Wesley's Weekly HOW TO: Impact Strikes

POSTED BY Wesley Scoggins, 30 January 2008

Many questions have been asked how to make it look like bullets are hitting the ground and walls, and while there are a lot of ways to do this, there aren't a ton of options if you unfortunately lack a budget, and a pyrotechnian to rig up hundreds of little charges for you in a fake wall.

Well thanks to digital technology, we can now composite self-created effects into our own footage, and I'm going to show you how.

For this you'll need:

- A black foam board.

- Flour or Powdered Sugar.

-A can of compressed air.

Firstly, get your foam board, and make a shallow cut in about the middle of the board.

So it can easily be folded into roughly a 90 degree angle, like so.

Then fill the angle with hot glue.

So it stays at a 90 degree angle like a giant laptop.

Now poke some holes in it; use something thin, like a tiny screw driver, or an ice pick.

The horizonal holes are for ground strikes, and the verticle holes are for wall strikes. Next, get the straw that came with your compressed air, or a tiny coffee straw.

And push it tip first, into your flour or powdered sugar, stuffing it full of the powder. The push the packed end of the straw into the foamboard.

Just push your compressed air into the end of the straw and give it a quick spray, and BAM!

You get a nice big smokey explosion with no fire or pyrotechnics. You could easily get multiple straws, and do multiple while you are filming. For a ground explosion, just get a spoonful of your powder medium, and stack it up on one of the horizonal holes.

To allow my hands to get under the panel...

I balanced the board on a garbage can, so I can reach underneath it, you could use anything that could hold it up but let you reach the bottom. But after I could get under it, I stuck my straw in and gave it another quick spray of air, making it spray everywhere again.

And there you go. Just film these going off, and import them into your editing program. Using Steve's Greenscreen tutorial, and Justin's motion tracking tutorial, you can take the mini-explosions you create using powder and compressed air, and key out the black, color correct your white particles to whatever looks right for your footage, then just motion track the explosion footage onto your footage using motion tracking.

You can used pieces of tape on the wall, or even pushpins to act as the motion tracking points (push-pins would be ideal as they could be rather easily hidden by the footage covering them). Also, for this, it might be a good idea to paint a patch of color surrounding the hole as the same color as the wall or ground that the impact point is going to be coming from, so it can blend in a little better.

For bomb craters and stuff you might want to add some pieces of foam, or other bigger debris to the area around the hole on the foamboard, to make the explosion look like it's throwing heavier stuff into the air.

But there you go, custom impact and bullet strikes for when you can't find exactly what you need on detonation films.

-Wes