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Comment by leblancfg | Hacker News Reader

Would love to hear how they generated the shadow contours from the Moon to the Earth's surface!

it's projection geometry. You create a geometry object with the earth's surface shape. Another with the moon's surface shape. Then, a light source that emits from a sun's shape. All objects are placed at the appropriate distances, and made to rotate and translate through space according to normal orbits.

Then, you project the light from the sun onto the earth, with the moon in-between. This creates the 2D shape on the earth's surface corresponding to the shadow.

I've set up something very similar to this in Blender, although its floating point precision was too low, so I had to fudge things a bit.

Thanks dehhn. From the LRO picture in the article, you can see that they're actually taking high-precision elevation maps of both the Moon and Earth into consideration, which sounds like something rather computationally intensive. I might be wrong, but I don't think they used Blender to handle that.

I would be curious to hear what tool they actually use, their pipeline, etc.

To the best of my knowledge, it was animated in Maya and rendered with Pixar's Renderman. When I was in that group, we used IDL to do any elaborate calculations needed, and then imported the data into Maya/Renderman. This is exactly what Hollywood does when they have to render a scene that requires a lot of simulation. I can ask Ernie if he used anything special for this production.

That's amazing, thanks so much. Ernie, if you're reading this, great job :)

Depends how high precision those maps are, but I can't imagine it being a very big deal with the right data pruning(you only need to consider elevations near wear earth intersecting sun rays are close to tangential to the moons surface)

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