cases you do not want to adjust the position, you want to adjust the velocity (1s order derivative) or the acceleration (2nd order derivative)

In the specific case of the Time Strech function, its derivative is the Time Speed, no?

So maybe if the Time Speed could be animatable and adjustable by splines (which at the present time is not) it will have the functionality you mentioned as the 1st order derivative.

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Re: Spline View: Show Derivative (1st order, maybe more)

#3

Post by Chad » Tue Aug 01, 2017 6:17 am

Time Speed has other issues, like what is the basis frame that the multiplication starts from? If that changes, you're screwed. And whatever the current frame value is is dependent on integrating all the previous frames. So changing the speed on frame 4 affects all the output value for all frames after that, even the ones with keyframes.

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Re: Spline View: Show Derivative (1st order, maybe more)

#4

Post by theotheo » Tue Aug 01, 2017 6:19 am

I never use timespeed, in FU or <MacCompositor>. Its easier with a curve you plot exactly where you want the action (or ref) to be. Oh; and I always have a text node handy thats showing me the 1st order derivative. Most retimes are given with refs in %

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Re: Spline View: Show Derivative (1st order, maybe more)

#5

Post by Chad » Tue Aug 01, 2017 6:29 am

For me, it's an issue where the curve in Spline View is mostly a 1/1 slope with very small deviations. So the upper left and bottom right of the graph space is empty wasteland. If I could just rotate the view by 45 degrees and zoom in, I'd be fine. Not just TimeStretcher either, you can see it with percent-along-path type controls too.

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Re: Spline View: Show Derivative (1st order, maybe more)

#6

Post by Adelson » Tue Aug 01, 2017 6:53 am

Chad wrote:And whatever the current frame value is is dependent on integrating all the previous frames.
But that will be the problem whenever you adjust the derivative of any curve, no?
You have to integrate (which is the reverse of the derivative) to calculate the original parameter on any specific time.