Connecting content and annotations with livestroke

One common use for interactive whiteboards (IWBs) is to mark up content provided from a connected laptop. Typically a marking layer is provided which is independent of the laptop content. This leads to problems when the laptop content changes while the strokes in the mark up layer do not. The LiveStroke prototype described in this document uses computer vision techniques to associate the marks with the image of the underlying content from the laptop. For instance, if marks are made on the first page of a document, those marks disappear when the laptop user scrolls to a different page. The marks reappear in the right location on the page when the user returns to the first page. While we have integrated these techniques with interactive whiteboards the techniques are also applicable to screen sharing with mobile touch devices and projectors.