Lining up geometry to footage in 3d package

[DoubleSupercool]

I am wondering about this as well. I have done some PFTrack stuff and usually I get pretty good results with ground planes, but I am getting into projection mapping now (projecting still photos onto low res geomety) and it is a bit of a bugger.

One thing to remember is that all real lenses have distortion while CG ones do not. Keeping this in mind you will realise that your CG scene will never exactly match your filmed one. Of course, there is software out there that will correct a lot of this distortion (inlcuding tracking software and Photoshop CS2 for still images)

[Shayder]

Yeah, I've been starting to do more and more of the projection mapping as well. The whole lense distortion thing to me is a mystery. How does one tell when there is distotion or is there always distortion. I thought it was only for stuff shot with a wide angle lense. If there is distortion is there a easy way to tell how much? I haven't used any distortion tools yet, are they tricky to use? Do any Cg packages have a distortion setting?

Wow, that's a lot of questions, I hope someone can answer some of them, Thanks!

[GallenWolf]

Hiya man. To see if your lens exhibits distortion, shoot a brick wall straight on, or vertcal objects. The distortion will be easier to see at those angles, and if there is its usually at the edges. For how to correct 'em, sorry mate no idea. I believe matchmoving tools like pftrack may have built-in correction tools but that's outta my league.

HThs!

Alvin

[Domo_Digital]

hmm tough question, I wonder though, you say you import the camera to Maya. I use Boujou to track, and when you import the camera it comes with track reference objects which in Boujous case are locators. WHen you look at all these locators you can imagine your scene there, and see where the ground is, or say it tracked a little pebble, you can tell in your footage where that pebble is in relation to the camera, and try placing your geometry accordingly. Of course I have no idea how other tracking software works, but it may be similar, I hope this helps :)

[boboroshi]

I thought PF track had a paarallax correction tool... i might be wrong. It used to be called Icarus before it was a commercial product - you might be able to find the free version online somewhere still (it was a UK university project).

Not sure if Maya Live will help you in this situation.

Whenever i get architectural shots, I always have a probelm (those guys LOVE to shoot with super-wide lenses). What I tend to do is correct the plate in shake or another tool and then work with the CG. COmp it together and restore the lense artifacts (if needed) in the compositing app.

[beaker]

Hiya man. To see if your lens exhibits distortion, shoot a brick wall straight on, or vertcal objects. The distortion will be easier to see at those angles, and if there is its usually at the edges. For how to correct 'em, sorry mate no idea.Similar to this, usually we shoot a grid on a piece of poster board. That way you can get exact registrations for unwarping your plate.

[NickJushchyshyn]

There are many ways to handle the distortion.

MatchMover pro comes with a utility that will remove distortion from the original plate based on it's matchmove findings. (It's a command-line utility though.) It also can export distortion correction data to Shake so it can be handled in the composite.

For camera projection/camera mapping, consider mapping textures from individual frames on to the geometry, instead of projecting the moving video which can tend to bring attention to subtle inconsistancies in the final solution.

In the end, the matchmove result is an approximation. It's typically not an absolutely precise result. Especially if you're working with lower res sources like DV or HDV.
Hope this helps a little.
Good luck.
Have fun.

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