Regarding =69.GIAP=TOOZ's query about the map, and major_setback's reply, it's worth remembering that there are several different ways of projecting the surface of a sphere (like the Earth) onto a flat surface (a map), but none of them are 'correct' - they all distort in one way or another. Over the area shown on Oleg's screenshot, this isn't likely to be that noticeable though, so I'd be inclined to suggest the satellite image was distorted. To complicate things further, there may be three different 'norths' to align the map on - Magnetic North, which has the unfortunate habit of wandering around, and currently resides somewhere in Canada, True North, or the direction towards the northern end of Earth's rotational axis, which fortunately only moves slowly (over millennia), and 'Grid North' which is a convenience for cartographers - an arbitrary datum that may match True North at some point on the map, but diverges as you move away, to simplify dealing with the problems of projection. Since Oleg has said he is modelling the Earth as a sphere, he's presumably figured out which projection to use on maps, and to make comparisons, you need to find another map using the same projection, datum etc.
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10-30-2010, 03:09 AM
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