Re: John!!!

[P3D Jim Crowell <crowell@xxxxxxxxxxxxxxx>]

At 5:15 PM 10/18/96, P3D  William Carter wrote:
>
>I would shoot the surface of some textured sphere. Golf ball, basket ball,
>medicine ball, Earth ball, egg. Pick one.
>Next I would shoot with a zoom lens.
>
[deleted]
>
>Finally, I would show it to an audience, asking them to determine if the
>shape was concave or convex. Plot a graph for where they got it/didn't get
>it, and figure out what happened.
>

That's not a bad start.  Two suggestions: first, make darn sure the focal
length is long enough that the projection is essentially orthographic, or
there'll potentially be  perspective cues for the sign of the curvature.
Second, show people _two_ pictures, one with the surface convex & the other
concave (identical in all other respects) & make them pick which is which.
That way it won't matter if there's a preference for seeing your pictures
as convex, say.

Might be best if your surface was covered with thin, high-contrasts lines,
to give the best possible resolution.  Maybe cylinders (coffee cans, oil
drums, whatever) with pin-stripes?

-Jim C.

----------------------
Jim Crowell
Division of Biology
216-76
Caltech
Pasadena, CA
(818) 395-8337
jim@xxxxxxxxxxxxxxx



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