You need to track the shot so you have motion information from the shot, then apply the tracking data to the line. You could also remove all motion from the shot by stabilizing, not Warp Stabilizing the shot, then add your line, then reintroduce the motion to the shot. The best approach depends on the shot. Any chance you could put the shot up on YouTube or Vimeo so we could see it?
Here's a tutorial on the stabilizing technique that I talked about. It should give you the idea. The target would be the line:
Thanks for your help. I've posted a section of the footage that I'm working on at: aerial for animation - YouTube
I don't quite understand you're advice just yet so anything you can tell me will be helpful. I'm going to be needed to do this sort of moving line animation quite a few times on this project so I might as well learn it the right way. Thanks again.
I downloaded your video and tried a few options. Here's the easiest solution. Camera Trcking. It's quite simple really. Here are the steps:
- Import your footage.
- Select the footage in the project panel and create a new comp from footage (File>New Comp from Selection)
- Open the Tracker Panel (Window>Tracker)
- With the footage selected in the timeline select Track Camera from the Tracker Panel
- When the solution is complete make sure the trackers are visible by scaling them up a bit
- Move the CTI to the last 1/3 of the timeline or about 12 seconds
- Mouse around until you create a target the looks like it is lying flat on the scene, click, hold down the Alt/Option key while you are over the center of the target, click and drag to make it big enough to cover about 1/2 the shot
- Right click and select Set Ground Plane and Origin
- Right click again and select Create Solid and Camera
- Open up your solid and make it bigger
- Set the blend mode of the solid to screen or overlay so you can see through it
- Go to the head of the shot and make the y scale big enough to cover the starting point
- Go to the end of the shot and make the x scale big enough to cover the end of the shot
- Return to the start of the shot and start tracing the route with the pen tool
- When you get to the end of the shot add Effects>Generate>Stroke
- Set the Stroke Paint Style to On Transparent
- Set the stroke width wide enough to see
- Set the stroke color
- Animate the end of the stroke to draw on the line
That's about it
The project looks like this:
My original suggestion of stabilizing was too much work because of the perspective changes in the shot.
Here's a CS6 project file. You will have to replace the footage with the sample from YouTube that you posted.
Just a quick note to say thank you for your help. I'm working with it now and will post the result on youtube. Fingers crossed.