questions about bluescreen, among other things

[Jayk2k]

A1) Use a stick with a tracking mark on it where you want your actor to be. Then you can track this and apply the same motion to the actor shot on green/blue. If done correctly, the actor will cover up the mark, and you won't even know it's there.

There may be issues if you want your actor to be moving around on his own. In that case, still shoot the stick, but make it small enough to be easily removed, and yet large enough to track.

Then shoot the bluescreen with a locked off camera, and let the actor do his thing. Then when you add the motion of the background to the actor, it should look ok. (this is why most people end up using motion control rigs... )

A2) Z depth is handled in most compositing apps internally, and all you need to do (in fusion anyways) is add a depth blur, and it will blur the image based on the z information.

In photoshop, you should be able to use the z-depth as a mask of sorts for a blur, but as far as i know, photoshop doesn't support z-depth.

Again though, this doesn't always produce great results. its a 2d cheat of a 3d effect. the problem lies in that the 2d image has no information as to what is behind other objects, and thus when bluring, can only blur with what it does have. This generally causes ugly artifacts on large blur amounts. It might be subtle enough in a small amount of blur that you don't notice.

A3) Welcome to the ART behind compositing. There are ways to deal with this, but it mostly comes down to excperience. you need to know how many points are needed to track the shot, but not too many that you're painting out things all day.

You can try to set up the ponts to a specific colour, and key them out later, or track each point (that's what they are there for) and attach a clone stroke to the track data. This can be the simplest of techniques, but may not always work.

Last ditch effort is to paint each frame by frame, but as you say, this can lead to boiling of the strokes. This is just a lot of trial and error as you learn how to deal with it. For the most part, consistency is key.

[torbjorn]

Hey, thanks for the reply jayk2k, I guess i have to read your reply once more to fully understand what you wrote :) Motioncontrol rig? Is a mo-rig, a thing that records movements, OR, is it just a rig that makes the camera to follow a certain path over time, so that you can add a background with the same movement as the "bluescreen guy"...?

I'll keep reading about this, it's interesting...but it's hard to know what you're actually suppose to look for (on google for example)


cheers...I'll be back with more questions as the pop up ;)

[dg]

Hi,

Motion control can record the movement of the camera and then replicate that movement precisely, you can also export your camera movement from a 3D app to be executed by the real camera in a real enviroment and vice versa.

As for z-depth in PS, you can render a z-depth pass in a common format like tga, tiff (some that Photoshop can read) and the use a plugin to create the dof blur called Lens Care (http://www.frischluft.com/), or if you have Photoshop CS you just need to use the lens blur filter.


I hope this helps.


Cheers,
dg

[torbjorn]

Hey thanks, the motion rif explenation opened up my yeyes a bit, and gave me a few ideas...Anyone knows about the cost to buy a motion rig or what's the price to rent one?

Thanks pals / t

[beaker]

Motion controll rigs are really expensive and a pain in the ass to program. They can cost anywhere from 10,000 a day to 100,000 a day to rent, plus you have to pay for an operator/programmer for it.

[altruizine]

yeah, a motion control rig is gonna cost you an arm and leg. Your best bet may be to try a 2.5D solution. If you can infact track your actor based on marks you put up, you could perhaps try to build the background you want based on photos and some creative mapping, then importing your track data to 3dmax and doing the move there. It all depends how much your camera moves, but if you're on a bluescreen you're probably pretty limited. So you may have a shot at that working.

I recently did some spots that were storyboarded to have a camera track around the talent on greenscreen. We did not have the money for motion control nor do we own tracking software. We ended up putting the talent on a turntable and I matched the rotation by hand in 3d. worked out great and had a nice high value look to it.

Just a note that many times the solution takes some creative thought. A solution like Motion Control is rarely the only option and also rarely a panacea, they are very difficult to use at times unless you have a good deal of experience working with one. It would be great for a cheap motion rig to come about some day, but I just don't see that happening since they need to be heavy, fast, stable and VERY accurate... and that costs.

stick with tracking your data if you've got a tracker. think about your solution a bit more, read a bunch of fx mags and come up with a creative solution.

-JF

[torbjorn]

Thanks guys, I just talked to Chris Maris (www.chrismaris.com) about motion control rigs and...well, as you say, they are costy :)

Ok, thanks, now i know a tad bit more about this...i'll keep diggin though...

cheers / T

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