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Forums Adobe After Effects Draw line on map – follow a “ball”

  • Draw line on map – follow a “ball”

  • Eric Holzapfel

    September 26, 2011 at 3:33 pm

    Hello Members,
    First, thanks to creative cow forums for the outstanding level
    of information and help in the forums I frequent!

    I have searched around, but never quite could figure out how to do
    this: a “ball” or circle moves over a map from city A to city B to C, etc. As my little ball moves a nice ‘line’ traces on the map (a brush stroke?).

    I have seen tutorials on writing a signature, but those just reveal what is already underneath (Ahron Stern, signature for one, and another from Layers Magazine). What is a good way to draw a line that just follows the ball as it moves over the map?

    I have currently, four layers. At the bottom is the map, next a black solid with opacity set at about 45 or 50 percent. the layer on top of the solid is a bunch of dots and city names, the dots and text are over matching city name on the map. The top most layer is the object (a small circle) that I want to move from city to city, with a line tracing the path of the ball.

    I do not want to “reveal” the road under the map, just have a line that moves along the path from city to city.

    I am open to any and all suggestions.

    Thank you Creative Cow, and members,


  • Matthew Keane

    September 26, 2011 at 3:51 pm

    One way to do this, if you have the plug-in, is with Trapcode Particular. Animate a Null between the points on your map, and then use that as the emitter point for Particular. By setting the particle velocity to zero, this will leave a trail of particle along the path, and you can use the various particle options (size over life, opacity over life) to get the style of trail you want. You can even animate the starting opacity of the particles to make a dotted line if you want.


  • Kevin Camp

    September 26, 2011 at 4:01 pm

    you might try the write-on effect. you may be able to simply copy/paste the dot layer’s position keyframes on the brush center property, but i would use try using expression to to link the brush center to the dot position…

    simply enable expressions for the brush center property (select it then choose animation>add expression). then use the expression pickwhip (looks like the parenting pickwhip but is to the right of the property that has the expression), and drag that to the position property of the dot layer. that will link them together, so as the dot moves the brush center will track it.

    then just tweak the other brush properties to get the line that you need.

    Kevin Camp
    Senior Designer

  • Eric Holzapfel

    September 27, 2011 at 1:41 am

    Hello Guys,

    Thanks for the help. Unfortunately I do not have the Trapcode plug in.
    I will try the suggestion about using an expression, etc.



    Final Cut Pro, Adobe After Effects, Photoshop

  • Eric Holzapfel

    September 28, 2011 at 2:22 am

    Hello Kevin,

    When you say “brush center” do you mean position (x and y) or anchor point?
    I do not see a property called “center’ for a brush.

    Thanks for this help.


    Final Cut Pro, Adobe After Effects, Photoshop

  • Kevin Camp

    September 28, 2011 at 10:04 pm

    sorry eric,

    you’ve probably figured it out by now, but it’s called ‘brush position’ within the write-on effect controls.

    Kevin Camp
    Senior Designer

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