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rockhoppermedia 11-07-2011 01:19 PM

Moving planar matte help needed!
 
I am working on a film project, I have a camera locked off on the wing of the aircraft pointing it back on itself. Now here comes the hard part, the ground in the rear of the shot requires a WW1 battlefield overlayed. IE motion matte painting, I have masked off the aircraft. I need to fill in the hole, or put together a moving planar tracked matte. I only have mocha ae, and after effects.

Need some help with this, just to work out how to match the ground which is going up and down and twisting,

anyone done this before, not looking for a quick fix just want to get on with it. The footage is ten seconds long!

nickmarshallvfx 11-07-2011 02:11 PM

Hi Rich,
Sounds like it could be a tough one, but depends on how clear your ground plane is to get a track from and how much parallax there is around the area that you need to add the matte painting. The first thing i would go to is mocha for a track, its a very powerful tracker, but id be tempted to go 3d for a shot like this if at all possible, either in a 3d package or all in Nuke. Are you able to show the plate or is this under NDA?

N

rockhoppermedia 11-07-2011 02:39 PM

Nick

I am under NDA at the moment, which sucks, the background is twisting and the parallax is all over the place, they did say I have three months with this. I have Mocha but never used it for anything major than corner pinning. I am thinking of creating a 3d model of the ground and using that. However the nice cameraman neglected to place tracking markers in Z space I have x y data and having to use off-screen tracking.

The film is an old film shot in 198# however they are thinking of doing it redux style. Which is when I got the call. So tracking markers were never used till later that decade. As for hdri got round that. I have cut and pasted a HDRI sphere from elements from the scene which is very diffuse.

Done a rough garbage matte so far, the damn plane is filling the whole frame. So it looks like a old fashioned hand by hand frame by frame track is needed.

this track has to be spot on as I am comping by hand smoke from the ground up using cards.

The ground itself as a matte is very very easy to do, as there is motion blur there is no need to go for pixel perfect, can use a impressionistic ellenshaw style. However it will still be HD quality.

I know ILM used a in house technique for mission impossible 2 doing something similar. So I know it can be done.

Alex Jenyon 11-07-2011 09:21 PM

If the plane is locked off, and only the background is moving, you theoretically don't need a perfect track - you could replace the whole thing with a 3D environment, and roughly match the movement.

Since you can't show us the plate it's a bit of an academic discussion - you are either going to be able to track the plate with the tools you have, or you can't, and your workflow will come from that.

Best of luck - enjoy!

AJ

Pavel Cucka 11-08-2011 02:08 AM

Exactly my thoughts, Alex!

If the plate background is crap, then don't retouch it, but replace it!
Since the camera is locked off on the wing, it shouldn't be too hard to get a matte of the plane, since it won't really be moving.
All you need to do is to create a good 3D/2.5D matte painting of the WWI environment and either track or recreate the camera movement. You can alter it quite a bit too.

Sound like a fun shot :-)

rockhoppermedia 11-08-2011 03:04 AM

Alex, Nick, Pavel,

Thanks now I know exactly how to handle it, going to do a 3d model using the textures from the original plate,

The original shot is a cool shot on its own but it can be improved.

Thanks for the help, 3d model is the way ahead, plus the benefit of using cam mapping using selected parts of the shot.

10 secs of hell, this is going to be brilliant.

Rich

rockhoppermedia 11-12-2011 03:32 PM

Problem solved !!!!


there are two ways to solve this problem, if you have a clean background plate, you can use

Autodesk Photofly, the results can be a little ropey. its designed for a object at a fixed nodal point.

The second similarish program is to use Arcsoft panorama maker 5. My footage was not suitable to use. However test footage worked out fine.

The second way is the hard way and if you have ever worked in animation you will have the patience for it. You need to render out the frames in jpeg/tiff/png format then hand stitch them together, you need to remember it will not be in a straight line, the image will build up as a curve.

Once done apply a stroke to all the layer images this will work as your place holder. The idea is to set the composition up in after effects, matching the orignal frame rate and screen size. Then set your image on the last frame, using auto tween/keyframe move it along to the first frame and move it into position. Now is the hard part, you need to hand animate along the timefram the position.

Tip which I did not do and that is to put a frame number into the image place holder, the idea is to move to keyframe 034, and then move the place holder matte to placeholder 034.

you will need to adjust your bezier curves in your timeline. to smooth out the motion.

Once done, you can go back into the psd, turn off your frame numbers and stroke, and paint in your matte over the background shot.

Once done all you need to do is copy and paste the position data of the place holder matte and transfer that to your finished matte.

You should then have a matched background to the original moving shot.

the reason I did it this way is because in the middle of frame cover 65% of the image was an aircraft.

Love to show the results. But with lots of patience and time you can do this.


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