Camera to simulate 2 (or more projectors)

[Steve_Green]

Hi,

this is going to seem like an odd request.

I've recently been doing some work for an events company which provide projection mapping onto buildings.

Sometimes this is achieved using multiple projectors set apart which overlap, especially on long buildings.


Ideally I'd render the view from the where each projector is, so the perspective matches - but then there is a problem where the overlap happens, especially if objects move over that join.

Longer focal lengths minimise the problem, but then things tend to look flatter - I've also tried building the model distorted to compensate, but that can be an issue if the building has to animate/disassemble in the animation as you see the tricks used.

I've not found a solution and mapping companies don't tend to talk to each other. I did wonder if there was a way of doing something with the ability to distort the lens in VRay, but it's simulating something very unnatural (multiple perspectives from a single camera)

Anyway, I thought I'd throw this out there to see if anyone had any ideas, but I acknowledge it's a pretty niche question...

Thanks,

Steve

[wxyz]

Can you emulate the projector lens distortion by reflecting the images off a distorted mirror?

[Dave_Wortley]

Maybe talk to these guys? http://seeper.com/

[Steve_Green]

Unfortunately they're competitors to the company I'm doing work for - I don't think people share their info in the mapping industry...

[ecraft]

You try watching the making of this AREA customer story. It is based around Maya, but may give you some incite on how other companies are approaching the issue(s).

-Eric

[Steve_Green]

Thanks, I'd seen it before but I forgot about the behind the scenes video - I'll see if there's anything revealing there.

Cheers

[flino2004]

you have to render from the point of view not from where the projector is located....after you have the animation you distort it to match the projector location.
mapping projection is an effect from a very specific point of view to get it right.....no always you can have the projector where you want.

My partner & I made a projection in Chicago, it was much simpler because it was only a plane...If I remember well, we used 2 (30K lumens each) projectors.

http://vimeo.com/13381869

[flino2004]

I found a couple images, one from the camera and the other one from the projectors



When you have two planes and two projectors far apart it's a lot more complicated, because you have to create an animation from the point of view, and another animation from the camera projecting the animation from POV..
Imaging like you are projecting the animation from the POV and you have a camera recording from the projector.
Nobody wants to talk about it because it's not a book where you can get the info, and pretty much you have to figure it out yourself.....I don't have expirience in two planes or more but I have the concept in my head.

a reference

http://vvvv.org/documentation/how-to...on-3d-geometry

[Steve_Green]

Hi,

Yeah planes aren't really a problem - it's always a bit of headscratcher getting a sweet spot on buildings that aren't flat.

The mapping is tweaked on site using Wings, but it's still something I'm getting my head around.

Thanks

Steve

[flino2004]

post the building and a scheme showing the POV and potential places for the projectors just to think about...maybe somebody here can help you to figure it out the issues.
in real life if you find the sweet spot maybe you won't be able to use it bacause is in another building with different owners, they don't want to see your projection like happen to us in Chicago(on top of that one of the residents was a political personality moving his/her influences Chicago mafia style).

[Steve_Green]

Will do.

Yeah, it's a pain dealing with positioning the projectors - we had a possible location that we got turned down for - the owner of the building was fine but the council nixed it, the same council that allowed the Ralph Lauren shoot which was a much bigger event... money talks...