World Shape ?

[Ron]

Hmmm, no I don't think that's right. If I am not mistaken, a Mercator is a rectangular representation (the most common one you see of a map), and shows significant distortion along the E-W direction esp as you get closer to the poles. It's the one that makes Greenland look the size of the United States

Of course, I could be wrong.

Ron

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[Paul Crocker]

I should have clarified that I am not a cartographer but I do play one on TV ....some old US TV humor there! Actually, I have a cartographic background (I use satellite imagery and ancillary data to produce natural resource-oriented maps), but my recollection of ALL of the possible projections out there(there are close to a hundred in common use, with innumerable modifications to each of those) is a bit rusty. I tend to use only a few projections most of the time, since I am dealing with much smaller land areas (usually sub-continental and smaller). I'll look up that "oval with point edges" projection this week to get the exact name for you, Ron. I think it might actually be a Mercator projection, though. There are several Mercator projections in use out there, and the classic one with the "huge" depiction of Greenland is just one of them. That one is created by placing a cylinder around the earth (open ends at the poles), and then projecting the earth's features onto the cylinder. There is another that places the open ends of the cylinder at the equator, and if I'm understanding Ron's description correctly, that might be the one he is talking about...Stay tuned

[Paul Crocker]

Ron: Here's the info you requested about that oval projection with "pointy" edges...it's probably more info than you ever wanted, but I thought I would post it once I'm doing it, since it illustrates how the pros and cons of any projection weigh in.

I'm guessing that you're talking about the "sinusoidal" projection. It's an Equal Area projection, where meridians are curves concave toward a straight central meridian. All parallels (lines of latitude) are straight, parallel lines, and spacing for both decreases toward the poles. The graticule spacing retains the property of equal area. Linear scale is true on the parallels and the central meridian.
It's mathematically based on a cylinder tangent at the equator and may have several
central meridians (interrupted) to reduce distortion at high latitudes. There is no angular distortion along the central meridian and the equator.

It's used as an equal area projection to portray areas that have maximum extent in
the N-S direction.

A great reference for nearly any projection that you'll come across is: the USGS "Map Projections - a working Manual" by John P Snyder, and it's also referred to as USGS Professional Paper 1395 (1987)

Long answer to a short question

[Ron]

Yep, that sounds like our data structure all right. A sinusoidal projection, huh? Cool, thanks for looking that up for me Paul.

Ron