The 3D Printed Universe: Tactile Plates

Despite our limited abilities to travel to distant objects in outer space that can be thousands – if not millions or billions – of light years away, astronomers, computer scientists, and other specialists have been creating three-dimensional (3D) models of the stars using data from NASA’s Chandra X-ray Observatory and other telescopes by determining, among other techniques, which of the light is moving away from us and which is moving towards us. This is a major advance that is relatively new in science’s understanding of the Universe.

3D modeling and printing of objects in our Universe open these data sets to the public in new ways as well. If you have access to a 3D printer, we offer free to use 3D files in .stl format of these space-based objects. This allows anyone with access the chance to hold a star, a supernova remnant, a stellar nursery, and other kinds of cosmic objects in the palm of your hand (Arcand et al, 2019).

Chandra’s latest 3D printing program, however, provides a different way to experience astronomical data tactilely. Instead of printing the object in 3 dimensions, this program creates tactile relief plates of two-dimensional images (2D) released as our scientific results are sent out to the media and public. This project is a rapid response to established needs from our community members who are blind or low vision to have “more 3D prints” available and that are available at the same time as the other materials for a public science release that are distributed to the media and public.

Easier to print than full 3D models, these printable relief plates are less complex models that can be printed smaller, faster and/or cheaper at home, at a maker space, or on school 3D printers. These tactile plates are each tested and verified with our consultant Christine Malec, a podcaster and accessibility expert who is a member of the blind community. Coinciding with our press and image releases, and also with our extended visual description program these formats help make Chandra space images be part of a more accessible package.

Links to bookmark

Click here to 3D print a Chandra 3D model
Click here to 3D print a Chandra tactile plate
Click here to access Chandra visual descriptions

How does it work and what is being produced?

Partnering with other members of the BVI community, and using a plug-in developed by Nic Bonne and Coleman Krawczyk in the UK. Nic Bonne is a vision-impaired astronomer who has developed the Tactile Universe project in order to provide a method for translating images into tactile plates, a highly valuable accessible resource. Coleman Krawczyk wrote the code for the plug-in, relatively straightforward to use with Blender, which is a widely-used, free, open-source 3D-modeling program. Nic and Coleman are also responsive to feedback and have offered assistance to help make tactile plates more widely available to the public.

The plug-in works by translating the alpha or grayscale values of an image’s pixels (0 is black, 1 is white, etc) to a height value or distance (in mm) above a plane. Even if the image is full color the grayscale values are still calculated in Blender. An image with higher contrast makes a more palpable relief map however. A pixel that has a grayscale value of 0 (pure black) would be level with the plane of the plate, and a pure white pixel would be set to 1, the highest height above the plane of the plate. The values can then be multiplied to make the resulting topographical relief map more or less drastic, which is set in plain language within the plug-in, where you are provided a table of options, including “Emboss thickness”. Additional settings can be modified, such as adding a “Name plate”, working with borders, noise and spike-removal filters, etc. More advanced Blender users can change the font, decrease the number of polygons in the model, and more. Finished plates can then be exported in the desired 3D-printable format (stl, obj, glb, etc). Visit the tactile universe page for a step-by-step instructions and the downloadable plugin.

Our tester on the tactile plates has been providing feedback on the prints as they are developed. One issue that has been highlighted is the use of fonts. The default font that Blender provides has extra curves, which can be more difficult to discern when reading the nameplate by touch. This issue is being addressed by selecting a different default font. Please let us know if you have a favorite font for low-vision users. In the meantime, we are experimenting with creating our own font for this purpose.

Examples of Tactile Plates

Below are two examples of the 3D tactile prints based on recent Chandra image releases.

The first is Zeta Ophiuchi (fig. 1), a star about 20 times more massive than the Sun with a shockwave to the lower left. The image release contains X-ray data from Chandra (blue) that shows the star in the center of the image, while infrared data from Spitzer (red and green) reveal the shockwave and thinner fainter clouds that streak across the image. The tactile plate of Zeta Ophiuchi in the physical relief map based on the intensity of both the X-rays from Chandra and the infrared Spitzer data. In other words, the more intense the light, the bigger and higher the height on the tactile map.

Fig. 1: Zeta Ophiuchi, shown on the left as a tactile plate, or relief map, of the composite image on the right. The composite data consists of X-ray data from the Chandra X-ray Observatory and Infrared data from Spitzer.

The second example of a tactile plate is of the region very close to the supermassive black hole at the center of the Milky Way known as Sagittarius A* (or Sgr A* for short). This image comes from radio data captured by the Event Horizon Telescope (EHT), a network of telescopes around the globe that can be combined to create very detailed images. The EHT allowed scientists to get the first-every image of the event horizon – that is, the point of no return – around Sgr A*. The tactile print features the event horizon as a diffuse ring with three bright spots, which is also seen in the image.

Fig. 2: Sagittarius A*, our Milky Way’s black hole, shown on the left as a tactile plate, or relief map, of the radio image on the right. Both versions of Sgr A* depict radio data gathered by the Event Horizon Telescope (EHT).

Both of these examples can be downloaded and 3D-printed allowing learners to touch and explore the data. The benefits also extend beyond blind and low-vision users. Many people have reported to our program such different modes beyond sight as being useful and engaging in learning new content and concepts. The Chandra group will continue to explore this “rapid response” 3D printing project as an expansion of our ongoing accessibility work. As always, we will refine and adapt the projects as we learn more about our users and their needs.

This project was developed by the Chandra X-ray Center, operated for NASA by the Smithsonian Astrophysical Observatory with funding from NASA under contract NAS8-03060. Some additional support comes from NASA’s Universe of Learning (UoL). UoL materials are based upon work supported by NASA under award number NNX16AC65A to the Space Telescope Science Institute, working in partnership with Caltech/IPAC, Jet Propulsion Laboratory, Smithsonian Astrophysical Observatory.

by Kimberly Arcand & April Jubett