The Hubble Space Telescope has been zipping around our planet for over 28 years providing us with unparalleled views of the farthest reaches of the universe. In celebration of this milestone, and in keeping with past tradition, we have prepared a visual feast showcasing a rich and vibrant region of the Milky Way galaxy known as the Lagoon Nebula, or Messier 8. The Hubble image of this region concentrates on the bright core of the nebula, showing in Hubble’s exquisite detail, a glimpse of the turbulence surrounding young hot stars as their stellar winds sculpt the surrounding gas and dust into a cosmic topiary. In fact, as the imagery came together and we shifted our focus to producing visualizations based on the data, we gravitated towards this idea of a cosmic sculpture garden as a guiding force throughout our work.
Our visualization team are no strangers to three-dimensional visualizations of Hubble data, and we saw with the Lagoon Nebula a chance to explore some new techniques to bring a sense of depth and dimension to an already amazing image. We like to think of it as 2.5D, and we would like to share some insights on the process of creating it here.
Layering the Lagoon
Looking at a wide view image of the Lagoon Nebula, it is clear that this is an immense and complicated structure, and the Hubble image only covers a very small portion of the entire nebula.
We had considered creating a full three-dimensional model of the nebula, but lacking a Hubble view of the whole nebula prevented this. As a result, we decided to focus on creating a sense of depth directly from the two-dimensional image. After consultation with our colleagues here at STScI studying star forming regions, we developed a working sense of the morphological topography of the image and used that to guide our decisions in extracting dimensional information from the image.
Stars and Clouds on the Move
A very strong visual cue for dimension comes in the form of parallax from the foreground stars moving differently than the background imagery. There aren’t many stars in the visible light image of the Lagoon (a result of the narrow band image filters used), but there are just enough to provide that effect as the camera pans across different regions of the nebula. Due to the vast distances typically involved in astronomical visualizations (the Lagoon is 4,000 light years away!), some amount of exaggerated distance and artistic license is employed to create what is ultimately an informative, data-based visualization and the Lagoon is no exception.
The first step in pulling layers out of the Lagoon is to create a version of the image with the stars removed.
Next, we begin the process of isolating different features of the image based on our initial assessment, extracting them as new layers and filling in the background with a reasonable approximation of what we would expect to see behind that feature. This then gives us the raw materials to begin arranging the different features of the nebula and the foreground stars in a three-dimensional space.
Sailing Across the Lagoon
Now that we have the various parts of the image in place, the fun can begin! Using a three-dimensional scene in a motion graphics program, with the layers of the Lagoon arranged in z-space according to our interpretations of the data (that is layered in the third-dimension), one can define a camera move that pans across the scene. Since the layers are arranged at different depths, we can rely on parallax to give the scene its characteristic depth. You can see now why we refer to this as 2.5D, the layers that make up the scene are still two-dimensional, but arranging them in 3D space lends a volumetric feel to the entire scene. Our aim is to provide a more engaging experience beyond just staring at the image that is simultaneously educational and fun.
Finally, we add some acoustic ambience using layered guitars with delays and reverbs to set the scene for cosmic exploration. We hope you enjoy the video and come away from it knowing a little more about the Lagoon Nebula!
Credit: NASA, ESA, and G. Bacon, D. Player, J. DePasquale, F. Summers, and Z. Levay (STScI)