The Principle of Interactive Projection Technology

The operating principle of the interactive projection system is to capture and shoot the target image (such as a participant) through a capture device (sensor), and then analyze it by the image analysis system to generate the motion of the captured object. So that the interaction between the participants and the screen is tightly integrated.

The light projected by the projector is the visible part, and its infrared part is filtered out by its internal filter film, so that for the camera, it cannot see what the projector projects. 
If the infrared is strong, the camera can see the human body. 

How to enhance the image of the object seen by the camera, fortunately, the infrared active emission technology on the market is very mature, for example, the night vision camera sold on the market can emit near infrared (850 nm), and the power is more Large ones have special long-distance infrared lights, but the current night vision camera can reach a distance of 5 m, so it is not needed. 

The night vision camera actively emits infrared light, and then the ccd sensor accepts infrared light. Then the most difficult part of interactive projection, the human body and the background virtual object are resolved. The camera obtains a black and white monochrome background including the image of the person. 

The next step is to detect the motion of the human body, using the image difference technology. The difference is to subtract the two consecutive frames of images obtained by the camera, so what is the result, and the motion part is obtained, so as long as the person is moving, the difference will intercept the moving part. 

The next step is to analyze the data, and then project the virtual part. Of course, complex interactive projection is not just these technologies, these are just the most basic principles. It also involves the calibration of the camera, the optical flow method to find the direction of movement, the optimization of performance, and the special effects.