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#1 Daneel

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Posted 07 June 2017 - 11:38 AM

Hey guys.

I'm trying to make a tracking shot following a ridden bike (many thanks to jamoram for that mod) but I'm having problems. Does the camera movement ease in an ease out? by that i mean, does it take a little time to get up to speed and then does it slowly lose speed at the end of it's move (like the cars do when you have their movement set to 'smooth start and stop')?
It doesn't seem to matter what I do, I can't make the camera track at the same speed as the bike. any help would be greatly appreciated.



#2 jamoram62

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Posted 07 June 2017 - 05:24 PM

I was not sure about this subject, so I've made some quick tests by using:

* a mobile object (a fireball) moving on a lineal trajectory at high speed and at constant speed, and

* two cameras tracking it:

- fixed at its starting position

- moving along with the target prop, following it to the ending position

 

In both cases, no inertia was observed during the tracking, and the target was kept in the same relative position inside the field of view at any time.

 

Maybe we're using different tracking procedures?

 


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#3 primaveranz

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Posted 07 June 2017 - 06:33 PM

Maybe one of you is panning and the other tracking? 


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#4 jamoram62

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Posted 07 June 2017 - 06:43 PM

Actually, I've tried both:

 


- fixed at its starting position

 

That is, panning + tracking

 

 

 

- moving along with the target prop, following it to the ending position

This is travelling + tracking


ars longa vita brevis - Hippocrates (attributed)

 

If you want to tell jokes then use Muvizu; if you want to make 'Movies', use iClone; but if you want to tell stories, use Moviestorm - PrimaveraNZ

 

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#5 Daneel

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Posted 08 June 2017 - 08:01 AM

Maybe we're using different tracking procedures?

 

Yes. Maybe we are. Yours clearly works so can you let me know your procedure please?



#6 jamoram62

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Posted 08 June 2017 - 04:42 PM

I've made some new more exhaustive and precise tests.

 

As the target, I've used a fireball moving along a 15 meter trajectory in a second at constant speed, a speed high enough to expose any possible latency in the response of the cameras tracking/movement.

 

I have used 3 cameras, all them arranged and/or moving along a parallel 4 meter off the target's trajectory:

1) Tracking the object and fixed at a mid-point of the trajectory

2) Tracking the object and fixed at the starting point of the trajectory

3) Tracking and moving along a parallel trajectory to that of the target,

 

The takes for the three cameras are shown in this clip: https://drive.google...dVZWWDFacTJjc3M

 

 

And a video showing the arrangement and movement of the target and the cameras: https://drive.google...aWJSdzBDWm1COHM

 

Finally, an archive with the test movie itself: https://drive.google...M3lXTE1wODNqRG8

 

My conclusions:

- In every test, the camera has not problem to track correctly the target, keeping this in the designed point of the field of view.

- Panning (rotation of the camera) seems to have no latency at all and the tracking is immediate.

- Travelling (displacement of the camera), on the other hand, seems to have a certain latency, ie, requires a time for speeding up  and slowing to stop at the end of the trajectory: you can see in the second video, that when the target starts moving the camera is left behind, then accelerates and even manages to overtake it.

 

 

So it looks like, at least when moving at high speeds, the travelling movement is not uniform, if that was your question. But again, in every case the target was perfectly tracked all the time.

 

 

 

 

 

 

 

 

 

 


ars longa vita brevis - Hippocrates (attributed)

 

If you want to tell jokes then use Muvizu; if you want to make 'Movies', use iClone; but if you want to tell stories, use Moviestorm - PrimaveraNZ

 

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#7 primaveranz

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Posted 08 June 2017 - 06:44 PM

I wonder if the OP was targetting the bike or the rider?


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#8 jamoram62

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Posted 09 June 2017 - 05:51 AM

Would it make any difference?

 

My guess (and the OP's) is his problems are caused by the camera movement, not being uniform and at a constant speed, but accelerating at the start and decelerating at the end.

 

Anyway, the procedure for tracking I'd recommend to use is as follows:

0) Create the moving animation of the target along its path.

1) At the start point of the target trajectory, insert a new shot targeting the asset or character you are intended to track. Save it as a "Jump camera" (button with scissors and a red triangle)

2) Now, without moving the time cursor, edit the shot and then, without moving the camera, move  the time cursor forward: the camera will now move itself following the target. Whenever you feel appropiate, save the new shot as a "move camera" (button with an arrow and a green triangle)

3) Repeat the procedure described in step 2) until the target stops moving or no more tracking is required.

 

An example of results with this procedure: https://drive.google...SXJoYVJRMXFnRms

 

But, again, as it can be easily noticed, the movement of the camera is not uniform, but it speeds up and slow down for every segment of its trajectory tracking the target. This clip demonstrated this more clearly:

 

https://drive.google...N3lnb24xd3MzSjA

 

This time, the target moves along a linear trajectory. The camera follows it; three shots has been created to this purpose: at the start, in the mid and at the end of the trajectory. Please note the acceleration/deceleration of the camera does not happens in relation to the intermediate shots.

 

 

The only solution I can think of would require using an unique tracking shot along a trajectory longer than needed and discarding its initial and final portions.

 


ars longa vita brevis - Hippocrates (attributed)

 

If you want to tell jokes then use Muvizu; if you want to make 'Movies', use iClone; but if you want to tell stories, use Moviestorm - PrimaveraNZ

 

Shared addons & stuff for Moviestorm: https://drive.google...aTNsSFBuN0sxZHM


#9 Daneel

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Posted 09 June 2017 - 09:33 AM

Thank you very much jamoram. It is the travelling part of your experiments that is of interest, as that is where my problem lies.

 

So it looks like, at least when moving at high speeds, the travelling movement is not uniform, if that was your question

 

Yes, that was my question.

 

But, again, as it can be easily noticed, the movement of the camera is not uniform, but it speeds up and slow down for every segment of its trajectory tracking the target

 

 

This is exactly what happens with mine also.
 

The only solution I can think of would require using an unique tracking shot along a trajectory longer than needed and discarding its initial and final portions.

 

I'll give this a try. I appreciate the in-depth help.



#10 primaveranz

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Posted 09 June 2017 - 09:35 AM

I have often thought that there was a "lead in" acceleration when tracking figures, but not always. I suspect it may have something to do with which bone the camera has attached to.

Prims only have a single bone, whereas Actors and, I'm guessing, your bike, have more than one.

But admittedIy I have never taken the time to analyse it, I just find work-arounds when I'm "filming" ;)


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#11 jamoram62

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Posted 09 June 2017 - 01:22 PM

Agreed, that's part of the fun.

Besides, this leading & trailing acceleration thing, I think it's mostly an aesthetic decision by the designers, for there's no real reason for the camera behaving this way (it's not a physical object with an inertial mass thus requiring a force acting upon it to change its movement state), apart from simulating the real thing.

Anyway, it would have been highly desiderable this feature might be enabled or disabled at will.

ars longa vita brevis - Hippocrates (attributed)

 

If you want to tell jokes then use Muvizu; if you want to make 'Movies', use iClone; but if you want to tell stories, use Moviestorm - PrimaveraNZ

 

Shared addons & stuff for Moviestorm: https://drive.google...aTNsSFBuN0sxZHM


#12 Daneel

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Posted 09 June 2017 - 08:03 PM

Anyway, it would have been highly desiderable this feature might be enabled or disabled at will.

 

 

 

This.



#13 Daneel

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Posted 10 June 2017 - 10:45 AM

The only solution I can think of would require using an unique tracking shot along a trajectory longer than needed and discarding its initial and final portions.

 

 

This works perfectly. starting the camera approx 1.3 seconds before the portion you want to track and finishing the camera movement the same amount of time after you want the shot to finish solves the problem. Thank you.




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