US Patent 6891518 Augmented reality visualization device

A head-mounted display system includes an imaging camera for capturing a view of a workspace located below the head-mounted display system, the imaging camera positioned at a downward pitch angle for capturing an image of the workspace. The system further includes a tracking camera aligned in substantially the same yaw as the imaging camera, the tracking camera for capturing a tracking image including a marker structure, and a display which displays a view of the workspace captured by the imaging camera augmented by a virtual image generated by a processor and registered according to the tracking image.