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How to create explosion bloom around keyed objects
I have a 3 layer comp, (1) background plate (2) explosion (3) foreground actors.
How can I get the explosion light to bloom around on top of the actors as well as behind them? I remember somewhere in an Andrew Kramer tut he talked about this, but I dont remember the steps.
Thanks
Randy -
3 Replies
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I think he created an adjustment layer and added glow, then adjusted the settings. Its on his Serious Effects and Compositing DVD.
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Create an Adjustment Layer. Mask it along the edges where you want the bloom to occur. Add Glow BUT adjust radius, intensity and mode to taste.
A quick way to do this is to use Find Edges once you’ve keyed out the foreground. Then apply Auto Trace. Then simply adjust the resultant masks to cover the areas for the bloom.
Lastly, set the Adjustment Layer’s Blending Mode to Add.
Cheers
Roland Kahlenberg
https://www.broadcastGEMs.com – Adobe After Effects project files
https://www.myspace.com/rorkrgbspace -
I no longer use the Glow effect out of principal, so this technique might seem more involved but I think it produces better results:
1. Duplicate the explosion layer and the foreground layer, pre-comp these.
2. Make sure that the foreground layer is above the explosion layer in your pre-comp.
3. Set the foreground layer to the Silhouette Alpha blending mode and duplicate it again, set the duplicate to the Stencil Alpha blending mode.
4. Apply a Simple Matte Choker to the Silhouette Alpha layer, you may not need to use this effect but it will allow you to increase the amount of bloom on the foreground.
5. Apply a Box Blur to the Silhouette Alpha layer, iterations at least 3 and radius to taste.
6. Back in your final comp make sure that the pre-comp is above your foreground layer and set it to use whatever blending mode the explosion was set to.
Once you have the basic concept (create a matte for the explosion from the foreground, blur it some) you can create/adjust this effect in many different ways.
An alternative, for example, could use a duplicate of the foreground (again with a simple choker and box blur applied) as an alpha inverted track matte for the explosion layer, which you would put above the foreground.
I encourage you to come up with new ways of pulling mattes, and new effects to apply to come up with the look you’re after (a radial blur set to zoom can cast cool light rays for example).
Darby Edelen
Designer
Left Coast Digital
Santa Cruz, CA
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