Webots pen camera recognition

I am trying to make a tic-tac-toe game in Webots.

I have 2 robot one that draw circle and the others draw crosses using the device "pen".

I need them to recognise when the other robot draws something, but the camera recognition seems to work only on solid.

Is there a way to make the camera recognise drawings ?

Solution

You should use some image processing library, like OpenCV, to process the camera image and recognize whether a cross or a circle was drawn in a certain square. Using different colors for crosses and circles may also help the image processing to categorize these items efficiently.