Rotate the World
richarddmorey.org
richarddmorey.org
It would be nice to know the advantages of each of these projections, and why they were developed.
If you want formulas, https://pubs.er.usgs.gov/publication/pp1395
If you want to know more, there are many books about cartography.
(On further reading: the https://en.wikipedia.org/wiki/Winkel_tripel_projection looks a bit more 'stretched', but keeps the northern latitudes readable while not exaggerating their size.)
Inspired by http://www.genekeyes.com/Cahill-desk-maps/Cahill-1918-rotate...
I'd like to see actual spheres used for computers. We don't have to stick with fixed 2D projections for electronics. Render the Earth as a sphere centered on the center of the viewport. When zoomed in, it'll look flat (just as the Earth itself looks flat up close) but without the size distortions you get when you scroll e.g. Google Maps far north and south. Zoomed out, you'll see how everything actually relates in 3D space.
I admit I don't quite get that bit about not just being a stand-in for a globe. I thought the main reasons maps aren't globes is just because maps are much easier to store, and because maps can be zoomed in to an arbitrary degree. Computer displays eliminate both of those reasons.
It’s difficult to follow rhumb lines on a globe, and it can also be difficult to follow great circle arcs (depending on how the globe is allowed to spin). Making arbitrary 3-dimensional rotations works pretty well for an unattached ball, but is very annoying to do using existing mouse + multitouch UIs. Comparing shapes, distances, and coordinates of places far apart on the globe is a pain. Globes (and computer displays) are difficult to blow up to very large size, and hard to annotate.
I think spheres are great (to the point that I made myself a spherical chalkboard), but having a sphere (or an interactive orthographic projection) doesn’t replace most uses of other maps.
Interesting. How? Chalkboard paint on a globe? Does it ride in/on a globe carriage?
As long as Africa and Greenland aren't on the same map, it's got almost everything that you want from a map.
Of course, what's best for an interactive map is if it turns into a globe when you zoom out, like Google Earth. instead of being a shitty global Mercator. That's a lot more graphically complex, though.
Admittedly, it is easier for developers who are adding features if you do it as Mercator, but not that much easier (if it has a good API).
Are you talking about the problem with the shape of a Mercator tile becoming absurd very close to the poles, which I wouldn't call "aspect"? Or are you thinking of the equirectangular projection, where the aspect ratio changes to preserve the distance between latitude lines?
The reason not to use a globe is efficiency. Not only is 2D easier than 3D, but you can make Mercator out of tesselated tiles. You can't do that on a globe without having way too many tiles or obvious seams.
And when you pan a Google Map, you're panning a flat Web Mercator projection. If it were a projection of the globe, then everything that's already been rendered would have to be adjusted by imperceptible subpixels to account for the curvature of the Earth.
There may be efficiencies of panning a flat projection, but that is becoming a smaller and smaller issue as devices get more capable.
Also, even when in "map mode", you will often notice that google maps is doing more than that. Go to a place where there are tall buildings (I'm looking at downtown san francisco) and you can see the perspective shift on the buildings as it pans.