Automatic Detection and Classification of Rock Microstructures through
Machine Learning
Abstract
Geologists need help classifying microscope rock images of sigma clasts;
a type of mantled porphyroclasts widely used as kinematic indicators in
rocks. Knowledge about the shear sense of sigma clast during formation
(either CCW or CW shearing) gives insights into rock formation history.
This work reports on early investigation of machine learning techniques
for automatic detection and classification of sigma clasts and their
rotation from photomicrographs. Convolutional Neural Networks (CNNs) are
used to extract and leverage defining features of sigma clasts, such as
shape, color, texture, and tail direction to improve accuracy. We
leverage existing models that are pre-trained on very large collections
of images, and use transfer learning techniques to apply them to
microstructure images. We used YOLOv3 to identify different sigma clasts
in a given image. We also experimented with other large pre-trained
models such as ResNet50, VGG19, InceptionV3 with two additional layers
trained specifically on our dataset. In order to facilitate exploration
of different models with different settings, we are developing a
computational experimentation environment to visualize different CNN
network layers, classification heatmaps, and comparative metrics.
Finally, since models perform better when more data are available, we
are developing a web application to collect additional data from
geoscientists and incentivize their participation in open science. The
website allows researchers to upload images of rock microstructures,
showing them the classification of the images based on the best models
available, and allows them to correct any errors which can be used to
improve the models.