Shadow Play

Martin Alonso

Robbie Holop

Sudarshan Kadambi

Steven Peng

Introduction

Shadow Play is a museum or classroom exhibit consisting of a "magic box" that projects animated images to a screen about 20 feet away. Children can stand between the projector and the screen so their shadows will also be projected onto the screen. The animations portrayed on the screen depict a simple scenario that the child who is playing can interact with by moving his or her body (and hence shadow).

Objective

Our objective is to build a fun and educational toy for children ages 4 to 7. We have three educational goals for our project:

Projections
The exhibit should teach children the basic mechanics of shadow projections.
Cause and Effect
The exhibit should teach children how their actions can affect events in the future.
Motor Skills
The exhibit should improve children's motor skills by allowing them to track their movements by watching their shadows, and by encouraging them to follow the movements of animated objects.
Colors
The exhibit should teach children about colors and how they are arranged in the spectrum by allowing them to choose colors from the spectrum.

Technology

We considered using several different technologies to create our exhibit:

Light Dependent Resistor (LDR)
Place LDRs at various locations to track the player's movement into and out of those locations. This approach would limit us to a finite number of locations where tracking is available, so we decided not to use it.
Computer Vision
Use computer vision to determine where in the projected scene the player's shadow is. We didn't use this method because it's unreliable when shadows overlap with elements of the scene and because we would need more physical space than was available (camera needs to be placed behind the screen to prevent occlusion from player's body).
Puppets
Give the players puppets with fiduciary markers attached to them. The markers can then be tracked using reacTIVision software. We didn't use this because the puppets can easily be turned at a sharp angle or occluded to prevent the software from tracking it. It also fails our goal of providing a full body experience.
Wii Remote
Use the Wii Remote's infrared camera to track an infrared light we attach to the player somehow (necklace, bracelet, hat, etc.). This is the approach we decided to use for our final prototype.

We created our animations and scenarios in Adobe Flash. We run our Flash application on a laptop connected to a Wii Remote and a projector. Input from the Wii Remote is interpreted by a standalone application called WiiFlash and then routed to our Flash application.

Testing

We first tested some of our basic ideas: projecting shadows, interacting with projected animations, and playing with puppets. The children we tested with enjoyed just playing with their shadows on a blank screen. We also found that they enjoyed making their own puppets more than any of the other activities.

In our final round of testing, we tested some of our animated scenarios. The children seemed to enjoy playing with colors, but even more so, they enjoyed "chasing the arrow," a game they invented when they saw the mouse cursor moving on the screen.

Final Prototype

Our final prototype is a decordated wooden box in which we place our projector, laptop, and Wii Remote. The box is placed about 20 feet from the surface to be projected on. The player wears a hat fitted with an infrared light for tracking. After some quick calibration of the Wii Remote, the application is ready to start.

In our final application, we allow the player to color a number of objects--including a car, fish, and birds--by moving around the screen. The player's location is used to determine the color, which is applied to the object on the screen in real time. Once the player has finished coloring all the objects, there are three particular objects (the bird, hat, and elephant) that return in the second part of the application.

In this part, the hat is displayed above the player's head. The player must try to keep his shadow inside the elephant to hide from the bird, who is flying overhead. The consequences of failure are terrifying: the bird swoops down to the player's head and makes angry bird sounds.

Pictures