View Full Version : Making a balloon point at a moving race car


Tripp Woelfel
June 29th, 2008, 07:16 PM
Not sure whether this can be done in PP or AE in CS3, so I'll start in this forum.

I want to float a balloon above a race car on track with the pointy part aiming at the car. The pointy part needs to track the car movements as I pan the camera to keep up but the balloon itself should not move. If you're familiar with NASCAR broadcasts, you've probably seen this type of graphic.

Is there a simple way to do this in either PP or AE? It's gotta be fairly simple to repeat the function as I will probably want to use this effect 6-8 times or more in a 40 lap race.

Edward Carlson
June 29th, 2008, 08:39 PM
In After Effects you can use the motion tracker. Go to the Animation menu > Track Motion. This opens the motion tracker palette. From there you can set the point to track, and the target to apply the motion to.

Tripp Woelfel
June 30th, 2008, 06:27 PM
Edward... I thought about that, and have used it in the past. But wouldn't move the box too? What I want is a stationary box (balloon) with the end of the downward pointy part located near the moving car.

Even if motion tracker is the way to do it, it's a fairly time-intensive effect to apply and may not be practical to do.

Any other options?

Edward Carlson
June 30th, 2008, 10:31 PM
What you could do is apply the motion tracker to a null object, then link the point of the balloon to the null object's coordinates.
FYI this is how they do it in NASCAR, except with a live video processor instead of AE.

Tripp Woelfel
July 1st, 2008, 05:54 AM
Edward... I'm going to have to read up on null objects as they are one of many black holes in my knowledge of AE.

Kinda figured that's the way NASCAR broadcasters did it. All done in real time tied to the in-car GPS transponder. It's interesting that even at this relatively grassroots racing level, this small but storied track in central Maine is using transponders too.

Edward Carlson
July 1st, 2008, 08:33 AM
I learned about null objects from VideoCopilot.net. He is always using them to link motion parameters and such.

Cole McDonald
July 1st, 2008, 10:19 AM
I'd also recommend videocopilot's tutorials... godsend! You could probably even ask if he could cover that particular effect :)

Tripp Woelfel
July 1st, 2008, 06:03 PM
Brilliant! I just checked it out and I might not see daylight until the weekend there's so much here.

Thanks!

Giroud Francois
July 2nd, 2008, 12:16 AM
i would do that in flash.
you draw the balloon as a vector thing and you just need to keyframe the position.
when done, you just transform the SWF to AVI , color key the backround to make it transparent.
if you are good at programming in to flash, you can even design a general application that you can feed with coordinates (position x, y and frame).

Tripp Woelfel
July 2nd, 2008, 07:35 PM
Giroud... Interesting concept. I know about as much about Flash as much as I know mapping the human genome. The idea of feeding the x/y coordinates could simplify thing for repetitive use.

More to learn. Now if wonder if I'll live long enough.

Alex Sprinkle
July 8th, 2008, 09:40 PM
I agree with Edward. Just Null the End of it. IT's a lot easier than it sounds.

Jeff Koenig
August 13th, 2008, 02:29 AM
I know jack-all about AE, but I do know this... the "pointy part" of a balloon is called a "tail". ;)

How'd everything turn out?

Tripp Woelfel
September 6th, 2008, 06:05 PM
I didn't have time to do anything with this beyond some research. It takes enough time to get the balloons right for car and position. Gave up on the tails. I just float them over the car. It ends up being apparent enough as to which car its referring to. Doesn't seem to be a problem with up to three cars at once because I can hang them right over each car.

I have filed the "pointing the tail" concept in my memory because I'm sure I'll need that for something else in the future.