# Monocular Near-Infrared Optical Tracking with Retroreflective Fiducial Markers for High-Accuracy Image-Guided Surgery

## TL;DR

A new monocular tracking system using retroreflective markers achieves high accuracy for image-guided surgery.

## Contribution

A compact, sterilizable, and MRI-compatible monocular tracking system with submillimeter accuracy is introduced.

## Key findings

- The system achieves translational errors of 0.44 ± 0.20 mm and rotational errors of 0.35 ± 0.16°.
- The ArUco MIP_36h12 fiducial family provides the best performance for tracking accuracy.
- The system latency is 32 ± 8 ms, making it suitable for real-time surgical navigation.

## Abstract

What are the main findings?
A monocular near-infrared optical tracking system using compact dodecahedral retroreflective markers achieves submillimeter and sub-degree accuracy.The ArUco MIP_36h12 fiducial family offers the best performance, with translational errors of 0.44 ± 0.20 mm and rotational errors of 0.35 ± 0.16° at distances of 30–70 cm, as measured from static position estimates.

A monocular near-infrared optical tracking system using compact dodecahedral retroreflective markers achieves submillimeter and sub-degree accuracy.

The ArUco MIP_36h12 fiducial family offers the best performance, with translational errors of 0.44 ± 0.20 mm and rotational errors of 0.35 ± 0.16° at distances of 30–70 cm, as measured from static position estimates.

What are the implications of the main findings?
The system offers a compact, low-latency, and high-precision alternative to traditional multi-camera tracking setups in surgical navigation.Its sterilizable, CT/MRI-compatible marker design makes it suitable for integration into image-guided surgical workflows.

The system offers a compact, low-latency, and high-precision alternative to traditional multi-camera tracking setups in surgical navigation.

Its sterilizable, CT/MRI-compatible marker design makes it suitable for integration into image-guided surgical workflows.

Image-guided surgical procedures demand tracking systems that combine high accuracy, low latency, and minimal footprint to ensure safe and precise navigation in the operating room. To address these requirements, we developed a monocular optical tracking system based on a single near-infrared camera with directional illumination and compact retroreflective markers designed for short-range measurement. Small dodecahedral markers carrying fiducial patterns on each face were fabricated to enable robust detection in confined and variably illuminated surgical environments. Their non-metallic construction ensures compatibility with CT and MRI, and they can be sterilized using standard autoclave procedures. Multiple fiducial families, detection strategies, and optical hardware configurations were systematically assessed to optimize accuracy, depth of field, and latency. Among the evaluated options, the ArUco MIP_36h12 family provided the best overall performance, yielding a translational error of 0.44 ± 0.20 mm and a rotational error of 0.35 ± 0.16° across a working distance of 30–70 cm, based on static position estimates, with a total system latency of 32 ± 8 ms. These results indicate that the proposed system offers a compact, versatile, and precise solution suitable for high-accuracy navigated and image-guided surgery.