Projecting images onto a sphere

[Kyle Shapiro]

Hi I was asked by a client to reproduce something very similar to the included video and was wondering how I would do it. I think the background is rear projection where as the sphere is just fisheye footage projected onto the sphere, but that seems to easy. Have any of you done anything like this before? Thanks in advance!

 

Edited November 3, 2011 by Kyle Shapiro

[Chris Millar]

Not enough information from the video.

 

How big is that sphere ? What is happening around the sides ?

 

Your idea sounds possible, but you're going to have these following issues:

 

~The resolution around the edges will be terrible

~You're going to have either spill on to the BG and/or uneven coverage on the sphere

~To get it really bright you're going to have to have the projector close, which means less coverage on of the sphere and also more relative fall off around the curves

~Rather than use a fish eye I'd do the squishing in post, at least if you can code that yourself you'd have complete control over the reverse distortion (a fish eye will have it's own idiosyncrasies)

 

Major issue really is coverage ...

 

Solution which solves all of those things is multiple projectors blending into each other, each placed around the circumference of a greater diameter circle around the sphere - potentially inside it if it's large enough...

 

oooor, make it out of LED's - I'd be surprised if one of the chinese outfits making these in the millions hasn't made a spherical system - you can see some maybe seams on it when it goes open white (?) - with a low enough res camera low res LEDs will look solid.

[Phil Rhodes]

I think, but I'm not sure, you can do this by bouncing a rectilinear image off a chromed sphere. Optical performance will depend on the quality of the sphere and there will always be a blind spot, of course, where the reflected image strikes the projector itself.

[Chris Millar]

I think, but I'm not sure, you can do this by bouncing a rectilinear image off a chromed sphere. Optical performance will depend on the quality of the sphere and there will always be a blind spot, of course, where the reflected image strikes the projector itself.

 

You mean casting virtual images ? (I thought that was a concave mirror type trick ?)

 

...always keen to learn about these things