3 ms·

Seems like the point should be the data, not the shape of the map. How does changing the projection type alter the information provided in this case?

meepmorp 12y ago
I think (someone can correct me if I'm wrong) that the Mercator projection doesn't represent the area of the map in a way that accurately reflects the proportions. So, the relative sizes of Texas and Maine shown in the map aren't accurate, relate to each other. So the projection would affect the information that the map is conveying, though not in a way you might find important.
sgnelson 12y ago
Yes, you're correct, the point should be the data. However, the projection (not the shape), matters a great deal for a number of reasons. The classic example is to take an orange peel and flatten it. It's impossible to do without tearing or distorting in one way or another. The Earth is of course a 3d shape, and maps are 2d, thus projections to try and map the world as accurately as possible. However, it gets more complicated when you project the data, going back to the distortion. It becomes a problem of "Pick 2 out of 3." That usually means Area, Shape and Direction. You can have an accurate representation of Area and Shape, but not Direction. Or in the case of Mercator, Direction and Shape, but not size. Mercator was used by ocean going navigators so that they could draw a straight line on their navigation charts (as longitude and lattitude lines are represented by rectangles with 90 degree angles). Since then of course, we now have thousands of different projections, used for different purposes so that we can try and create the most accurate mapping of the "real" world as we can. And of course, the projection you choose, should hopefully help you in accurately communicating that geographic information to others. I hope that all makes sense.

meepmorp 12y ago

I think (someone can correct me if I'm wrong) that the Mercator projection doesn't represent the area of the map in a way that accurately reflects the proportions. So, the relative sizes of Texas and Maine shown in the map aren't accurate, relate to each other. So the projection would affect the information that the map is conveying, though not in a way you might find important.

sgnelson 12y ago

Yes, you're correct, the point should be the data. However, the projection (not the shape), matters a great deal for a number of reasons. The classic example is to take an orange peel and flatten it. It's impossible to do without tearing or distorting in one way or another. The Earth is of course a 3d shape, and maps are 2d, thus projections to try and map the world as accurately as possible. However, it gets more complicated when you project the data, going back to the distortion. It becomes a problem of "Pick 2 out of 3." That usually means Area, Shape and Direction. You can have an accurate representation of Area and Shape, but not Direction. Or in the case of Mercator, Direction and Shape, but not size. Mercator was used by ocean going navigators so that they could draw a straight line on their navigation charts (as longitude and lattitude lines are represented by rectangles with 90 degree angles). Since then of course, we now have thousands of different projections, used for different purposes so that we can try and create the most accurate mapping of the "real" world as we can. And of course, the projection you choose, should hopefully help you in accurately communicating that geographic information to others. I hope that all makes sense.