Tiny Drifters

Part of Exhibition: The Open Sea

Topic: Life Sciences Subtopic: Diversity of Life

Case Study

of an Exhibit

by Jim Spadaccini

Published on September 08, 2011, Modified on November 06, 2014

  • Description and goals

    Tiny Drifters allows visitors to “peer into a magnified drop of sea water” to see and interact with 3D rendered versions of microscopic sea life on a huge, seven-foot multitouch wall. Visitors can rotate and view a variety of types of phytoplankton and zooplankton.

    Last year, when the Monterey Bay Aquarium first presented the idea for the exhibit to us we were immediately drawn to it. We loved the idea that visitors could “touch” plankton, the tiny life forms so essential to all sea life. In addition, the form factor, a huge, round (“aquarium tank-like”) design was equally appealing.

    In our role developing the custom hardware, both the size and round shape both presented enormous challenges. While we had a lot options to make the exhibit work and a fair amount of experience to draw on, a seven foot round multitouch wall with a contiguous surface, better than HD resolution, and unlimited touch points was a very unique request.

    When we began the project, Monterey Bay Aquarium shipped us a nine-foot fiberglass ring with a seven-foot opening for the display surface. The piece was literally too big to fit inside our space, so we walled it in our studio’s portal. (We’ve since moved to a larger facility, in part, to better handle large installations like this one.)

    Once we secured the ring, we worked on the projection surface and protective glass. We used glass produced by Sevasa (based in Barcelona). The glass has a micro-etch that has a textured feel, making it easy for fingers to glide along the surface. The glass also hides fingerprints and reduces glare. The thick 10mm tempered glass, which we used, is extremely durable. Moving and installing the glass was the hard part due to its size and weight, but other than that, this aspect of project was simple.

    The projection surface was another mater entirely. Most projection screen materials are not available beyond six-foot rolls. Since most screens are used for viewing from a great distance, the project material can be easily tiled and the seams won’t be visible. With a seven-foot wall that would be an arms-length away from visitors, we needed to source seamless projection material large enough to cover the complete surface.

    After quite a bit of research we found some great projection material available in our size. The material came adhered to acrylic (which we placed just behind the glass). The dark grey acrylic (1/4″ Cine 13 Optical Coating) is from a company called, Draper. It helped serve up a bright, crisp image.

    We had only a few feet to work with behind the exhibit, so our choices were limited when it came to projectors. We selected two high-resolution short-throw projectors to create the 7-foot image. By blending the two images, we were able to achieve a better-than-HD quality 2560 × 2560 pixel image. The projectors (dVision 35 WQXGA) were purchased from a company called, Digital Projection.

    The blending hardware (Fusion 3D) was also purchased from Digital Projection. At first, we looked at software solutions for blending, a few of them used the corners of two project images to calibrate. This software was obviously wasn’t going to work with a round image. The remainder of the various software blending packages weren’t compatible with the 3D rendering software, Unity that was used for the project. Hardware wound up being the only viable option.

    The final challenge was to add touch interaction. We originally thought we might be able to use an optical method called, Diffuse Illumination (DI). With DI, the screen is flooded with infrared light. As visitors touch the screen, their fingertips reflect invisible infrared light, IR cameras are then used to image and track the touch points. We have used this method in the past with great success, but not with the new projection material that we were looking to utilize. After some initial tests, it became clear that the specialized acrylic we were hoping to use was blocking too much of the IR light.

    Instead of DI with decided to use LLP or Laser Light Plane. This method of illumination uses low-powered infrared lasers positioned on the outside of the surface. The tracking method is same as it with DI. We had previously experimented with this method and had kept it in mind as an option.

    We had a big advantage in using LLP due to the fact that screen was round. We were able to position the low-powered IR lasers at even distances around the screen (we protected them with a custom steel bezel). Most projected surfaces are not round, and in prior testing with LLP we found that getting an even application of IR light from lasers positioned around a rectangle is very difficult. Here the round form factor was working in our favor!

    I should mention here too, that the lasers we are using are less than 5 milliwatts and are safe. The fact that they are retracted inside the bezel and behind IR plexiglass makes their effective output a bit lower. Also, the IR beams are just a few millimeters above the glass surface, making it very unlikely that visitors would interact directly with any of the lights.

    The system we designed uses four Point Grey cameras and NUITEQ’s Snowflake software for IR point tracking. They system can detect as many 100 simultaneous touch points, allowing multiple to interact at the same time. We built a large aluminum frame using Bosch aluminum to hold the projectors, cameras, and other components in place.

    Lindsey Digital developed the beautiful 3D plankton and the interactive software and Monterey Bay Aquarium developed the concept, produced the project, and developed the content. This was the first project we’ve been involved where we have focused solely on hardware. Yet, we still found the work very challenging and rewarding. Paul Lacey at Ideum helped lead the team at Ideum that tackled the engineering challenges this exhibit presented.

    I hope this case study is helpful for others trying to develop large-scale multitouch and multiuser interactive exhibits. There is a video, more pictures, and details about this project our blog: www.ideum.com/blog

Latest Comments (1)

Visitors love it!

by Eric Nardone - September 15, 2011

Hello,

Just wanted to add that it was a great experience working with Ideum on this project. We ran into many technical challenges, but Ideum rose to meet them all. I had no idea at the outset, what a technically challenging experience we had designed. We feel fortunate to have picked contractors who were all up to the challenge.

And in the end, visitors really enjoy interacting with the wall. Which is what it’s all about. Check out this video posted by one our visitors…

http://www.youtube.com/watch?v=5DT7T4dyd6Q

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