Search Light

Search Light a lightweight search function for physical objects in instrumented environments. Objects are tagged with optical markers which are scanned by a steerable camera and projector unit mounted on the ceiling of the room. The same projector can then highlight the objects when given the corresponding marker ID.

Basic Setup

projector and camera The projector and camera unit is mounted in the center of the ceiling of the instrumented room. It is connected to the PC by an USB/DMX-Interface and can be rotated both horizontally (pan) and vertically (tilt). The camera attached to the projector is a regular digicam with an image resolution of 4 megapixels. The high resolution pictures are triggered and read out over USB with the camera’s freely available SDK. Each object that should be found by Search Light is tagged by an AR Toolkit marker. Each marker has a large black fringe and an individual small black symbol on a white background. These markers are recognized by the Java version of AR Toolkit.


Search Light performs two main tasks: It scans the room for markers and memorizes the corresponding angles, which are used later to show searched objects.

scan room Scan: The room is scanned by taking slightly overlapping pictures in all horizontal and vertical directions. Each picture is analyzed using JAR Toolkit. Marker IDs are stored in a list together with their position in the room, derived from their position and orientation in the picture and the orientation of the moving yoke when taking the picture.

books in rack Show: After the room has been scanned the user can search for marked objects. The object’s marker ID is looked up and the projector unit moves to the position where this marker was detected during the last scan and projects a bright spot around the searched object.