Sharing projector-camera workspaces

1. A method comprising:

using a first projector-camera system to project a first video onto a first surface and to capture a second video of the first surface while the first video is projected onto the first surface;

establishing communication between the first projector-camera system and a second projector-camera system, such that the second video is transmitted to the second projector-camera system and such that video of a second surface of the second projector-camera system is received by the first projector-camera system and forms part of the first video; and

reducing video echo between the first projector-camera system and the second projector-camera system through at least one of:

adjusting a white balance of a camera in the first projector-camera system to reduce the video echo; and

increasing an intensity of light to the first surface to reduce the video echo.

2. The method of claim 1 wherein applying light comprises applying light such that the first video is still visible on the first surface.

3. The method of claim 1 wherein applying light comprises applying infrared light.

4. The method of claim 1 further comprising increasing the intensity of the light until video echo is canceled.

5. The method of claim 1 wherein increasing an intensity of light comprises applying light to the first surface and sending a signal to the second projector-camera system indicating that light has been applied to the first surface.

6. The method of claim 5 wherein increasing an intensity of light further comprises receiving a signal from the second projector-camera system indicating that light has been applied to the second surface, determining that video echo has not been canceled and increasing the intensity of light applied to the first surface.

7. The method of claim 1 further comprising automatically removing the light when communication between the first projector-camera system and second projector-camera system ends.

8. A system comprising: a projector that projects a first video onto a first surface; a camera that captures a second video of the first surface while the first video is projected onto the first surface; a network interface that communicates with a second system to send the second video to the second system and to receive a third video that forms part of the first video; a light source separate from the projector that directs light so that it is captured by the camera so as to reduce video echo between the system and the second system; and a light controller that controls the intensity of light from the light source to achieve the reduction in the video echo wherein the light source controller automatically reduces the intensity of the light source when the network interface stops sending the second video to the second system.

9. The system of claim 8 wherein the light source is an infrared light source.

10. The system of claim 8 further comprising the network interface sending a value to the second system to indicate that the light source is on.

11. The system of claim 10 wherein the network interface receives a value indicating a second light source of the second system was turned on and in response to the received value, the light source controller determines whether the intensity of the light is to be increased.

12. The system of claim 8 further comprising an input device wherein the first video further comprises image data generated by a processor based on values from the input device.