Projector and camera arrangements are provided for use in electronic whiteboard systems. Specifically, the present invention provides projector and camera arrangements wherein the projector and camera share the same imaging optics. By sharing the same projection and camera optics, the distortions that affect the projection system are the same as those of the camera system. Thus, the calibration step required in conventional whiteboard systems where the projector and camera are separate, i.e., each having their own distinct optics and settings, is no longer needed. Further, the arrangements provided in accordance with the invention are self-aligning, even when lens distortions are large and even in the presence of strong perspective effects. The shared optics projector and camera arrangements of the invention also provide for dynamic zooming. In addition, various active and passive optical marker or lightpen designs are provided for use in electronic whiteboard systems.