You are viewing an archive of the old fxhome.com forums. The community has since moved to hitfilm.com.

Explosion ground effect

Posted: Mon, 28th Sep 2009, 9:43pm

Post 1 of 5

smoores

Force: 400 | Joined: 6th Jul 2009 | Posts: 18

EffectsLab Pro User FXhome Movie Maker

Gold Member

Alright, so I'm working on a war film yea? i got the gun and blood effects down.got the explosion part pretty well, but how do I make it so the ground below the explosion changes? like a grenade/mine effect.
Posted: Mon, 28th Sep 2009, 10:42pm

Post 2 of 5

Axeman

Force: 17995 | Joined: 20th Jan 2002 | Posts: 6124

VisionLab User VideoWrap User PhotoKey 5 Pro User MuzzlePlug User PowerPlug User PhotoKey 3 Plug-in User FXhome Movie Maker FXpreset Maker MacOS User

SuperUser

Generally, this is done practically, on location, while filming. The simplest way: You dig a hole, put one end of a board in it, fill the hole back up with dirt, covering the board. As the actor runs up, he stops on the other end of the board, sending a cloud of dust into the air and resulting in the crater being exposed. Of course, remove the borad before filming shots of the actual crater. If you want to do it in post, keep in mind it will be more difficult and likely will not look as good. However, here's how its done:

1. Composite in a crater. Get an image of a crater, and composite it into the footage. This will likely require some decent compositing software, which EffectsLab isn't designed to be. This could be as simple as digging a hole and taking a photo of it. Then mask out everything other than the hole, so it can be positioned over your footage. I assume the crater resulting from an explosion is what you are asking about.

2. Use scorch marks instead of a crater. You can use grading filters or an image to darken and scorch the area where the explosion happened.
Posted: Tue, 29th Sep 2009, 2:37am

Post 3 of 5

smoores

Force: 400 | Joined: 6th Jul 2009 | Posts: 18

EffectsLab Pro User FXhome Movie Maker

Gold Member

Thanks yea that's pretty much what i mean. so like for scorch marks how do you apply grading to just one area? cause the scorching would seem like the simplest idea.
Posted: Tue, 29th Sep 2009, 3:01am

Post 4 of 5

Axeman

Force: 17995 | Joined: 20th Jan 2002 | Posts: 6124

VisionLab User VideoWrap User PhotoKey 5 Pro User MuzzlePlug User PowerPlug User PhotoKey 3 Plug-in User FXhome Movie Maker FXpreset Maker MacOS User

SuperUser

The easiest way is to apply a Grade Object, and then use a mask to isolate the grading filters you add to a specific area. Invert the mask to retain only the area inside of it.

The Meteor impact listed under Compositing on this page has an example of this technique in action. At the end of the video, the scorch marks left behind are created using grading filters. I'm pretty sure.
Posted: Sat, 3rd Oct 2009, 10:12pm

Post 5 of 5

smoores

Force: 400 | Joined: 6th Jul 2009 | Posts: 18

EffectsLab Pro User FXhome Movie Maker

Gold Member

Thanks for the help axeman. Here's my first test mine explosion if you want to check it out. http://www.youtube.com/watch?v=PJdIkHPTSwQ