PARTIcle Shape ANalyzer PARTISAN – an open source tool for multi-standard two-dimensional particle morphometry analysis

Abstract

Volcanic particles are commonly characterized using 2D morphometric analysis. Results of analysis are used to compare particles from different events or phases, and to infer clast-generating mechanisms, eruptive styles and the aerodynamic behavior of particles. Such particle-shape analyses can be made from images of particle silhouettes or cross-sectional slices. A number of different morphometric systems have been used to date, with each using its own nomenclature and mathematical definitions of shape-describing parameters. Some of the parameters can only be obtained using specific commercial software.With the PARTIcle Shape ANalyzer PARTISAN we present a freeware tool which parameterizes 2D shapes and provides a suite of shape parameters, following the different standards of the five most commonly used 2D morphometric systems. PARTISAN enables the user to study and archive the results of particle-shape analysis in a format compatible with various published routines, thus increasing the potential for linking new work with results of work previously published by other groups. It will also allow cross-comparison of results obtained by different morphological routines. We see PARTISAN as a "Rosetta Stone" for volcanological particle morphometry, and it opens the way for development of widely agreed treatment of particle shapes in 2D.

DendroScan: an open source tool to conduct comparative statistical tests and dendrogrammatic analyses on particle morphometry

“…DendroScan reads “.csv” data files as provided by the particle-shape-analysis software PARTISAN 32 . The ".csv" file comprises a list of scanned grains and their corresponding shape parameters (listed in Table 1 ).…”

“…Definitions for each shape parameter are provided in the second column, with p particle perimeter, A projected particle area, w short side of the minimum area bounding rectangle, b long side of the minimum area bounding rectangle, c perimeter of the circle with area A , a maximum intercept, m mean intercept perpendicular to a , L b maximum length of all possible lines from one point of the perimeter to another point on the perimeter projected on the major axis of the particle, W b maximum of all possible lines from one point of the perimeter to another point on the perimeter, projected on the minor particle axis, p cp perimeter of smallest convex polygon around particle, A cp area of smallest convex polygon around particle, e ce perimeter the smallest area ellipse that encloses, but does not intersect the particle, L maj major axis of best fit ellipse, L min minor axis of best fit ellipse, d BC diameter of circle that encloses, but not intersects particle, l F minimum Feret length, w F Feret length perpendicular to l F and d F maximum Feret distance. For further details see Table 1 in Dürig et al 32 . Notation Definition Shape parameter Used by default Remark Morphometric system by Circ_DL Circularity Yes Dellino and La Volpe 2 Rec_DL Rectangularity Yes Com_DL Compactness Yes Elo_DL Elongation Yes Circ_CI 4 Circularity Yes Cioni et al 29 ...…”

“…DendroScan permits analyses based on any of the 23 shape parameters, but since there is repetition of some of them across different systems, only 17 are suggested for comparative analyses 32 . Testing two samples (files) would therefore involve the pairwise comparison of the distributions of 17 shape parameters.…”

“…After segmentation and binarization, particles were represented by black and white images (silhouettes). In the next step, these silhouettes were used as input data for the particle shape analyser software PARTISAN 32 . The resulting data files in csv format are labeled using the sample nomenclature above (e.g., NATang.csv”, “U.csv”) and provided along with this article (see Supplementary Data).…”

“…Starting with a qualitative characterization of ash particles e.g., 7 , 25 – 27 , particle morphometry has evolved over the last quarter century, and various interpreter-independent systems have been suggested to quantitatively describe either the projected shapes or the cross-sections of ash particles in two dimensions. The five morphometric systems most commonly used in volcanology 2 , 28 – 31 have been implemented in recently published open-source software PARTISAN (PARTIcle Shape ANalyzer), which computes 23 dimensionless shape parameters of binarized 2D objects 32 .…”