Re: Rainbows

[P3D Larry Berlin <lberlin@xxxxxxxxx>]

Paul writes:
>Larry Berlin asks "Where are your rainbows with reference to infinity
>in the scenes? Is it
>possible to tell in any of them?"
>
>For the scenes I described, the rainbows are in depth right where the
>water droplets are.  This is nice, because if you have a spray of
>water, you have drops usually throughout a range of depth.
>
>I first had my attention drawn to atmospheric stereo by a comment in
>one of the 1950s books that the air must be crystal clear.  So,
>feeling challenged, I set out to do foggy scenes.  If the fog is in
>puffs and patches, and is sufficiently obvious, it comes out all
>right in stereo.
>
>--Paul S. Boyer   <boyer@xxxxxxxxxxxxx>


Hi Paul,

Your pictures sound really great. I'm reminded of many typical fog and
sunlight scenes I've seen during winters around here. Do you have any of
your scenes on the net?

The geometry of the rainbow's position relative to each eye suggests that IF
one could get a fix on the colors themselves, they would be at the infinity
point of the scene. The physical source of the rainbow is a very strong cue.
It tends to override any perception of the infinity-nature of a rainbow's
projection. A competition of perceptual interpretation similar to retinal
rivalry.

After reading your post I had to go out this morning and make a few rainbows
just to check this out. I'm convinced that it's the infinity thing about
rainbows that makes them seem so elusive. As I stare into the sprinkler-made
rainbow I'm reminded of viewing stereograms: 

(*...  Diverge  your eyes,... * )  ( * ...Diverge your  eyes,  ...*)  

I did the *close one eye at a time* test in the garden. There appeared to be
two rainbows that were displaced from one another by reference to plants and
flowers that were apparently inside the rainbow. This apparent double image
or two rainbows, is really because we are looking at the rainbow out of it's
plane-of-coincidence. If we diverge our eyes onto the two rainbows, there
are two of everything else around us in the same fashion that a splotch of
dirt on a window looks like two splotches when you are looking out towards a
distant scene. Due to the nature of a rainbow, we tend to fixate on the
*splotch on the window* (representing the more solid evidence of matter)
instead of the light coming through the space of the window. To our vision,
each of the two rainbows blends with the other in a kind of sparkling
diaphanous veil effect. Magic in light.  

You're right about the rainbow being created at many of different depths, so
in your shots, you are literally blending thousands of different rainbows
from different depth source points. Or rather blending the infinity
projections from all the source points that coexist on the cone defined by
each camera lens and the sun. That would tend to solidify the apparent
source to a specific group of droplets, and yet if you look closely.... 8 -)
(Does Gabriel do ascii rainbows?)

I have posted some make-believe rainbows on my 3DZine website to illustrate
this. Since they are make-believe they are as if the rainbows were being
projected by only one region of rain rather than thousands. It does however
illustrate the infinity factor one would expect to find if you could look at
one sample slice of rain.

The stereo photo is of a creek here in Rohnert Park, CA taken earlier this
year. (weight shift technique) The rainbow is created and composited
completely in the computer. An animated version of this is in the making...

Enjoy,

Larry Berlin

Email: lberlin@xxxxxxxxx
http://www.sonic.net/~lberlin/
http://3dzine.simplenet.com/


------------------------------

End of PHOTO-3D Digest 1704
***************************
***************************
 Trouble? Send e-mail to 
 wier@xxxxxxxxxxxxxxx 
 To unsubscribe select one of the following,
 place it in the BODY of a message and send it to:
 listserv@xxxxxxxxxxxxxxx 
   unsubscribe photo-3d
   unsubscribe mc68hc11
   unsubscribe overland-trails
   unsubscribe icom
 ***************************