What sensors do I require to detect multiple objects on a board? I need to know exact numbers of objects and their co-ordinates on the board.

The board can be anything from metal to plastic. And the object I suppose needs to be with a magnet inside.

What ideas or maybe solutions do you have?

I'm thinking to build a scrum board that can transfer data to digital format.

Currently, no writing recognition is needed. Just object detection.

enter image description here


closed as too broad by Matt Young, Samuel, placeholder, Gustavo Litovsky, Chetan Bhargava Nov 2 '13 at 19:45

Please edit the question to limit it to a specific problem with enough detail to identify an adequate answer. Avoid asking multiple distinct questions at once. See the How to Ask page for help clarifying this question. If this question can be reworded to fit the rules in the help center, please edit the question.

  • \$\begingroup\$ You need eyes. What are you trying to build here? A microcontroller project? Can you use a PC and a camera? Please be less vague. \$\endgroup\$ – Samuel Nov 1 '13 at 19:33
  • \$\begingroup\$ @Samuel Added clarification. See the question. \$\endgroup\$ – Pol Nov 1 '13 at 19:37
  • \$\begingroup\$ The objects have writing on them - you'll need a camera to pick the writing up then how would you process the handwriting? \$\endgroup\$ – Andy aka Nov 1 '13 at 19:51
  • \$\begingroup\$ This is almost certainly going to require vision. \$\endgroup\$ – Ignacio Vazquez-Abrams Nov 1 '13 at 19:56
  • 1
    \$\begingroup\$ It is not about writing. For now I just want to detect object on the board. It is not about writing it is about detecting object. Just truing to develop concept. \$\endgroup\$ – Pol Nov 1 '13 at 20:00

Well, there are few requirements listed, so here is one of many completely arbitrary possible answers.

Use peg board with infrared sensors looking through the holes.


You'll need to have a microcontroller (likely with a few slaves) scan the sensors in a grid-like fashion. You'll be trying detect the presence of something blocking the hole, for instance, a post-it note.

That meets you requirements you've listed, but I can't see how you're going to get from here to possibly detecting anything written on the notes. Perhaps you should start with that in mind and work backward from there.

If only you had some sort of method for tracking your progress...


Use a video camera. Even cheap cmos web camera will do the job. The program needed to recognize these bright colored notes should be not so complex. Even something like Raspberry Pi might be enough. Or any PC.


The easiest way is image recognition using a webcam. All you would need is a simple board with two styles of dividing lines. One, like in your picture, is a thick unique color, to separate categories. Alternatively, this can be skipped if you decide to handle categories in software (virtual lines that can be changed with software options). The other lines would be a different color, and thinner. These would make a simple grid running the entire area of the board. Objects could be of arbitrary size as long as they fit inside the boxes in the grid without overlapping the grid lines, and are of a different color from the board background.

This would provide both multiple object detection, and coordinates. If you want arbitrary box sizing, it would be a lot more difficult, unless each object has a separate color.


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