Animating Nebulae with Artificial 3D Parallax

By Norman Chan

Astrophotographer creates stellar animated GIFs and videos using real photos of stars.

Finnish astrophotographer J-P Metsavanio has been taking photos of stars and nebulae for years, but recently started experimenting with converting his photos into three dimensional volumetric models that could be recorded as videos or animated GIFs. The process is a little more complicated than your standard 3D movie upconversion. As Metsavanio explains, the parallax effect (the difference between what your left and right eyes see) is difficult to simulate with a photograph of stars because the distances between objects thousands of light years away is not easy to define. He has to approximate unknown distances using various methods, including even a basic rule of thumb that brighter stars are closer than dimmer ones. Says Metsavanio on his blog:

"My 3-D experiments are a mixture of science and an artistic impression. I collect distance and other information before I do my 3-D conversion. Usually there are known stars, coursing the ionization, so I can place them at right relative distance. If I know a distance to the nebula, I can fine tune distances of the stars so, that right amount of stars are front and behind of the object."

The process of creating a 3D model for the nebula itself in TrueSpace modeling software is even more complex:

"After the first step [gathering the info about the stars], the nebula layer of the image get splitted to an elemets by it’s structure. Then a 3d-mesh is made by the brightness of the nebula. This can be done since the gas in the nebula emits a light of it own and the thickness of the nebula can be estimated by the amount of light.

Then I split the star image to a separate layers by the star brightness and the color index. If there are stars with a known distance, like ones coursing the emission of the nebulosity, I separate them to a different layers, all the steps are done “semi automatic”."

Image Credit: J-P Metsavanio

But the resulting animated gifs are beautiful and mesmerizing. Check them out in Metsavanio's 3D animation posts.