Some time ago, I wrote an article about how to make a mustache explode. It was an effect I used in the Bucket Dan iOS video game teaser. In this article, I'd like to expand on it and make it a bit more practical. I'm going to take a person shot on green screen, and make her turn to dust, using Motion 5. This same trick will work in Motion 4, also. This can be a tricky effect to achieve. The better lit and less work your green screen shot is, the better your results for this technique will be. And since this requires generating many thousands of particles, you may see some sluggish system performance, depending on what GPU you're running. So let me show you the basic technique, and you can refine it on your own from there.
Launch Motion 5, from the Project Browser I'll select Motion Project, and the Broadcast 720 preset at 24fps, and a duration of 5 seconds. In the project, the Render menu at the top right of the Canvas, I'll set Resolution to Half, Quality to Draft, and turn off everything below that, Shadows, Reflections, etc. This will help with system performance since we're going to create a bucket load of particles. Then I'll import a green screen shot of my buddy Paddy from Ireland.
With my clip selected, I'll hit the End key (Fn-right arrow on a Mac laptop) to send my playhead to the end of my project, and hit O to end my clip there. The Home key take my playhead back to the beginning of my project. In my clip he starts with his head down, so I'll slip this by holding the Option key while clicking and dragging directly on the clip in the Timeline.
The first thing we always do with green screen shots is crop out the garbage we don't need to deal with. My clip of Paddy is highlighted, I'll F1 to the Property controls, and down for the Crop section, I'll Show it, click the blue enable button (left of the word Crop), and adjust the left, right, and top to focus in only on Paddy, and eliminate all the other badly lit sections of the screen. Then I'll Command-2 to the Library, go to the Filters, to the Keying collection, and apply the Keyer filter. It works great by default on good shots, but mine wasn't lit all that well. To clean it up, I'll click the color selection tool (red square) and select the top right to clean up my badly lit green screen. I'll do it again and select a section of my lower left to clean up a bit more I can see isn't quite keying right away. For more information on using the Keyer filter, see Michael Wohl's video tutorial Motion 5 - 104, Effects, Particles and Replicators here at macProVideo.com.
I'll hit C for my circle drawing tool and draw a small circle. With this new shape layer selected, I'll go to the Object menu and select Make Particles. The keyboard shortcut is E. Then F4 with the Emitter layer selected for its controls. Change Shape to Image, Arrangement to Random Fill, and drag my keyed clip layer into the Image Source well. The Circle layer's visibility is automatically disabled, which we want. Then set Shape to Image, Arrangement to Random Fill, and drag my keyed clip into the Image Source well. With my playhead at 2 seconds, the Emitter layer selected, hit I to move its In point here.
I'll set the following settings: Emission angle = 360, Birth Rate = 0, Initial Number = 20,000, Life = 10, Speed = 500, Speed Randomness = 100, Scale = 40, Scale Randomness = 10, Color Mode = Take Image Color. So only 5000 set particles move in all directions, variable speeds averaging 100 pixels per second. See Figure 4.
You can start with a small number of particles, then increase the number of particles later, to get better system performance while you work initially. All of these settings can vary depending on your original clip and the exact effect you want to go for.
Next I'll make them fall to the ground. I can use Command-2 to quickly jump to the Library. Then in Behaviors, in Simulations collection, I'll apply the Gravity behavior to my Replicator layer and set Acceleration to 10,000. That is how strong gravity pulls the particles down to the ground.
Finally I'm going to select the Emitter layer, hit Shift-I to get to its In Point. Use the right arrow key to take the playhead 5 frames to the right. Select the keyed clip layer, hit O to set its end point there. In Behaviors, Basic, apply the Fade In/Fade Out, with Fade In set to 0 and Fade Out set to 8.
If you want to try for a bit cleaner look, place your keyed clip, and any background you may add into their own layer, and place this layer as the lowest level layer. Create an other layer for your particle emitter and source shape, place this as the top most layer. Then with this top layer selected, F4 to the Layer Inspector. Turn on Fixed Resolution, and set the width and height to only be as large or small as necessary to fit your dust effect inside of.
Be cautious with your source clip, make sure it isn't too large or complicated. And play around with the fade out time. I created an exaggerated fade out time here, just so you can see how the overlap works. Use a shorter fade out time.
Finally, if you are exporting to composite in another application, be sure to go to the Render menu, top right of the Canvas, and reset Resolution to Full and Quality to Best. Command-E to export and in the export window, set Export to ProRes 4444 in the Options section, and Color set to Color + Alpha, and the Premultiply Alpha check box checked in the Render section.
One last tip, if you want to play around with other Simulation behaviors with particle emitters, be aware that Gravity is the only really reliable one. Many of them don't behave as you'd expect. But feel free to experiment and see what you can come up with.
And there you have it, the very basic tools for turning peoplein to dust with Motion! Of course you'll tweak these, add to them, alter this technique in a variety of ways to suite your personal needs. But as you can see, any object can be turned to dust, or even just blown up (turn off the Gravity behavior). Hope you found something useful in this article, and it helps you to explore other amazing tricks that are easily done in Motion 5.