Automated grain detection and statistics

Much of the data produced by the techniques in our lab take the form of images: EBSD orientation maps, x-ray intensity maps, electron and CL images are all examples of image data. We strive to help you collect your image data in a way that answers your research questions, but often there is more that can learned from images than is immediately obvious to the eye. For example, using our lab’s open-access in-house MATLAB scripting we can extract mineral location and shape data for thousands of grains in a few seconds. In the image below, the x-ray intensities of Ca and P maps are combined to produce a map where bright pixels are the mineral apatite (CaPO4). These contiguous regions of bright pixels are automatically identified and all grains smaller than 10 pixels are excluded.

Example of best-fit ellipses and centroids over thresholded x-ray intensity map

Example of best-fit ellipses and centroids over thresholded x-ray intensity map

The remaining grains are fitted to an ellipse, and various shape statistics are calculated for each grain: area, perimeter, coordinates of the grain’s centroid, major and minor axes, orientation of major axes, aspect ratio, and circularity, for example. These are all exported into a .csv file, and some are plotted up for immediate analysis: the orientation of grain major axes as a rose diagram, illustrating the presence of a shape-preferred orientation for this population of grains; and a grain size histogram with a variety of distribution statistics automatically calculated.

Rose diagram of grain major axis orientations

Rose diagram of grain major axis orientations (0-0.5 probability distribution)

Grain size histogram with lognormal statistics

Grain size histogram with lognormal statistics (2 micron binning)

 

 

 

 

 

 

 

 

Scientific Color Maps for two-dimensional data

The DGS E-beam lab is proud to support Fabio Crameri’s work developing scientifically rigorous, universally readable, and citable color maps for 2D data generated in the lab. Please ask Dr. Orlandini or see Dr. Crameri’s website for more details: https://www.fabiocrameri.ch/colourmaps/