CapCam: Enabling Rapid, Ad-Hoc, Position-Tracked Interactions Between Devices

We present CapCam, a novel technique that enables smartphones (and similar devices) to establish quick, ad-hoc connections with a host touchscreen device, simply by pressing a device to the screen's surface. Pairing data, used to bootstrap a conventional wireless connection, is transmitted optically to the phone's rear camera. This approach utilizes the near-ubiquitous rear camera on smart devices, making it applicable to a wide range of devices, both new and old. CapCam also tracks phones' physical positions on the host capacitive touchscreen without any instrumentation, enabling a wide range of targeted interactions. We quantify the communication performance of our pairing approach and demonstrate data transmission rates up to four times faster than prior camera-based techniques. To demonstrate the unique capability and utility of our system, we built a series of example applications, highlighting different interaction techniques CapCam enables.