How did we make the table?

1. First Try - Get a Feel of It

To quickly try out the interactive table to get a feel of it, we bought PVC pipes, grab a mirror, and laid frosted plastic sheets over it. This initial setup allow us to get a feel of the position of the mirror, the height of the table, and the size of the projected image. We decided from the initial setup that we would need a bigger mirror to project a bigger image on the table surface.

2. Second Try - Bigger Mirror, More Testing

For our second setup, we used a much bigger mirror. In this setup, we figure out the angle we need for the mirror. We found out that it was difficult to capture the whole image on the table without cutting off the image. We found that the image projected on the table surface was not big enough. We also encounter problem with the recognition. We decided that it may be the folded edges of the plastic sheet that we are using that may be causing problems in recognition.

3. Third Try - The Stand, The Frosted Plexi-Glass and The Table Cloth

After getting the frosted plexi-glass, table cloth, and other materials, we decided to work all night to setup the proper table. To make the projector presentable, we bought a light green cloth with apples outlines so that it matches our farming theme. We made a mirror stand that is exactly 45 degrees so that the project can project on the mirror, and reflect the image perfectly on the table top. We found out that the mirror was not big enough to project the size that we wanted. The bigger problem, however, is that we found out that we have problem positioning the web cam such that it can detect the fiducials accurately. Because of the size of the mirror, we cannot position the web cam exactly under the table to get a clear view. If we were to place it behind the mirror, the web cam would have to be near the table surface, and the web cam does not have a wide enough angle to see the whole table surface. If we were to place it in between the projector and the mirror, the web cam will affect the image projection and more importantly, reflections in the mirror will be captured by the web cam, affecting recognition. If we were to put the web cam by the side, the warp image seen by the web cam made recognition difficult.

4. Final Setup - New Projector Stand, Throw Away the Mirror Stand!

We did more research and tinkering around and decided to throw away our mirror stand. Instead, we place our mirror on the ground and pointed our project downwards. With this setup, only a small portion of the mirror will be projected on the mirror and our web cam can easily be positioned directly under the table for a clear unobstructed view.

reacTIVision

The Colors

We figured out that one of the key to accurate recognition is the colors of the images being projected on the table surface. Because of the images being projected, they are too bright when captured by the web cam. Hence, they affected the fiducials recognition. Hence, we tried to remove all white colors from the game by turing sheep into gray sheep and cows into brown cows. We figure out colors of the same luminosity from colorSYNC so that the web cam can see all the rest of the colors as the same brightness.

The Ambient Light

We tried a lot of variables for the surrounding ambient light and found out that there should not be direct light overhead of the table as it will create a glare. The surrounding should not be too bright or too dark. If not possible, a darker environment is preferred.

Projector Position

We found that the project position is very important to minimize glare from the projector to be seen on the web cam. We managed to isolate the glare on the top of our game. Hence, we purposely place the farm house and the scoring system up at where the glare is such that players do not need to interact there.

Size and Type of Fiducials

We found that the size of the fiducials affect the recognition. The bigger the size, the more reliable the recognition. There are also two types of fiducials, the white on black or black on white types. We found out that the white on black ones work slightly better due to the colors used by our game.

Infrared Solution?

We thought of using infrared solution but after some research and consulting with Maria, we decided not to try it. Firstly, there will be a lot more variables into the whole setup. Secondly, infrared cameras that works properly with the setup does not come cheap. In addition, the infrared concept should bounce within the plexi-glass surface. However, we already bought a plexi-glass surface that is too thin to bounce light within itself.