Re: Rainbows in 3D?

[P3D <CJMCE@xxxxxxxxxxxxxxxx>]

Bill Davis said;

>When I first read of the suggestion that rainbows would look cool in 
>hyperstereo I thought, wait a minute, doesn't every POV provide a 
>"different" rainbow one which ids a reflection/refraction of the sun-
>light behind the viewer?  Since rainbows don't really exist in one 
>spot there's no way you could get a hyper of one.

>Then I thought, but what -would- it look like?  The rainbows would seem 
>to occupy different positions relative to fixed f.g. and b.g. objects.
>I'm afraid my education limits me at this point.  Perhaps someone else 
>could offer an idea of which "direction" the rainbow would seem to go 
>between left to right views and what degree of apparent movement one 
>might expect?  Maybe rainbow hypers are possible after all.

The Nature of Light & Color in the Open Air by M. Minnaert, Dover 1954:

Rainbows - Chapter X - pp. 167-234

A brief part:  The rainbow is part of a circle; the first thing that occurs to 
us is to make a rough estimate as to where its center lies, that is to say the
direction in which we see that central point.  We notice immediately that this
central point lies below the horizon and we easily find that is is the point to
which the prolongation of the straight line from the sun to the observer's eye
(after penetrating the earth) is directed: that is the ANTI-SOLAR POINT.  This
line is the axis to which the circle of the rainbow is attached like a wheel.
The rays from the rainbow to the eye form a conical surface; each of them makes
an angle of 42 degrees (= half the angle at the vertex of the cone) with the 
axis.

Always look for rainbows in a direction 42 degrees away from the anti-solar 
point, and preferably against a dark background.  If we move, the rainbow moves
with us; it is not an object, it is not visible at a definite place, but in a 
definite direction.

I purchased that book when I was 13 years old; one of the neatest books I own.

Clifford J. Mugnier  (cjmce@xxxxxxx)
Topographic Engineering Laboratory
Department of Civil & Environmental Engineering
University of New Orleans
New Orleans, Louisiana  70148
Voice: (504) 280-7095
FAX:         280-7095


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