Optical tracking systems are widely used, for example, to navigate medical interventions. Typically, they require the presence of known geometrical structures, the placement of artificial markers, or a prominent texture on the target's surface. In this work, we propose a 6D tracking approach employing volumetric optical coherence tomography (OCT) images. OCT has a micrometer-scale resolution and employs near-infrared light to penetrate few millimeters into, for example, tissue. Thereby, it provides sub-surface information which we use to track arbitrary targets, even with poorly structured surfaces, without requiring markers. Our proposed system can shift the OCT's field-of-view in space and uses an adaptive correlation filter to estimate the motion at multiple locations on the target. This allows one to estimate the target's position and orientation. We show that our approach is able to track translational motion with root-mean-squared errors below 0 . 25 m m and in-plane rotations with errors below 0 . 3 ∘ . For out-of-plane rotations, our prototypical system can achieve errors around 0 . 6 ∘ .
Keywords: markerless tracking; motion estimation; optical coherence tomography; tracking systems.