VERNIER: an open-source software pushing marker pose estimation down to the micrometer and nanometer scales

2025-10-03

AI Summary

Addressing the challenge of high-precision, large-range (centimeter-scale) six-degree-of-freedom pose estimation—requiring nanometer-scale translational and microradian-scale rotational accuracy—in microscopic imaging, this paper proposes a robust localization method based on pseudo-periodic markers and phase demodulation. Our key contributions are: (1) a multi-scale pseudo-periodic pattern design that simultaneously enables wide-field coverage and sub-pixel resolution; (2) a phase-based adaptive local thresholding algorithm, significantly enhancing robustness against noise, defocus, and partial occlusion; and (3) a unified, open-source pose estimation framework integrating pattern coding with phase demodulation. Evaluated on both synthetic and real microscopic images, the system achieves ≤100 nm spatial resolution and ≤10 μrad angular accuracy. All source code and datasets are publicly released to ensure full reproducibility for high-precision micro/nanoscale positioning applications.

Technology Category

Intelligent Robots: Localization, Mapping, and NavigationComputer Vision: Biometrics, Face, Gesture & PoseSearch and Optimization: Local Search

Application Category

Security and Privacy: Large-scale security measurementsGraph Algorithms and Modeling for the Web: Representation, reconstruction, and subgraph or motif discovery in Web-related graphsUser Modeling, Personalization and Recommendation: On-Device user modeling, personalization, and recommendation

Abstract

Pose estimation is still a challenge at the small scales. Few solutions exist to capture the 6 degrees of freedom of an object with nanometric and microradians resolutions over relatively large ranges. Over the years, we have proposed several fiducial marker and pattern designs to achieve reliable performance for various microscopy applications. Centimeter ranges are possible using pattern encoding methods, while nanometer resolutions can be achieved using phase processing of the periodic frames. This paper presents VERNIER, an open source phase processing software designed to provide fast and reliable pose measurement based on pseudo-periodic patterns. Thanks to a phase-based local thresholding algorithm, the software has proven to be particularly robust to noise, defocus and occlusion. The successive steps of the phase processing are presented, as well as the different types of patterns that address different application needs. The implementation procedure is illustrated with synthetic and experimental images. Finally, guidelines are given for selecting the appropriate pattern design and microscope magnification lenses as a function of the desired performance.

Problem

• Achieving micrometer and nanometer scale pose estimation
• Capturing 6DOF object motion with nanometric resolutions
• Providing robust pose measurement using phase-based processing

Innovation

• Phase-based local thresholding algorithm for robustness
• Pseudo-periodic patterns enable nanometer pose resolution
• Open-source software for fast micrometer-scale pose estimation