This program calculates the best-fit anisotropy parameters, and estimates the parameter errors, from a 2-D image or a set of 3-D images (e.g. tomography). For details of the method see: Thissen, C. J., & Brandon, M. T. (2015). An Autocorrelation Method for Three-Dimensional Strain Analysis. Journal of Structural Geology.
For comments, questions, or suggestions, please email cthissen@gmail.com or leave a comment under the issues tab at github.com/cthissen/acf2strain
Christopher J. Thissen, Yale University
Mark T. Brandon, Yale University
Photomicrographs and X-ray tomography provide image data of fabrics. This program finds the parameters that best describe the anisotropy of these images. One example application is to provide quantitative estimates of deformation in geologic samples. The figure below gives one example from the paper, where the anisotropy parameters are the maximum, intermediate, and minimum stretch directions, X, Y and Z, and their magnitudes, Sx, Sy and Sz.
acf2strain requires Matlab 2014 or later.
This program requires the following toolboxes and additional codes:
- Curve Fitting Toolbox.
- Image Processing Toolbox.
- splinefit.m is included with the code, and is also available online at:
http://www.mathworks.com/matlabcentral/fileexchange/13812-splinefit - sort_nat is included with the code, and is also available online at:
http://www.mathworks.com/matlabcentral/fileexchange/10959-sort-nat--natural- order-sort - export_fig is a useful suite of programs for saving publication-quality
figures, and is included with the code. It is also available online at:
http://www.mathworks.com/matlabcentral/fileexchange/23629-export-fig - coolwarm is included with the code.
- cmapscale is included with the code.
This program can be RAM intensive due to the need to store many arrays of equivalent size to the three-dimensional tomogram. I have found that 16GB is sufficient for the examples included here. However, the code can be modified to run on systems with less RAM. Please contact the author for details.
No installation is necessary.
We have included three examples: 1) the undeformed ooids, 2) the 3D phantom, 3) tomogram of sample 92810-3 from the Olympic Mountains. Each sample has a script with the prefix "run_" that can be used to run the strain analysis. For example, to run the strain analysis on the 3D phantom, open the "run_3Dphantom.m" file and push the "run" button, which looks like a green play button.
The required computation time for these examples will vary from computer to computer, but should be on the order of about 10 minutes.
Output is stored in the Results folder, including best-fit deviatoric strain results and goodness of fit parameters. A number of useful images are plotted and saved, such as those found in Thissen and Brandon (2015). If Flag.saveMatFile is set to true, the program will also save a.mat file in the Results folder. If present, this file will be loaded to avoid running the non-linear fitting routine again.
Details of the latest version can be found on the github project page under server project page under https://github.com/cthissen/acf2strain
Christopher Thissen, Yale University. christopher.thissen@yale.edu
Mark Brandon, Yale University. mark.brandon@yale.edu
Your comments are welcome! If you find any bugs or have feature requests report them to Christopher Thissen, christopher.thissen@yale.edu.
Issues can also be reported online: https://github.com/cthissen/Drex-MATLAB/issues
See License file.