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Activity Forums Apple Motion How to emit from certain objects using video as source?

  • How to emit from certain objects using video as source?

    Posted by Mark Bowen on October 21, 2020 at 7:27 pm

    Hi there,

    I have a video with simple rectangular (slightly curved curners) falling from top to bottom in different places.

    I’d like to create a particle emitter system which emits particles from these shapes as they’re falling.

    I have made a very very simple and crude particle emitter but have no idea of how to make the particles emit from the shapes in the video.

    The shapes in the video are all one single colour on a black background. Not sure if that helps or not though?

    If anyone could help with this then I’d be very grateful. I’m very very new to Motion and not really sure if it can actually do what I’m looking for or not so any help would be greatly received.

    Many thanks in advance.

    Best wishes,


    Winston A. cely replied 3 years, 7 months ago 3 Members · 6 Replies
  • 6 Replies
  • Robin S. kurz

    October 22, 2020 at 8:36 pm

    You can set the Emitter shape to “Geometry” and then define your shape as the Shape Source. Then whatever you have defined as your particle CELL will only emit from the boundaries of that shape.

    – RK

  • Mark Bowen

    October 22, 2020 at 11:03 pm

    When you say shape though these are shapes that are in a video so not each one is separate they’re literally ‘baked’ into the video as it were. Basically a bit like if you were to imagine very large rain drops coming down in a video except it’s video and not separate shapes.

    Will that work then? Will have to give that a go and see.



  • Mark Bowen

    October 23, 2020 at 7:35 am


    I tried selecting Geometry however I can’t drag the movie clip that has the ‘shapes’ on to it so that’s not working unfortunately.

    I then tried ‘Image’ from that same setting as I had read that if you have an image with an alpha channel then they will emit from that and it did allow me to drag the movie in (I’ve made it an alpha channel movie so the shapes are falling down the movie on their own with a transparent background) but that doesn’t do anything. The particles aren’t even getting emitted unfortunately 🙁

    I’m pretty stumped at this point. I’m going to try attaching part of the transparent video that I’m using in the hopes that maybe someone can see what I’m trying to achieve and can perhaps instruct me of how to get what I need here. Hoping this is possible as I don’t really want to have to fork out buying something like After Effects and Particular Trapcode.

    Many thanks to everyone for all their help with this as it’s really very much appreciated.

    Best wishes,


  • Mark Bowen

    October 23, 2020 at 7:37 am

    Basically I’d like to initially have say particles that look like an upward flowing waterfall coming out of each of those shapes as they fall if that’s possible.

    Next I’d like to be able to have the upward flowing waterfall only start when the notes have fallen past a certain vertical position but not sure if the first part is even possible yet 🙁

    Thanks again for any help with this.

    Best wishes,


  • Mark Bowen

    October 23, 2020 at 8:13 am

    As a matter of fact if I try adding a very simple shape to the project on a new layer, say just a rectangle and I use that as the shape source for ‘Geometry’ for the particle system then again there is literally no difference at all! 🙁

    From looking at the documentation on the Apple site the particles are meant to emit from that shape but they don’t, they literally just emit from the exact same place on the stage where I initially made my particle system 🙁

    Really not sure what I’m doing wrong now though?

    Best wishes,


    P.S. Have now attached a very simple Apple Motion project to this post to show what’s happening with a really simple shape as the emitter Shape Source when set to Geometry.

    I think perhaps I’m completely misunderstanding what that’s for though possibly?

    Even if that did work though I’m not sure how it would help me out with making the particles track the ‘shapes’ that are in the video file attached a few posts above though?

  • Winston A. cely

    October 27, 2020 at 5:19 pm

    I’m not sure if this is what you’re looking for or not. I kinda think it might not be upon re-reading your posts, but I’m gonna throw it down here just in case:

    So I think you need an image sequence that you playback as a single movie.

    First, cull together all the images you need. Make sure that they are in a video-friendly format (like png), scaled to roughly the same size, and that they have an alpha channel.

    Next, make sure that they all follow the same naming pattern. This is per Apple’s site for image sequences for Motion:

    Important: Any imported image sequence must contain three or more digits of padding—for example, “imagename.0001.tif.”

    So you could do, “emoji.0001.png” “emoji.0002.png” etc.

    Then, make your Motion project and import your image sequence. Again, from Apple’s site:

    1. In Motion, do any of the following:

      • Choose File > Import (or press Command-I).

      • In the toolbar, click the Import button.

      • Control-click an empty area of the Layers list or canvas (in the black area outside the project), then choose Import from the shortcut menu.

    2. In the dialog that appears, navigate to the image sequence, then select an image in the sequence.

    3. Select the Image Sequence checkbox.

      Note: If the Image Sequence checkbox does not appear, click Options in the lower portion of the dialog.

    4. Click Import.

      Motion uses each image in the sequence as a frame in a movie clip.

    Now, that you have the image sequence imported, you can use it as your source for your emitter. The key here is that you want the emitter to choose a random frame from the source image sequence.

    This should enable you to use one emitter that emits different images.

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