Exploring Segmentation Techniques for 

Material Identification in Howardite 

and Chondrite Meteorites

Isabella DeClue

Montgomery Blair High School

Mentor: Jacob LaManna
NeXT Dual Tomography System

• Tomography refers to the imaging of a sample by cross sections through the use of a penetrating 

wave 

• The NeXT dual tomography system allows for simultaneous capture of Neutron Computed 

Tomography (NCT) and X-ray Computed Tomography (XCT) images
Introduction

Side by side comparison of NCT cross-section image (left) 

and XCT cross-section image (right) 

• Because of the difference in the attenuation coefficients of thermal neutrons and 

X-Rays, NCT and XCT images each show different features of the sample

• Meteorites are valuable to use as samples 

because they provide an easy way to study 

the solar system
• Sample EET87503: an achondrite howardite meteorite from the howardite (surface), 

eucrite (outer crust), diogenite (lower crust) meteorite clan, which all formed from 

the Vesta asteroid

The Meteorites

• Sample GRA06100: a carbonaceous chondrite of the class CR2, which are 

differentiated by the presence of chondrules, and Iron-Nickel

Meteorites provided by Allan Treiman, 

Lunar and Planetary Institute
Segmentation

• After image stacks (volumes) are generated from the NeXT system, edited, and registered, the 

process of segmentation begins, where features of interest are isolated from an image and 

analyzed individually 

• Three methods of segmentation were tested on the meteorite stacks and evaluated: a machine 

learning plugin, a superpixelation method, and a phase segmentation program 

Courtesy of Ralph Heckemann
Segmentation: Trainable Weka Plugin 

• Regions from cross-section images are 

traced and added to different groups 

(classes), and a classifier is trained 

based on this training data and applied 

to the whole stack 

• Exceeded certain time and memory 

limits which made it impractical to 

use
• A feature of MATLAB allows superpixels of different sizes 

can be generated, drawn over an image, and 

manipulated

Segmentation: Superpixel Segmentation

• Provided no easy way to combine features of interest 

found in XCT and NCT image stacks 

Superpixels over an XCT cross-section 

image

• An optimal amount of superpixels for each cross-section 

could not be calculated easily
Segmentation: Phase Segmentation 

• Best method: a program written in MATLAB designed specifically to create regions of 

interest considering the Neutron and X-Ray volumes by using a bivariate histogram
Results: GRA Chondrite
Results: GRA Chondrite

• H-Bearing Minerals

• Iron-Nickel and 

Opaque Assemblages

• Type I/II Chondrules 

and Metallic Veins
Results: EET Howardite
Results: EET Howardite

• H-Bearing Minerals

• Diogenite Pyroxene

• Impact Melt Clasts

• Eucrite Pyroxene and Plagioclase
Conclusions

• Phase segmentation, combined with other minor editing tools, is the most efficient way to 

properly segment 3D volumes obtained from the NeXT device

• The structure of the GRA Chondrite shows metal lodes and chondrules primarily on 

one side, which supports the theory it was impacted by shock metamorphism

• The segmentation of the EET Howardite reveals how rock from the different layers of 

the Vesta asteroid combined to form this complex structure
Acknowledgments

I would like to thank:

• The SHIP program

• CHRNS

• Neutron Imaging Group

• Jacob LaManna