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This project is meant to realize an economic system that detects in real time the trace of a laser pointer and sends the coordinates to a PC in order to simulate a freehand drawing on a graphic tablet.

The project was born with the purpose of replacing a graphic tablet, which is too expensive, with a much cheaper system that can produce similar performances. The following parts were needed: an hardware in which the code is placed and executed, a comunication system to exchange data between the hardware and a PC, and a device able to capture some kind of signal generated by a freehand drawing. For the harware I used a Raspberry Pi, because it's more powerful that an Arduino, and graphic elaboration is demanding in terms of computing capacity. For the comunication system I used the simplest way: a null-modem connection that exploit the serial ports of both the Raspberry Pi and the PC. Unfortunately Windows doesn't allows the PC to receive serial data and elaborate them at once: you have to use a serial terminal emulator, save the data and then elaborate. Since for this project I used my own PC, which uses a Windows operating system, and I didn't have another one with Linux I decided to be content with this solution. Finally, I chose light to be the signal and so I used a laser pointer to draw and a webcam to capture the drawings.

Paolo Sist, 2015