The library serves as a database of all the information the user and the program have identified. Items in the library can be edited in case the user or automatic routines make a mistake, and the entire data set can be imported into Microsoft Excel or other programs for further analysis.

Apatite to Zircon, Inc. specializes in geological dating by apatite and zircon fission track methods. The company has four employees and is located in Viola, Idaho. Companies and universities interested in learning about the geological history of a rock bed can send samples to A2Z for analysis.

Track Finding

Apatite to Zircon, Inc.

2011-2012 Apatite to Zircon Computer Science ClinicAutomated Characterization of Fission

Tracks in Apatite Crystals

Tracks are found as follows:1. Extract straight lines using the

Hough transform2. Extend these lines to determine tip candidates3. Consider all pairs of found tips on either side of

each line4. Select the highest scoring pair

Tracks are scored based on:• edge strength along the line• the contrast and shape scores of its tips• Angle agreement among the tips and the line

Problem Statement

MotivationOne of the most important applications of fission track dating is its role in informing oil exploration and mining operations. However, obtaining any useful information requires many tedious hours of repetitious work in which a geologist locates and measures fission tracks and etch pits. Even automating the simplest portions of these tasks can result in large time-savings, and the geologist’s time can be spent making decisions that require expertise and judgment.

Etch Pit AnalysisAnalyzing the etch pits in a grain provides important information to the geologist about the apatite crystal itself. Etch pits are detected by analyzing the entire image as follows:

1. Threshold to extract foreground features2. Smooth the contours3. Rule out some contours based on size4. Fit ellipses and rule out those with poor ellipse fit5. Choose the largest population of features whose

ellipses are oriented at a similar angle

AcknowledgmentsTeam MembersLeif Gaebler ‘12

Calvin Loncaric ’12 (PM)Colin O’Byrne ‘12Thea Osinski ‘12

A2Z LiaisonRay Donelick, Ph.D.

Faculty AdvisorZachary Dodds

A grain of Apatite (image is 87x66 microns)

One tip of a fission track An etch pit, 1.5 microns long

The goal of this project is to build an application for finding and characterizing fission tracks and fission track tips in apatite grains as autonomously as possible, with the ability for a human user to correct and identify those features as needed or desired. The application will also include a library of results.

User Interface and Deliverables

The team is delivering its system to A2Z with a user interface that encapsulates all of its automatic and human-assistive functionality. The interface can load a stack of images, scroll through them, and interact with the image features using the mouse. Menus and buttons provide access to automated tip-, track-, and etch-pit-finding.

Results:

• Blue lines come from the Hough Transform

• Blue dots are tip hint locations

• Red dots are potential tips

• The green line is the resulting track Results from

automatic etch pit analysis:

• Red features are potential etch pits

• Green features are the best selected etch pits

Data Library

Background Apatite (Ca10(PO4)6[F,Cl,OH,Br]2) is a common mineral compound in both rocks and organisms. Uranium-238 occurs naturally in apatite and has a half-life of 4.468 billion years. When fission events occur in an apatite crystal, a linear track is created. These tracks can be revealed under a microscope following a polishing and acid etching process, and the track characteristics can tell a lot about the crystal’s history. The etching process produces small features called etch pits. Their size and orientation can be used to infer information about the grain composition.

Tip Finding

Poor shape scoreContrast: 0.18

Shape: 0.10

Tips can be located automatically near a hint location. The algorithm works as follows:

1. Threshold to extract foreground features2. Extract smooth contours around features3. Find point of highest curvature4. Fit a parabola to the contour5. Score based on shape and contrast

Good tip scoresContrast: 0.27Shape: 0.98

Wrong Tips

Correct Tip

A geologist identifying fission tracks

Poor contrast scoreContrast: 0.048

Shape: 0.97

Contour Rotated contour with parabolic fit

An apatite crystal