Trackmate is an open source initiative to create an inexpensive, do-it-yourself tangible tracking system. Using the project's Tracker software, any computer can recognize tagged objects and their corresponding position, rotation, and color information when placed on the imaging surface.
Using a system like the one shown here, you can track physical objects on a surface and use them to control and manipulate spatial applications on your computer. Since objects are each uniquely tagged, they can easily be mapped to particular actions, information, or relationships. See the LusidOSC project for more details about spatial applications.
Step 1: Setup the Picture Frame
Start with a 4x6 inch picture frame with a wide border.
Remove the back from the picture frame and remove the glass plate. Optionally, at this point you can sand one side of the glass with special glass/diamond sandpaper (important note: if you sand glass, use water to reduce glass dust since it can be hazardous to breathe) to diffuse the lighting and make the glass look frosted. Standard sandpaper should work too, but it will take a lot more work.
Use a hot glue gun to securely affix the glass to the frame. If your glass is frosted, make sure the frosted side is facing out (i.e., the glass feels rough when touching it from the pretty side of the frame).
Step 2: Build the Faux Hardwood Box
To build the box, gather a couple 3/32 inch x 4 inch basswood (or anything really) boards and a 1/2 inch x 1/2 inch basswood square rod.
Measure the length and width of the picture frame. To create the sides of the box, cut two boards that measure the length of the box, and cut two that measure the width of the box - 3/16 inch (to compensate for the width of the two length-cut sides). Also, cut 4 pieces of the square rod that are 3 inches long each. Always measure everything twice before you cut!
Using the hot glue gun, construct the sides of the box on top of a flat surface. Make sure that the long sides are always on the outside (since the board was cut in the previous step to allow for this configuration). It is recommended to glue the 4 square rod pieces to the edges of the short sides (making sure they are flush with the edge), and then gluing the long sides to them on the flat tabletop.
Finally, sand and stain the box to match the frame. In this case, a dark walnut stain is used to make the inexpensive basswood look luxurious.
Step 3: Install the Webcam
Before the webcam can be installed, the bulky clip should be removed. I used the Logitech QuickCam Pro for Notebooks (which works well in windows), but any decent quality webcam that allows manual functionality (i.e., exposure control and focus) should work. To remove the clip from the same camera used here, remove the tiny rubber piece from the hinge and unscrew the underlying screw.
Use the hot glue gun to secure the camera to the top of the frame. Make sure that the camera view is angled over a bit so that when the image is reflected off of a mirror, it will be centered on the glass in the frame. Also, make sure there will be clearance between the camera and the side of the box so that you can fit everything together later.
Step 4: Install the Lighting
For the lighting, use white LED strips. These lights are low power, stay cool, and give nice uniform light. They are sold for a lot of different purposes, but I found some of the best prices are related to LEDs used for car lighting (such as Oznium's 4.7" white LEDs). If you use LEDs that already have resistors built-in (like the ones mentioned), they can be simply wired in parallel later.
Hot glue two LED strips into the box pointed at slightly different angles. The lights should be mounted on the same side as the camera to reduce reflections and glare potentially seen by the camera.
Solder and glue the connector for the lights to the box. The particular mounting will vary depending on the type of lighting you get, if you want a switch, you have access to a soldering iron, etc...
Step 5: Finish It!
Finally, attach the picture frame to the top of the box with hot glue. Make sure that the webcam and the LEDs are positioned on the same side of the box to keep the lighting from strongly reflecting in the image.
Place a 4 inch x 6 inch mirror on the table and place the box on top. This mirror enable the downward-pointing webcam to actually be looking at the glass surface of the picture frame (alternatively, the webcam could have been mounted directly on the table looking up at the glass, but the box would have needed to be twice as tall, making it bulky and awkward to use).
Your Classy Hardwood Curio is now ready to use. Plug in the lighting, plug in the camera, and get started with Trackmate!