Free, flexible and fast: orientation mapping using the multi-core and GPU-accelerated template matching capabilities in the python-based open source 4D-STEM analysis toolbox Pyxem

TL;DR

This paper introduces GPU-accelerated template matching in Pyxem, enabling fast, flexible, and scalable orientation mapping in 4D-STEM analysis for nanocrystalline materials, supporting real-time applications.

Contribution

The work implements and validates GPU and multi-core CPU acceleration for template matching in Pyxem, enhancing speed and scalability for 4D-STEM orientation mapping.

Findings

Achieved significant speedup with GPU and multi-core CPU implementation.

Validated the method's accuracy through comparison with existing techniques.

Demonstrated real-time orientation mapping in TEM experiments.

Abstract

This work presents the new template matching capabilities implemented in Pyxem, an open source Python library for analyzing four-dimensional scanning transmission electron microscopy (4D-STEM) data. Template matching is a brute force approach for deriving local crystal orientations. It works by comparing a library of simulated diffraction patterns to experimental patterns collected with nano-beam and precession electron diffraction (NBED and PED). This is a computationally demanding task, therefore the implementation combines efficiency and scalability by utilizing multiple CPU cores or a graphical processing unit (GPU). The code is built on top of the scientific python ecosystem, and is designed to support custom and reproducible workflows that combine the image processing, template library generation, indexation and visualisation all in one environment. The tools are agnostic to file size and format, which is significant in light of the increased adoption of pixelated detectors from different manufacturers. This paper details the implementation, validation, and benchmarking results of the method. The method is illustrated by calculating orientation maps of nanocrystalline materials and precipitates embedded in a crystalline matrix. The combination of speed and flexibility opens the door for automated parameter studies and real-time on-line orientation mapping inside the TEM.