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Layer Offset or Tracking Program?

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Chris Hayner
Layer Offset or Tracking Program?
on Aug 15, 2005 at 11:17:46 pm

I'm doing a shot for a client where the camera pans to reveal a city on fire. The camera would start on a person and pan around to the city. The effect wouldn't start till the camera panned around and the edge of the building in the city is seen.

My question is, is it better to do this shot using the layer offset or use a tracking program like Smooth Running Gun? I played around with the offset but when I thought I had it right, the emitter wouldn't stay in the same place. It would move around. Any help and instruction would be greatly appreciated.

Thanks,
Chris


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Aharon Rabinowitz
Re: Layer Offset or Tracking Program?
on Aug 16, 2005 at 4:01:32 am

The offset is used to simulate a moving camera - this means that an emitter will move artound the screen without appearing to be dragged (i.e., leaving a motion trail of particles).

The best use of this is to pick an item in the shot that you want to set as the point to be tracked (Something there the entire time, which moves across the screen or up and down or whatever). If the camera pan is smooth from begingin to end, you can do this by hand. if not, and it moves around at different speeds or directions, you should motion track the object with program like Smooth Running gun or after effects. Then import the position data into the layer Offset.

Please note - the object being tracked is not necessarily where you're emitter is going to be. It's only used as a camera reference point. You can bring in seperate tracking data for the emitter if you need to (like if your emitter is moving around while the camera is panning.

----------------------------------------
Aharon Rabinowitz
aharon(AT)yahoo(DOT)com
http://www.allbetsareoff.com
----------------------------------------
Creative Cow Master Series DVD
particleIllusion Fusion Volume 1
available @ http://www.pIllusionFusion.com


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Chris Hayner
Re: Layer Offset or Tracking Program?
on Aug 16, 2005 at 11:17:26 am

Aharon,

Thanks for the response. The part of the shot where the emitter is bieng placed isn't always in the shot. the camera starts on a character running into frame towards the camera, as he reaches his mark the camera pans around 180 degrees to show the city with smoke colums rising in the city so does your advice of picking one point that is always there still aply?

This has been a part of PI that I have always tried to learn but have had little success.

Thanks, Chris


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Aharon Rabinowitz
Re: Layer Offset or Tracking Program?
on Aug 16, 2005 at 12:46:24 pm

It still applies. If you are working with a tracker, You need to have a point that you are tracking for this at all times - Since the object you are tracking moves off screen, I'm not sure you could do this reliably with particleIllusion alone.

I'd love to hear otherwise - since this is the kind of thing I ALWAYS do outside of pIllusion - usually in After Effects.

If I were tracking this with Adobe After Effects,I'd find a point I could track for part of it, then find another point I could track when that disappeared. As long as the crosshairs stay in the same place, the tracking region (which is actuially seperate from the crosshairs), even if moved around several times to find better tracking areas, won't effect the position of the crosshairs, and therefore keep the track smooth.

Not having used Smooth Running Gun, I have no idea if it could do that. But if it can, then you need to do a track with several steps where you change the position of the trackeing region, but keep the track point in the exact same spot.

Does that make any sense?

----------------------------------------
Aharon Rabinowitz
aharon(AT)yahoo(DOT)com
http://www.allbetsareoff.com
----------------------------------------
Creative Cow Master Series DVD
particleIllusion Fusion Volume 1
available @ http://www.pIllusionFusion.com


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Alan Lorence
Re: Layer Offset or Tracking Program?
on Aug 16, 2005 at 12:54:44 pm

There's a Layer Offset example in the docs that explains how to change the reference point. It's called "Break".


Alan.
wondertouch


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timoteo
Re: Layer Offset or Tracking Program?
on Aug 17, 2005 at 1:43:16 am

Whoopsie! Sorry, missed your post Allen. Faster then the human eye ...


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timoteo
Re: Layer Offset or Tracking Program?
on Aug 16, 2005 at 10:45:54 pm

Can't he just use the break function to achieve this? Unless I'm misunderstanding the question. You just use break and then choose a new object to track, repeat ad nauseam.


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Aharon Rabinowitz
Re: Layer Offset or Tracking Program?
on Aug 17, 2005 at 1:56:51 am

I should read the manual once in a while myself...

Sorry about that.

----------------------------------------
Aharon Rabinowitz
aharon(AT)yahoo(DOT)com
http://www.allbetsareoff.com
----------------------------------------
Creative Cow Master Series DVD
particleIllusion Fusion Volume 1
available @ http://www.pIllusionFusion.com


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Chris Hayner
Re: Layer Offset or Tracking Program?
on Aug 17, 2005 at 3:36:13 am

Aharon,

How would I go about getting the the position data from AE to PI? What do I need to copy or export? I have After Effects 6.5 and would like to see the way you would go about doing it. I tracked the footage in AE and now don't know what to do with it.

Thanks,
Chris


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Elvis Deane
Re: Layer Offset or Tracking Program?
on Aug 17, 2005 at 4:00:10 am

I'm no AE expert, but I believe what you do is apply the tracking info to an object as you normally would (say to a new solid). Then open up that object's position info so that you see all the keyframes, select them all, and Copy.

Once inside pI, right-click on the emitter you want to apply the motion to, and Import>Position Data and choose the version of AE you're coming in from.

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Aharon Rabinowitz
Re: Layer Offset or Tracking Program?
on Aug 17, 2005 at 4:03:34 am

If you are tracking camera motion as we've been discussing, do that step (of importing position Keyframes) on the Layer Offset property, not the emitter. Only apply that position data to the emitter (as Elvis directed)if you want the emitter on that particular spot (the crosshairs).

----------------------------------------
Aharon Rabinowitz
aharon(AT)yahoo(DOT)com
http://www.allbetsareoff.com
----------------------------------------
Creative Cow Master Series DVD
particleIllusion Fusion Volume 1
available @ http://www.pIllusionFusion.com


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Chris Hayner
Re: Layer Offset or Tracking Program?
on Aug 18, 2005 at 12:52:22 am

Thanks Elvis, Aharon, timoteo and Alan

I tried tracking the footage in AE and importing it into PI. It work very well. Now I'm trying to figure out how to mkake it a little smoother. The emitter in PI moves slightly left and right as the camera is moving until it stops the pan. I tried different settings and tracking points but haven't got it quite figured out yet. I've also tried the smoother but that didn't seem to do much. But, much thanks for the info.

Chris


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Aharon Rabinowitz
Re: Layer Offset or Tracking Program?
on Aug 18, 2005 at 3:30:06 am

try turning on motion blur in pillusion (view > Project settings).

Also it could be that your footage is interlaced and that's what is causing the problems you are having. Tracking Fields issues usually manifest as a jitter in the trackers position. In your motion tracking options try setting it to "track fields."

----------------------------------------
Aharon Rabinowitz
aharon(AT)yahoo(DOT)com
http://www.allbetsareoff.com
----------------------------------------
Creative Cow Master Series DVD
particleIllusion Fusion Volume 1
available @ http://www.pIllusionFusion.com


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Chris Hayner
Re: Layer Offset or Tracking Program?
on Aug 22, 2005 at 5:50:50 pm

Aharon,

Thanks so much for the advice on the tracking. I still wasn't really getting smooth motion even with the Track Fields selected. Then I got your DVD in mail and the first tutorial I watched made me realize what was wrong, I wasn't starting the track at frame 1 and I didn't have a keyframe at frame 1. As soon as I did that, it was smooth, so thanks for having such a great dvd resource.

I do have another problem though, the emitter is offscreen for the beginning of the shot in PI, when I insert the offset and say the effect starts on frame 60, just before the emitter turns on around frame 55 or so, you can see the full emitter in the right hand corner for a few frames before it slides into place where it belongs. Any ideas??

Thanks again,
Chris


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Aharon Rabinowitz
Re: Layer Offset or Tracking Program?
on Aug 22, 2005 at 11:50:56 pm

Assuming I understand correctly, that your emitter is showing up on screen before it should, but once on screen does what it's supposed to - then you could try any of the following:

-try setting it to not be active until it should be visible

- set keyframes for visibility. Visibility = 0 until it should be on screen.

- just move it off screen until it should be on the screen. Sometimes you just have to keyframe position by hand to fix tracking problems.

Does any of this help?

----------------------------------------
Aharon Rabinowitz
aharon(AT)yahoo(DOT)com
http://www.allbetsareoff.com
----------------------------------------
Creative Cow Master Series DVD
particleIllusion Fusion Volume 1
available @ http://www.pIllusionFusion.com


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