VERNIER: an open-source software pushing marker pose estimation down to the micrometer and nanometer scales
This provides a solution for microscopy applications requiring high-precision pose estimation, though it appears incremental as it builds on previous marker designs and phase processing methods.
The paper tackles the challenge of precise pose estimation at small scales by introducing VERNIER, an open-source software that uses phase processing of pseudo-periodic patterns to achieve micrometer and nanometer resolutions with robustness to noise, defocus, and occlusion.
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.