track points - paint -add this path to another shape?

I have read the docs for motion tracking and trtack points and this is what I am trying to
achieve.

Step 1: draw thick line over lower third
Step 2: Add shape style-heavy liquid (this animated a heavy blob from left to right)
Step 3: Add track point behaviour to this blob shape
Step 4: create a circle on a new layer
Step 5: add track points to circle layer
Step 6: select blob layer as source for circle

What I am expecting is that the cricle will red the path data from the blob and mimic the
motion of the blob; but nothing happens

I am using 3.0 and wondering if I have misunderstood the track points capabilties?

Any suggestions welcome!

Ok, I think you've gotten confused on how the motion tracking works. I took your steps and created what I believed your are trying to accomplish. Here's how I did it:

Taking the paint tool, I drew a line across the lower third of the screen. Then I added a heavy liquid shape style which creates an animated painting effect similar to a creative cow tutorial I saw at:

[library.creativecow.net]

Now, since motion analysis doesn't work on the paint tool, I had to export what I have so far as a quicktime movie in the settings I'm working in and then reimport it into the project into a new layer. Since I now have the paint stroke as a self-contained quicktime movie, I simply deselect the paint layer as I no longer need it (but don't want to delete it).

Selecting the paint mov, I add the behavior Motion Tracking/Analyze Motion to it. Take the tracking point and place it on the head of the animated paint stroke and hit the analyze button. This step took awhile because the tracking point got lost several times as this paint stroke isn't an ideal thing to track.

After finessing the track I created a new layer above the paint layer and created a simple circle, moving it over towards the beginning of the paint stroke. Then I applied the behavior Motion Tracking/Match Move to the circle. For the source, I dragged the "analyze motion" behavior attached to the paint stroke and dropped it on the source well of the "match move" behavior.

Finally, I had to make an ajustment to the anchor point of the circle so that it was positioned correctly over the paint stroke and viola. The circle follows the tracked liquid "blob".

Hope this helps. Here's a quick movie of the result.





Andy

Nice job, Andy - great explanation, too.

Thanks for th help.
Maybe in a later release they will allow you to
use the spline path for the paint stroke as a
path for the circle.

Your explanation was great!



mark@avolution Wrote:
-------------------------------------------------------
> I have read the docs for motion tracking and
> trtack points and this is what I am trying to
> achieve.
>
> Step 1: draw thick line over lower third
> Step 2: Add shape style-heavy liquid (this
> animated a heavy blob from left to right)
> Step 3: Add track point behaviour to this blob
> shape
> Step 4: create a circle on a new layer
> Step 5: add track points to circle layer
> Step 6: select blob layer as source for circle
>
> What I am expecting is that the cricle will red
> the path data from the blob and mimic the
> motion of the blob; but nothing happens
>
> I am using 3.0 and wondering if I have
> misunderstood the track points capabilties?
>
> Any suggestions welcome!

Yeah, it's a bummer that you can't intuitively paste keyframes from one attribute into another. That would be very helpful in your case as you wouldn't even need to mess with motion tracking.

Andy