https://www.cnx-software.com/2012/06/27/baanto-shadowsense-technology-enables-virtual-graffiti-drawings-on-multitouch-displays/
Baanto ShadowSense Technology Enables Virtual Graffiti Drawings on Multitouch Displays - CNX...
Jun 27, 2012 - Baanto ShadowSense is a new 2D and 3D tracking technology using sensors that allow the system to determine the relative angle and as well as other
virtual graffitimultitouch displaysshadowsensetechnology