Digitizing Window EllipseFit is an integrated program for geological finite strain analysis. It is used to derive two and three-dimensional strain from oriented photographs of thin sections, hand samples, or outcrop surfaces, and is designed for laboratory and field based structural geology studies. The intuitive graphical interface and multi-platform deployment also make it ideal for teaching introductory or advanced structural geology laboratories.

Strain Map Images of oriented sections can be digitized using center-point, ellipse, polygon, and filled polygon methods. Polygon fitting, using moment-equivalent ellipses, allows a wide range of geological objects to be analysed, including ooids, pebbles, fossils, and irregular clasts.

Fry Plot Graphical strain analysis techniques include Fry graphs, polar Elliott and Rf/Φ diagrams, strain maps, and a variety of polar and cylindrical hyperboloidal projections with automatic contouring.

Best-fit ellipse calculations include shape-matrix eigenvalue, mean radial length, and hyperboloidal vector mean. Shape-matrix error analysis is done analytically and using bootstrap techniques. The initial data set can be unstrained to check variation in the calculated pre-strain fabric.

Wellman Graph Fitting of ellipse-section data to a best-fit ellipsoid is done using the shape-matrix technique of Shan. Error analysis is done by calculating the section ellipses, and comparing the misfits between calculated and observed section ellipses.

Graphical displays of ellipsoid data include Nadai and Flinn graphs. Data can be directly digitized from photographs, or can be imported using comma or tab delimited spreadsheet files. Graphs can be exported as bitmap images in various formats, or as vector graphics files which can be imported into graphics editing programs, such as Adobe Illustrator.

Nadai Plot EllipseFit was used for teaching strain analysis workshops with Paul Karabinos and Matty Mookerjee at the 2012 Structural Geology and Tectonics Forum, at Williams College, and the 2014 Structural Geology and Tectonics Forum, at the Colorado School of Mines. The newer versions contains additional statistical procedures, progress on the User Manual, tutorial exercises, bug fixes, and new features.

For Windows installation, download the file EllipseFit_3.2.1_Win.zip by clicking on the link above. Right click on the downloaded file, and select the Extract All option to extract the contents. The resulting folder will contain the EllipseFit application, the User Manual, example files, and support files. You may move this folder anywhere you like, including to a thumb drive. The folder Resources must stay in the same folder as the EllipseFit.exe application.

For Macintosh installation download the file EllipseFit_3.2.1_Mac.dmg, double click on it, and drag EllipseFit to your Applications folder. The User Manual, and Example Files folder should be copied to a directory of your choice.

For Linux installation download the file EllipseFit_3.2.1_Lin.tgz, double click on it, and copy the extracted EllipseFit folder, User Manual, and Example Files folder to a directory of your choice.

EllipseFit is written by Frederick W. Vollmer and is free. Please read the accompanying User Manual for information on license, citation and references. EllipseFit is in active development, and your input, bug reports, and suggestions are greatly appreciated.

Elliott Plot Rf Phi Plot