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rinny8
here's a load of questions
on Nov 11, 2005 at 10:22:56 pm


1. How do you make an effect appear behind an object or person? For example I want an explosion between two people, one near the camera and one behind them away. Is there any way to put the front person in front of the explosion without creating a big box around and them? Also how would you make it so that they still block the effect even while moving?

2. Is there any way to make the effect move with the camera? like say I want an explosion and to have the ground shake. How can I make the explosion shake with the camera?

3. Also is there any way to make an effect grow from small to large or large to small without changing the way it looks? When I change the size, it looks different than when it was at it's normal size.


Whew....thanks. As you can tell I'm like a total noob at this ^ ^


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Elvis Deane
Re: here's a load of questions
on Nov 12, 2005 at 2:36:50 am

1- There's a couple of ways to do this. You can use Blocker objects to trace around your person, which will hide any particles behind it.

If Blockers don't work for you, you'll need your background footage to have some sort of transparency information. If you're bringing in footage from an animation program, then that would be an alpha channel. With live actors, you either need to create a mask in a compositing program by tracing the outline of the actor, or shoot them against a greenscreen, pull the key, and then import the resulting footage with an alpha channel into particleIllusion.

Have a look at the section on Layers and Transparency in tutorial 4 of the Help file. That covers how you can pull a quick key in pI.

2- Offset does this. Once you place an emitter on the stage, select Offset for the layer you placed the emitter on in the library window, and then pick a point in your background video to use as your reference, then animate it so that the green offset cross matches up with that point throughout the video. There's a pretty good description of this in the Help file, as well as in this old post.

3- Try adjusting the Zoom graph rather than the size. Size controls how large each particle is, while Zoom controls the overall emitter.

--
Elvis Deane!
The particleIllusion FAQ
particleIllusion Resources and tutorial CD
Astounding Adventures


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rinny8
Re: here's a load of questions
on Nov 12, 2005 at 2:47:23 am

Thanks a bunch. If I use blockers, do I have to retrace the person or thing with them every frame when they move? That could get kinda annoying, if only I had one of those other programs...o well. Again thanks a lot ^ ^


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Elvis Deane
Re: here's a load of questions
on Nov 12, 2005 at 2:52:35 am

Yeah, you have to trace frame by frame. I generally position the points on one frame, movie 5 frames ahead, position them again, and so on. Then if that motion isn't smooth enough, start filling in the in between frames.

Also, breaking the body down into smaller shapes (one blocker for the arm, one for the head, one for the body, etc) makes everything a lot easier to manage.

Blockers also can only be straight lines, so that can be a bit limiting and have you end up with a lot of points. There's a freeware program called Wax that allows you to create masks with curves. I really can't vouch for how good it is (only tried it a few times), but it might be worth looking into if Blockers aren't working out for you.

--
Elvis Deane!
The particleIllusion FAQ
particleIllusion Resources and tutorial CD
Astounding Adventures


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rinny8
Re: here's a load of questions
on Nov 12, 2005 at 3:15:07 am

lol thanks!


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