[Proj] Re: A Cornucopia of Map Projections

strebe strebe at aol.com
Tue Nov 4 18:10:14 EST 2008

Hi, Paul. Good to hear from you, and thanks for the kind words.

The coloring technique arose out of my own experiments. It's not noted on the graphic, but there is a an important subtlety at play: if the distortion representation is "contone" (continuous-tone) then the projection is neither equal-area nor conformal. This representation works well in simultaneously comparing and contrasting areal "flation" (inflation/deflation) and angular deformation (or "torsion" on the graphic).

If, on the other hand, the distortion is represented in discrete gradations, then the map is equal-area (magenta) or conformal (green). In these cases the gradations are important because otherwise there would be little for the brain to contrast against. The brain strongly prefers relative judgments over absolute. If you were to see just a gradual gradation of tone, you could not reliably judge whether two separated parts of the map have similar distortion. The gradations serve as isocols (isomegeths or level curves) with the additional service of conveying magnitude.

Thanks & regards,
-- daan Strebe

On Nov 4, 2008, at 1:54:23 PM, "Paul B. Anderson" <pbander at cavtel.net> wrote:
- Daan,
You have obviously spent a lot of time on this and produced a really nice graphic! Is the programming technique you used based on the multi-color experiments by Keith C. Clarke and Karen A. Mulcahy, or are the graphics based on your own experiments?
I'll definately pass your link around!

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