We are often asked to make impossible sounding installations possible, we do this through a combination of knowledge, detailed research, and agile development. We can quickly find out if an installation is possible or if subtle changes are required to turn it into a reality. Once we've decided an installation is feasible, we plan the best processes, then trial prototypes and finally, develop the system.
Our first step in producing the giant interactive book was to research technology that would make the book touch interactive, but remain hidden from view. The more hidden the technology, the more magical the experience.
We started by positioning a Kinect above the book. The Kinect can detect objects in 3D space, it is excellent for body tracking, but not so good for detecting fingers, especially from a distance of 2m. The first prototype that we developed could detect the XY position of a hand, but struggled to know exactly when someone touched the book. This is because the Kinect was not accurate enough to detect if a finger was on a page or 20mm away from it. People are used to being able to use subtle gestures on their mobile devices, a tolerance of 20mm on the touch book was not good enough.
Attempt two used the Kinect to detect the XY position of the person's hand, and an Arduino to detect touch by searching for an electrical current on the page. To make pages with an electrical current we had to use metal sheets. When a person touched the metal page, the Arduino detected a change in current and triggered a touch event.
The metal material used for the pages was aluminium with an acrylic core, the brand name is i-Bond. Scaling up the size of the prototype we found that the pages were too heavy and inflexible, not suitable for a giant interactive book.
Attempt three used a touch foil that is normally found on interactive shop windows. The touch foil has a setting to increase touch tolerance. The tolerance setting is used to detect touch through glass, having a tolerance setting means that the same touch foil can be used on glass windows that are 4mm to 12mm thick. Testing the touch foil we found that we could stack 80mm of cardboard on top of the touch foil and still detect a touch and its position.
Two touch foils were placed on the base of the book. The pages made from Foamex, were then placed on top of the touch foils. The bottom two Foamex pages were glued on top of the touch foils to conceal them.
Each touch foil needed its own PC. We therefore had to develop a networked system that used two PCs, one for each of the touch foils, and a third PC placed above the book that was connected to the Kinect and two projectors.
To detect the page number, we used highly reflective stickers uniquely positioned on each page. Detecting the page number was essential, this is because specific content was developed for each page. The Kinect detected the marker and also detected when a page was being turned, dimming content until the pages were open again.
The end solution worked flawlessly with touch accurate to 0.5mm (a finger tip). Once installed, the system booted automatically, leaving the tech support team to mill about on standby while we went to enjoy a well deserved beer.