Terraforming for Fun and Profit

[Continued]

Sprucing up the Base Image

Subtle is the name of the game. Mars is pretty monochromatic, which you kind of come to expect from dead worlds. The first order of business is to get a little color into the old ball. I started by tinting a copy of the base image slightly green. This now what my bottom-most layer in Photoshop looks like:

Then, on a copy of the original image is pasted in the layer above. I choose some areas where I want the green to poke through, and erase them with a soft-edged airbrush. Due to the subtle coloration change, I could afford to be sloppy:

In retrospect, I didn’t have to worry too much about greening the northern hemisphere, for reasons that will soon be apparent. Merge these layers together, and they look something like this:

Adding Oceans

A simple Photoshop trick gives us the boundaries for our wet Mars. Take a copy of the topographic image, and crush the levels as shown below. Choosing just where to crush them will determine the ocean’s edge, but on Mars, the boundary is pretty sharply delineated. The resulting image will be an alpha mask, for cutting up our next image:

Start with another copy of the topo map, and use the Hue/Saturation controls, with “Colorize” checked, to make that map a rich, ocean blue:

Be aware that the dark hemisphere will be the ocean, so we’re not concerned what the southern hemisphere looks like. Add a layer mask to this image, and paste our alpha mask into it:

Because there is not much surface detail on the melted hemisphere, it makes a great ocean, just enough variation to make it believable. Now we paste this on top of our base plate:

Yes! A pretty little planet with a great northern ocean, a good size inland sea, and a great lake thrown in for free! From here, there are a number of tutorials on the net for making 3D globes from cylindrical maps. Here’s a quickie, composted over the requisite gaudy Hubble Space Telescope shot: