Abstract. We present the design and a prototype implementation of a three-dimensional visualization system to assist with laparoscopic surgical procedures. The system uses 3D visualization, depth extraction from laparoscopic images, and six degree-of-freedom head and laparoscope tracking to display a merged real and synthetic image in the surgeon's video-see-through head-mounted display. We also introduce a custom design for this display. A digital light projector, a camera, and a conventional laparoscope create a prototype 3D laparoscope that can extract depth and video imagery. Such a system can restore the physician's natural point of view and head motion parallax that are used to understand the 3D structure during open surgery. These cues are not available in conventional laparoscopic surgery due to the displacement of the laparoscopic camera from the physician's viewpoint. The system can also display multiple laparoscopic range imaging data sets to widen the effective field of view of the device. These data sets can be displayed in true 3D and registered to the exterior anatomy of the patient. Much work remains to realize a clinically useful system, notably in the acquisition speed, reconstruction, and registration of the 3D imagery.

Accurate registration between real and virtual objects is crucial for augmented reality applications. Existing tracking methods are individually inadequate: magnetic trackers are inaccurate, mechanical trackers are cumbersome, and vision-based trackers are computationally problematic. We present a hybrid tracking method that combines the accuracy of vision-based tracking with the robustness of magnetic tracking without compromising real-time performance or usability.We demonstrate excellent registration in three sample applications.

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Abstract. We report the results of a randomized, controlled trial to compare the accuracy of standard ultrasound-guided needle biopsy to biopsies performed using a 3D Augmented Reality (AR) guidance system. Fifty core biopsies of breast phantoms were conducted by a board-certified radiologist, with each set of five biopsies randomly assigned to one of the methods. The raw ultrasound data from each biopsy was recorded. Another board-certified radiologist, blinded to the actual biopsy guidance mechanism, evaluated the ultrasound recordings and determined the distance of the biopsy from the ideal position. A repeated measures analysis of variance indicated that the head-mounted display method led to a statistically significantly smaller mean deviation from the desired target than did the CRT display method. (2.48mm for control versus 1.62mm for augmented reality, p < 0.02). This result suggests that AR systems can offer improved accuracy over traditional biopsy guidance methods.

We describe an augmented reality, optical see-through display based on a DMD chip with an extremely fast (16 kHz) binary update rate. We combine the techniques of post-rendering 2-D offsets and just-in-time tracking updates with a novel modulation technique for turning binary pixels into perceived gray scale. These processing elements, implemented in an FPGA, are physically mounted along with the optical display elements in a head tracked rig through which users view synthetic imagery superimposed on their real environment. The combination of mechanical tracking at near-zero latency with reconfigurable display processing has given us a measured average of 80 µs of end-to-end latency (from head motion to change in photons from the display) and also a versatile test platform for extremely-low-latency display systems. We have used it to examine the trade-offs between image quality and cost (i.e. power and logical complexity) and have found that quality can be maintained with a fairly simple display modulation scheme.