I've been offered a commission to make a world map for a science fiction setting. The publisher wants a terraformed planet meant to be a replacement for Earth. The art director wants land masses that are overall similar in area to Earth's, and thus similar ocean areas. He wants similar polar ice caps, tropics at the equator, and so on. My guess is he anticipates a similar distance from a similar star, a similar planetary axis tilt, and the familiar climates and weather patterns that ensue. Who knows. He may even want a similar moon and tides.

He asked for a flat map with straight vertical, not curved, longitude lines. He also wants a separete, more detailed continent map, and probably will seek more continent maps hereafter.

This poses a problem. Sci-fi fans, I fear, won't overlook the land-mass distortion arising from a flat map whose polar regions run the full length of a horizontal image. I'll give him the globe map he requests, but I'd prefer to base the continent map on a better projection that takes the spherical nature of the planet into account, so it's not radically distorted.

How do I transform such a horizontal map into a globe map? What program does this best? Do we have a tutorial? My sole expertise is Photoshop. Please help!