3D Camera Lens pictures viewable in Rift?

Perhaps I'm being simplistic, but a camera with proper lens spacing does away with any problems of scale. I use a Fugi FinePix Real 3D W3 and the pictures are exactly as you would expect to see for stereo seperation.
A camera with narrow spacing effectively shrinks the viewer, to simulate your eyes being that close together in real life.
https://www.flickr.com/photos/ffr_cobra/sets/72157637945670264/
These are some stereo pairs where you can see the seperation by flipping back and forth between left and right images.
The images are stunning in the rift, using Stereo Viewer.

"Roaster" wrote:
Perhaps I'm being simplistic, but a camera with proper lens spacing does away with any problems of scale. I use a Fugi FinePix Real 3D W3 and the pictures are exactly as you would expect to see for stereo seperation.

Yes, that's correct.

However, I'm trying to determine if I can somehow compensate for closer lens spacing by using wider angle lenses and software to compensate for the distortion. In this scenario, I'm trying to figure out if the stereoscopic effect will still work well at a distance greater than, say, 2' or so from the camera lens.

Personally I doubt it will help. A narrow separation gives two very similar images, and the wider the separation the more parallax change. You just can't fake it without infilling what was or was not obscured by foreground objects.
Can you access that link and see the cave images? Flip back and forth between a pair of right /left images and observe the parallax change. There's no way to synthesize that.

Like I said, it is all about the subject matter. Small IPD is better than wide IPD (or even typical human IPD) for close-up macrophotography and for scale models (making them appear lifesized).

Even a human-like IPD is totally inadequate for photos from aircraft or satellites.

3D photos of the sun are taken from a pair of satellites orbiting far apart:
http://en.wikipedia.org/wiki/STEREO

Once again, appropriate IPD depends on your choice of subject matter.

It may also be useful to use a different IPD for artistic purposes, such as to make the VIEWER appear larger or smaller than life (through the eyes of a giant, or through the eyes of a child). This can be especially relevant to video games and VR, and more so for "3D Camera Lens pictures viewable in the Rift".

Agree completely. Now about the question ... given a fixed IPD for a camera, how does a change in the convergence angle affect the image. In other words, the optical angle between the lenses can be made more parallel or cross-eyed for different subjects. My guess is that it mimics the human need to change convergence with distance in the camera, according to depth of focus, but could it be used to some advantage for the problem of having a camera with narrow lens spacing?

"Roaster" wrote:
Agree completely. Now about the question ... given a fixed IPD for a camera, how does a change in the convergence angle affect the image. In other words, the optical angle between the lenses can be made more parallel or cross-eyed for different subjects. My guess is that it mimics the human need to change convergence with distance in the camera, according to depth of focus, but could it be used to some advantage for the problem of having a camera with narrow lens spacing?

According to Paul Bourke (a noted expert in the field), pointing the camera inward (toe-in) is incorrect:

"

Off-axis (Correct)
This is the correct way to create stereo pairs. It introduces no vertical parallax and is therefore creates the less stressful stereo pairs. Note that it requires a non symmetric camera frustum, this is supported by some rendering packages, in particular, OpenGL.



Objects that lie in front of the projection plane will appear to be in front of the computer screen, objects that are behind the projection plane will appear to be "into" the screen. It is generally easier to view stereo pairs of objects that recede into the screen, to achieve this one would place the focal point closer to the camera than the objects of interest. Note, this doesn't lead to as dramatic an effect as objects that pop out of the screen.

The degree of the stereo effect depends on both the distance of the camera to the projection plane and the separation of the left and right camera. Too large a separation can be hard to resolve and is known as hyperstereo. A good ballpark separation of the cameras is 1/20 of the distance to the projection plane, this is generally the maximum separation for comfortable viewing. Another constraint in general practice is to ensure the negative parallax (projection plane behind the object) does not exceed the eye separation.

A common measure is the parallax angle defined as thea = 2 atan(DX / 2d) where DX is the horizontal separation of a projected point between the two eyes and d is the distance of the eye from the projection plane. For easy fusing by the majority of people, the absolute value of theta should not exceed 1.5 degrees for all points in the scene. Note theta is positive for points behind the scene and negative for points in front of the screen. It is not uncommon to restrict the negative value of theta to some value closer to zero since negative parallax is more difficult to fuse especially when objects cut the boundary of the projection plane.



Rule of thumb for rendering software
Getting started with ones first stereo rendering can be a hit and miss affair, the following approach should ensure success. First choose the camera aperture, this should match the "sweet spot" for your viewing setup, typically between 45 and 60 degrees). Next choose a focal length, the distance at which objects in the scene will appear to be at zero parallax. Objects closer than this will appear in front of the screen, objects further than the focal length will appear behind the screen. How close objects can come to the camera depends somewhat on how good the projection system is but closer than half the focal length should be avoided. Finally, choose the eye separation to be 1/30 of the focal length.

© Copyright Paul Bourke

Partial quote used under the Fair Use Doctrine, without specific permission of the author.

Note that Paul was specifically discussing virtual cameras here, but this should apply to real cameras as well. Also note that "cross-eyed" and "toe-in" are synonymous for cameras pointing inward toward the subject matter, and this can cause asymmetrical vertical distortion making for painful stereoscopic fusion for the viewer of the stereoscopic 3D content. Notice also that he recommends a camera aperture between 45 and 60 degrees (matching the "sweet spot" for your camera setup.

Paul Bourke has a lot more interesting stuff relevant to this topic too:
http://paulbourke.net/stereographics/

Thanks for the link. I was interested in widely spaced cameras (25-50 ft) for distant subjects like clouds, and just knowing they should be parallel will help a lot getting started.

"Roaster" wrote:
Thanks for the link. I was interested in widely spaced cameras (25-50 ft) for distant subjects like clouds, and just knowing they should be parallel will help a lot getting started.

Ah, yes! The XKCD "Giant Head" experiment:
http://makezine.com/2011/10/06/the-xkcd-giant-head-enhanced-depth-perception-project/


(Cross-eyed "giant head" view)

Cross-eyed stereoscopic "no 3D glasses" viewing instructions:
http://www.neilcreek.com/2008/02/28/how-to-see-3d-photos/
http://www.starosta.com/3dshowcase/ihelp.html

Note that stereo pairs can be taken from a single panning camera at different points in time, such as from a side-facing camera on an airplane, to take widely-spaced cloud photos such as embedded above.

For a similar effect using a single video camera (and one darkened eyeglass lens), check out the "Pulfrich Effect". I have a pair of Pulfrich glasses around here somewhere, but you could just remove one lens from a pair of sunglasses to watch a side-panning video to see such perceptual 3D effects.

That's what I'm talkin' 'bout.
I love 3D.
BTW, if anyone is interested in porting images like that cloud formations stuff to the rift, take the image and slipt it into two pieces w/ photoshop or something. Save the images as abc-l and abc-r then open with Stereo Photo Viewer.
It's just amazing when you zoom in and out.

Looking at that stuff, it's a crime that everything hasn't been shot in 3D over the years. This is something we must change.

"Roaster" wrote:
Looking at that stuff, it's a crime that everything hasn't been shot in 3D over the years. This is something we must change.

A lot of WW2 military footage was filmed in 3D. Here is a sample (be sure to set YouTube 3D ON):




You may want to choose "Side by side" 3D option, and perhaps "Swap eyes" option. That video looks great in cross-eyed view, but would be even better in a Rift.