Re: Lighting for 3D

[Jim Beals <kgrafx@xxxxxxxxxxxxx>]

I am no expert, but I'll throw in a few opinions here. I do a lot of single
SLR 3D shots where I move the camera over on a slide bar. One thing to
remember there is Don't use a camera mounted flash, as you will get
different shadows in each view.
If you are making slides (or video or movies) for projection another bit of
information I found to be useful is to try and avoid large contrasts - try
to get as much of an even and soft light as possible.  For hand held slide
views or VM reels or side by side prints this is not a real problem.  The
reason for this is how well the 2 images are delivered separately to the 2
eyes.  In a viewer type situation there is 100% separation of the left and
right views. However, in a projected image (whether it is anaglyph - which I
don't see much talk about here) or polarized (or lenticular prints, LCD
glasses, etc) it is not possible to achieve much better than about 70%
(guess) separation of left and right views. There will always be some
bleed-through or ghosting of the other image.  And this bleed through or
ghosting is most visible in the areas of the image that have high contrast.
A white pilar behind a black wall for instance, will give large contrast and
thus the right eye will see more of 'ghost' of the left image and the left
eye will see more of a ghost of the right image.  So, to reduce the amount
of 'Ghosting' or bleed through for images that intended to be projected it
is best to avoid high contrasts in the image.  Softer shadows will work in
favor of an easier to view 3D image.  If one is intending to use the images
only in a VM or slide viewer, than non of this matters as these systems
deliver 100% separation of left and right views. I haven't tried it, but
more contrast and harsher shadows (up to the point of good photography) may
enhance the depth - but the scene should be properly lite despite it being
3D or not).
Of course '3D' computer images are not stereoscopic and therefore only have
shadows, shading and perspective to convey depth.  But, with stereoscopic 3D
one can make a very deep 3D scene using only sublte shade differences. On a
PC one can generate a background and 3D text and set them to the same
color/tone. Then setup lights in such a way that when it is rendered is has
just a small amount of shading. Viewing only one image (left  or right) it
will be difficult to see the letters or especialy discern much depth or 3D
in the picture, but seen stereoscopically the sublte shading on the letters
are enough information the brain needs, and in stereoscopic 3D you'll see
the letters standing way out from the back ground with real depth.  So, in
the 2D image it will be hard to see anything, in stereo it will be very easy
to see the depth.  You don't require very much shading - some - but not much
to get a good 3D effect. What you need most is the separation of left and
right images. Do the the delivery system of projected 3D that means to avoid
high contrasts and harsh shadows as this gives the less separation in a
projected image.  
Hope this is a little helpful.  


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