I found this interactive projection mapping --Apro. Map when I researched some interactive examples. Visiters could control the mapping shape through move some black blocks on the wall. The mapping shape's vertexes follow the black blocks number and movements. So in this project, the black blocks are the direct forces. I think it is a playful and appropriate example for this week's theme force. Therefore, I started to think that how to achieve an interactive work like this.
Processing+Kinect(used as web camera)
I knew that the webcam could detect colors with coding about computer vision technology. So I found a good tutorial about how to detect colors in Processing from Daniel Shiffman.
I did the beginning test: detect red color and show white circles where webcam found red colors. So I got some vertexes at where has red colors. Then I made lines between these vertexes so I got a pattern which was composed of circles and lines and could change as the red color dots' number and movement.
Further, I use hand color as the detection color, so the pattern could change as hand's movement. Then I project the pattern on the wall and set up the projector and Kinect's positions to show the hand's shadow on the wall and place the pattern above the hand. So it looks like a magic pattern show and changes above your hand's shadow when you put your hand in front of the Kinect at the end.
Learned the very powerful technology of color detecting. You do not need extra devices, just use the webcam on your computer. I used Kinect because I wanted to get a higher resolution and a better detection result, but the webcam on the computer is also able to do detect color. What surprised me most was that I achieved the unexpected result (the magic pattern above the hand) at the end.