CROSSDATE Application Overview
The CROSSDATE program is an interactive graphic application to aid dendrochronologists in:
The program is the result of cooperative efforts between the Laboratory for Tree-Ring Research (LTRR) and the Digital Image Analysis Laboratory (DIAL) in the Electrical and Computer Engineering Department at the University of Arizona. The research was funded by the National Science Foundation (Grant SBR9601867) and the University of Arizona, Office of the Vice President for Research. A full technical description of the program and its development may be found in:
James B. Engle, A Computer Assisted Tree-Ring Chronology Composition System, Master's Thesis, The University of Arizona, Department of Electrical and Computer Engineering, 2000.
This program complements TREES, a computer vision based tree-ring analysis and dating system. The CROSSDATE program focuses on comparing multiple tree-ring samples for growth pattern matching. The TREES program focuses on tree-ring sample image acquisition and measurement.
The unique contribution of the CROSSDATE program is the graphic framework for performing tree-ring sample comparison activities. The CROSSDATE program implements methods familiar to dendrochronologists for performing the tasks of correlation, composition, and quality control checking in a computer-assisted environment.
Up to three tree-ring samples may be viewed and compared on the basic graphic screen at a time. Tree-ring samples may consist of hundreds of ring width measurements. Matching large samples for dating can be an overwhelming and time-consuming task. The correlation tool provides a quick and effective numeric tool for finding the "best" match position between two tree-ring series. The tool is based on statistical covariance theory and is efficiently implemented using Fast Fourier Transforms (FFT).
Once the samples have been pattern matched in time, a composition tool is provided to create a master chronology from component samples or other chronology files. The three-sample composition limit is bypassed through the use of hierarchical composition. Using a virtual tree data structure for sample components, there is practically no limit to the number of components that may be used to compose a master chronology. The CROSSDATE program imports and exports ITRDB format chronology files.
Dendrochronologists have used program COFECHA for many years as a tool for validating a master chronology from its components. The CROSSDATE program implements most of the functionality of program COFECHA in a highly visual, graphic environment. The fit of a sample component in the master chronology is tested by temporarily removing it from the chronology and checking its correlation with the remainder of the chronology. This is performed for the overall sample versus the overall chronology, as well as 50-year segments of the sample versus the corresponding segment of the master chronology. The master chronology is also checked year-by-year for sample component ring widths that are statistical outliers. The CROSSDATE program additionally performs sample and file date checking for each sample component of the master chronology. The results of all tests are displayed for the user on screen using color to convey the results of each test. The analyst may also produce a text report detailing the results of each sample component test.
Click here for Dendrochronology Software
Click here for COFECHA Program
The CROSSDATE program has been developed for Sun Solaris and Linux operating systems on PC and UNIX Workstation hardware platforms.
Last Updated: June 2000
University of Arizona
Questions and Comments: trees@ece.arizona.edu
Digital Image Analysis Laboratory and
Laboratory for Tree Ring Research © 2000