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Word Adventure, gather letters to complete the word!

This is an interactive installation that aims to combine learning words and fun in devising strategies to gather letters.


Collect letters to complete the word

The letters are dangling at various locations, and only the yellow colored characters can collect them. But these characters cannot jump that high, so players need to put blocks as stepping stones to help these cute yellow fellas to reach the letters. The blocks are generated by touching the screen (wall) and can be removed by touching it again.

System overview

The system is simply a projector and a laser range finder to detect touches on the wall. You may realize the black object in the photo above at the top of the wall. This is the laser range finder and for this project I used Hokuyo's UST10-LX. Content is developed with Unity.

How the touch detection works

Readings from the sensor

This image is the visualization of the data points detected. With the sensor placed on top of the wall looking down, if there are no hands touching the wall the laser beams will reach the floor. This will result in a rectangular shape with the floor points aligning as a straight line. However, if someone touches the wall, its position will be detected as shown in the above image. So to detect the touches we just have to first define the rectangular touch area, and all points that are within this area are touch (hand) points.

Limitations

There are some limitations in accuracy and detection rate. If there are two hands (touch points) that overlap each other from the sensor's point of view, the one on the outer side will not be detected.

Undetected touch point

As shown in the image,  the bottom touch point will not be detected because it is hidden by the other one above it. The black line represents the laser beam that sweeps the wall for obstacles (hand/touch points) and we can see it cannot reach the bottom point.



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