map-projections | 易学教程

how map 2d grid points (x,y) onto sphere as 3d points (x,y,z)

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I have a set of 2d grid points (x,y) that I want to map/project onto a sphere as 3d points (x,y,z). I realize there will be some warping towards the poles as abs(y) increases but my grid patch will only cover a portion of the sphere near the equator so severe warping will be avoided. I'm having trouble finding the right equations for that. Paraphrased from the wikipedia article on Mercator projection: Given a "mapping sphere" of radius R, the Mercator projection (x,y) of a given latitude and longitude is: x = R * longitude y = R * log( tan( (latitude + pi/2)/2 ) ) and the inverse mapping of a

Circles in Map Displayed Incorrect Location in D3 V4

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问题 I am using a tutorial to learn how to generate maps in D3.v3, but I am using D3.v4. I am just trying to get some circles to appear on the map (see below). The code works except that the circles are over Nevada and should be in the Bay Area. I imagine this is a mismatch between projections of the map and the projected coordinates. I am not sure what projection the map is in, but I have tried to force it to be albersUsa (see commented out commands where I generate path) but this causes the

how map 2d grid points (x,y) onto sphere as 3d points (x,y,z)

阅读更多关于 how map 2d grid points (x,y) onto sphere as 3d points (x,y,z)

问题 I have a set of 2d grid points (x,y) that I want to map/project onto a sphere as 3d points (x,y,z). I realize there will be some warping towards the poles as abs(y) increases but my grid patch will only cover a portion of the sphere near the equator so severe warping will be avoided. I\'m having trouble finding the right equations for that. 回答1: Paraphrased from the wikipedia article on Mercator projection: Given a "mapping sphere" of radius R, the Mercator projection (x,y) of a given