Framestore recently built a magic school bus for Lockheed Martin that could take children on a trip to Mars. While that might sound like hyperbole — even impossible — it’s one of the most talented studios on the planet, known for making VR experiences for Game of Thrones and The Avengers, among many other projects.

“I mean, how the hell do you turn an entire bus into a headset?” Framestore president Jon Collins asks in the above video from Epic Games.

The answer is that its team used a variety of cutting-edge technologies, including specialized displays that let light pass through before turning opaque, to pull off one of the coolest simulations ever attempted. It’s been more than 20 years since Ms. Frizzle on The Magic School Bus TV show helped introduce a generation of kids to science education through field trips only that bus could take them on. Like virtual reality technology, what was once just a dream of the ’90s is feasible today.

Framestore CG supervisor Theo Jones outlined for UploadVR the technical specifications of the bus and how it as able to pull off a simulation where the kids are driving around the streets of Washington, D.C., one minute and feeling like they are on the surface of Mars the next.

Upload: How did you make the displays transparent?

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Theo Jones: To allow the kids to be seeing D.C. one minute and Mars the next, we designed a configuration of transparent LCD’s backed by switchable film with led backlights sandwiched between. When the kids board the bus the LCD screens are fed a white image, rendering them transparent. When the experience begins an electrical current is fed to the switchable film turning it opaque, the LED backlights are illuminated and the white image on the LCD is replaced by our VR Martian content.

The transparent 84-inch 4K screens cannot just be bought off the shelf. They were custom made for us in China and Korea, by the same manufacturers who supply Samsung. We then had a custom screen fabricator make the mountings to house the screens, switchable film and backlight LED’s.

Upload: How was the location of the bus matched to the scene?

Jones: We started by finding the most accurate maps of D.C. that are publicly available and projecting these onto topographical maps of the surface of Mars generated from NASA surveys. We then adjusted this Martian map to ensure that all the areas that corresponded to roads in D.C., that the bus might conceivably drive down, were navigable and free of obstacles. We then carefully added features and assets to the areas between the roads to add visual interest and match the look of the Martian surface.

One of the trickiest and most crucial parts of the project was solving the problem of tracking the bus in the real world. We soon realised that all the sensors we would need to use to gather the data we required were limited in some way. GPS could give us global location but was not nearly accurate or consistent enough on a small scale, while laser velocimeters and accelerometers are highly accurate but each only supplied a small piece of the puzzle.

So what we realized we needed was a piece of software that could take the outputs from a GPS tracker, a 3-axis accelerometer, a laser velocimeter and a gyroscope and blend them into the millimeter accurate and frame-to-frame consistent data we required, and push this out from our server to our client PC’s with almost zero latency. And this is what we set about designing and then thoroughly testing.

Upload: How many computers were used to render the scenes?

Jones: The bus was mounted with eight custom built high-end gaming PCs using the fastest graphics processors available to power the real-time rendering requirements of four networked computers plus a control server along with two redundant back-up computer to run the show.

A diesel-generator was installed, electrical was run throughout the bus including a breaker box, surround sound installed, bus seats were modified and reupholstered.

We created a bespoke system that allows real-world bus speed, GPS and accelerometer (bouncing up and down, turning right and left, etc.) and incorporated other 4D elements.

Upload: How many speakers did you use? 

TJ: Four 1,000 watt amplifiers, 12 5-by-7 car speakers, and six 350 watt in car subwoofers were installed.

Upload: Is the bus still operational? If so, where is it and what will it be used for?

TJ: We installed one 12 kilowatt, 100 amp, 3-cylinder, 27 horsepower liquid-cooled diesel generator that runs off of the same fuel tank as the bus. The bus itself is a 2008 International IC-CE model school bus. The bus is very much operational still. The “Generation Beyond” campaign from Lockheed Martin continues with an educational tour across America.

This post first appeared on UploadVR.