Astronomy --- Rendering - Background

Published:

10.03.2025

Povray is a 3D development environment that translates text files into 3D scenes. Like in a HTML-File, you write what you want to show, with all the necessary information such as object type, position, size, surface finish, and so on.

Objects such as a box are placed in the middle of the scene, a light source to the right outside the frame, a virtual camera in front of the objects, and then a photo can be taken.

A very simple example and an extremely good tutorial has been put on the net by dear Mr. Lohmüller, which should clarify the matter.

Moon-Surface

One of many ways to deal with geometric objects are so-called Spherical Heightfields.

In case of the Moon, take a rectangular map of the surface with as high resolution as possible, and let Povray place it around a sphere.

Next, a height map (DEM = Digital Elevation Map) is used, with the help of which the previously round sphere is provided with notches and bumps, corresponding to craters and mountains of the Moon. This DEM is a black and white image, where black stands for deep valleys and white for the highest points, the gray values correspond to the intermediate stages.

Height map (DEM) of the Moon

The earth-faced side is covered by the center of the image, 50 percent of the width.
The remaining 25 percent on the left and right show the dark side.
The North Pole is up and the South Pole down, horizontally clearly distorted.
Dark gray areas are lowlands (Mare), light gray areas stand for mountains or very uneven terrain.
A little to the left above the centre of the picture is the large Mare Imbrium, to the right of it the Mare Serenitatis.

Once the preparations are complete, all kinds of things can be done with the sphere.

Place it in the middle, light source to the left, place the camera at a certain distance in front of the sphere, let the scene render, and the crescent moon is ready.

If you do this 1800 times and move the light source 360/1800 degrees clockwise around the scenery after each image, this results in 1800 individual images, all of which look a little different. These 1800 "frames" can be converted into a movie with the FFmpeg program, and you have a cute little homemade video on the hard drive.

That's exactly what I've done several times over the days - the nonsense is a hell of a lot of fun.

What came out of this can be viewed on the page Moon-Renderings - First Results.

Waning Moon on Day 20

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Astronomy --- Rendering - Background

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