Cracking Concrete

[Brian Lynn]

I’ve faked something like this, but not with effects really. Mostly phsical sets, two shots, one with no damage, one with. Shoot everything twice with both sets, as accurate to eachother as you can. Then I used masks to reveal the damage areas in a spreading pattern from the middle.

We filmed a fake fight where two “super heros” are throwing each other around in an alley. One smashes the other into a wall. We built the wall out of cinder blocks and painted it. Then we filmed our action sequence against the wall, one guy slamming the other with no damage. Then we took a sledge hammer, and some hammer/chisel combos and created a human outline of damage. Then we re-filmed the action sequence, timing it as close as we could to the original shooting. For the dust “poofs” we taped open sandwich bags full of baby powder to the inside of the wall, and had a couple straws filled. Subject hits the wall, the (gentle) force causes the baby powder to poof out of the bags creating dust around the victim, and the straws were used to create some more intense dust flying out from the wall in specific places. Comedy moment when one friend tried to blow powder for us, and inhaled with the straw in his mouth!

Using some creative masking I was able to reveal the damage as our subject hit the wall, appearing as if his impact had caused the damage. The fast cut nature of the action scene made it easy to piece together something fairly believeable. It might not pass broadcast standards, but then again, I had $0 for budget, the blocks were salvage from a building project, the paint was left over from when my mother had her house repainted, and it was just friends and I for the crew. And baby powder is cheap =)

It worked pretty well, went together fast, and I think it was a lot easier than trying to use digital effects or create a collapsable section of ground that damages as you like when your subject hits it. We tried “real time” damage, and after being tossed into a wall built to collapse, and almost knocking myself out in the process, we decided on a much more controlled method for our actors. I could care less if I get hurt, but talent is a whole different story!

Sorry for the long reply…
Brian

[Chris Leatherwood]

well that sounds pretty cool but as far as doing it with other effects already in place I’m not too sure how it would work. Plus I can’t go around chisling up the street in front of my house. The way you did yours sounds much the simplest way for your situation though. Very ingenious!! Thanks for your post and time.

[Brian Lynn]

Other effects already in place? Such as?

I agree, don’t tear up the street in front of your house… can’t advocate or support tearing up any public street… But you might be able to find a patch of bad street someplace that has the crack pattern in it you need. Try abandon building parking lots, old gas stations… I know a dead end near my house with no houses on it that would work well, and has a good sized depression/collapsed section where a heavy truck parked too long and damaged the road. Since you can’t control the shot as much as I could without building some serious sets, you might get away with some close ups… Just an idea…

Is your scene already shot and now you need to add the collapse in? Or are you planning the shot, fishing for an idea before you start?

You could try the Shatter effect… It can do a fairly good job of making walls and the like crack apart, completely blow holes in them if you like. You might be able to tweak the effect subtle enough to create the cracks and collapse you are looking for, but if your subject is already in the scene I don’t think that will work.

So many scenes in movies are closeups of one thing, a CGI shot of the landing, or sets and live action like I did, all mixed together and cut in ways that you don’t realize that you’ve gone from fake to real and back again. In a full studio production this would likely be a CGI patch of asphalt stiched into the scene, the collapse and the cracks all drawn. Talent would be filmed on a green screen patch on the floor, camera motion tracked, and the screen replaced with the CGI footage. Done right it can be fairly easy, though time consuming, and expensive.

Brian

[Chris Leatherwood]

yeah it’s just me trying to think about how to do it. I had intended for tthe person to be flying or perhaps have the cracking occur as the result of a spell. Your idea about the green screen and the shatter effect might be able to be melded and produce quite a nice looking effect.

[Nick Tregenza]

It’s always a good idea filming as much pratically as you can – but I am well aware of the scene you mean, especially as I just watched that movie again (for the sixth time?) earlier this week! 🙂

Without having AE open at the moment (and without dabbling with 3D apps like 3ds max where it would work well but take time to set up), you might try painting the crack pattern in Photoshop as an alpha channel and using it as a displacement map, again using animated masks to reveal the effect.

If the camera is moving – but panning only, or hand held in place – you could then track this effect to the shot quite nicely and easily…(otherwise yer getting into 3D work again…)

Just a thought! Have a look into the superb displacement mapping tutorials on here, by Aharon Rabinowitz – that should give you everything you need to pull this effect off quickly and easily.

If you want to dabble with partciles afterwards (Particular if you have it), you could create some simple dust clouds as he lands…good luck!!

Regards,
Nick