NXT PORTRAYER ROBOT

The steps to get a portrait are three: make a photo (or load an image), extract the edges to obtain a serie of black lines on white background, and then vectorize the drawing for the robot to understand and draw it. This portrayer robot draws like a real artist, and not like a printer! First, it draws the long lines of the contour, then adds the details, and finally fills the dark areas.

When I was at the Cirque des Sciences in Luxembourg (September 2007), I saw Erik's XY plotter in action, and I thought I should make my own portrayer robot. During a dinner in Luxembourg, Claude Baumann explained to me how to transform a raster image (composed by pixels) into a vector representation. Here is his tutorial about vectorization.

I started building a cartesian plotter like the one seen in Luxembourg, based on the LEGO Technic Control Center plotter 8094. That prototype was really precise, allowing 0.1mm resolution. I showed the first prototype of the portrayer at the Festival of Creativity (Florence) in October 2008. In two days the robot portrayed more than 170 people!

The photos were taken by a webcam on a white background, to help edge extraction. The best illumination is diffuse white, to avoid sharp shadows on the faces.