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Step 7Finish the touchsurface, position the webcam
This is the last step in the hardware build.
Some light from the LEDs will tend to glow upwards and downwards instead of directly into the Lexan, and that extra glow (light-leak) can cause problems. This extra light can bounce off nearby objects such as walls, screens, ceilings, etc., creating areas of infrared glow that will show up on your webcam display as false touch points. The best way to fix this problem is to add a little extra opaque material above and below the edges of the Lexan touchsurface to block this up-glow and down-glow.
Cut a flat 8-inch by 10-inch frame mat out of cardboard, approximately 1-inch thick and sized to fit just below the touch surface. The inside dimensions of this mat should be 6 by 8 inches, making it basically a rectanglular border 1-inch thick that fits snugly into the space right below the Lexan. If these directions are unclear, take a look at the expanded diagram in Step 5, which includes a drawing of this cardboard mat. This will take care of the down-glow.
Repeat the process on the top side of the touchsurface to block up-glow. If you have the time, it looks more professional to use something nicer looking (like some floor or ceiling edge molding) for the up glow blocker, but we just used a second cardboard mat and it works just fine! At this point, you have a touchsurface sandwich, with the Lexan and frame in the middle, and the up-glow and down-glow blockers on the top and bottom, fit snugly into place and held there by crazy glue if desired.
To finish your hardware setup, you just need to place the webcam. It needs to sit approximately 1.5 to 2 feet from the touch surface, pointing at the 'bottom' side of the Lexan (eg. the side not being touched). You can accomplish this by using a cardboard box. Stand the box up so that its height is 1.5 to 2 feet (which side you stand it on will depend on how big your box is). Your webcam will sit inside the box, and your touchsurface will sit on top of the box, so you will need to cut a hole in the top of the box that is approximately the size and shape of the exposed portion of the Lexan (only the exposed portion, not the entire frame!). See the image below for a visual example.
Run the webcam cord out of the box, set the touchscreen on top, and admire the beauty of your completed hardware setup! Now you can peel that protective coating off of the Lexan, if you haven't done so already.
Congratulations! You have finished the hardware for your Mini-Multitouch! If you run your webcam software, you should be able to see the touch surface light up where you put pressure on it, ideally with your fingers.
On to the last step: software.
Some light from the LEDs will tend to glow upwards and downwards instead of directly into the Lexan, and that extra glow (light-leak) can cause problems. This extra light can bounce off nearby objects such as walls, screens, ceilings, etc., creating areas of infrared glow that will show up on your webcam display as false touch points. The best way to fix this problem is to add a little extra opaque material above and below the edges of the Lexan touchsurface to block this up-glow and down-glow.
Cut a flat 8-inch by 10-inch frame mat out of cardboard, approximately 1-inch thick and sized to fit just below the touch surface. The inside dimensions of this mat should be 6 by 8 inches, making it basically a rectanglular border 1-inch thick that fits snugly into the space right below the Lexan. If these directions are unclear, take a look at the expanded diagram in Step 5, which includes a drawing of this cardboard mat. This will take care of the down-glow.
Repeat the process on the top side of the touchsurface to block up-glow. If you have the time, it looks more professional to use something nicer looking (like some floor or ceiling edge molding) for the up glow blocker, but we just used a second cardboard mat and it works just fine! At this point, you have a touchsurface sandwich, with the Lexan and frame in the middle, and the up-glow and down-glow blockers on the top and bottom, fit snugly into place and held there by crazy glue if desired.
To finish your hardware setup, you just need to place the webcam. It needs to sit approximately 1.5 to 2 feet from the touch surface, pointing at the 'bottom' side of the Lexan (eg. the side not being touched). You can accomplish this by using a cardboard box. Stand the box up so that its height is 1.5 to 2 feet (which side you stand it on will depend on how big your box is). Your webcam will sit inside the box, and your touchsurface will sit on top of the box, so you will need to cut a hole in the top of the box that is approximately the size and shape of the exposed portion of the Lexan (only the exposed portion, not the entire frame!). See the image below for a visual example.
Run the webcam cord out of the box, set the touchscreen on top, and admire the beauty of your completed hardware setup! Now you can peel that protective coating off of the Lexan, if you haven't done so already.
Congratulations! You have finished the hardware for your Mini-Multitouch! If you run your webcam software, you should be able to see the touch surface light up where you put pressure on it, ideally with your fingers.
On to the last step: software.
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