A COMPUTER-ASSISTED TREE-RING CHRONOLOGY COMPOSITION SYSTEM System Overview By: James B. Engle Department of Electrical and Computer Engineering at The University of Arizona

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A COMPUTER-ASSISTEDTREE-RING CHRONOLOGYCOMPOSITI
ON SYSTEMSystem Overview By James B. Engle
Department of Electrical and Computer
EngineeringatThe University of Arizona
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• Table of ContentsSection Slides1. Background
  - TREES program overview........................ 3
  -62. Introducing the CROSSDATE
  program........................... 7-103.
  Correlation Tool..................................
  ............................. 12-144.
  Composition Tool..................................
  ........................... 15-185. Check
  Tool..............................................
  ......................... 19-226. User
  Help..............................................
  ........................... 237. Contribution
  to Dendrochronology...............................
  .... 24

Reference Engle, James B., A Computer-Assisted
Tree-Ring Chronology Composition System, Masters
Thesis, University of Arizona, 2000.
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• TREES Computer vision based tree-ring
  analysis and measurement system.
• Tree-ring Sample Image Acquisition
• Tree-ring Detection and Measurement
• Tree-ring Width Standardization
• Focus is on a single tree-ring sample.

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• TREESSystem Components

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A Computer-Assisted Tree-RingChronology
Composition System

• TREESGraphic UserInterface

Tree-Ring Views Skeleton Plot
SequentialProcess Steps1. Capture Frames2.
Create Mosaic3. Find Rings4. Measure Rings5.
Create Skeleton Plot
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• TREES Program OutputIndex Value Time Series
• Standardization is the process of modeling and
  removing non-climatic variation to reduce
  absolute tree-ring width measurements to a common
  relative scale.
• Raw tree-ring width measurements are detrended to
  produce index values.
• Index values represent relative variations in
  growth and are the basis of comparing one
  samples growth to another.

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• CROSSDATE A Computer-Assisted Tree-Ring
  Chronology Composition System
• Separate application from TREES.
• Output of TREES is input to CROSSDATE.
• Works simultaneously with TREES.
• Focus is on multiple tree-ring samples.
• A tool, not an expert system.

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• Objectives
• CROSSDATE is a software tool to assist
  dendrochronologists to

• Determine the dating of a tree-ring sample.
• Compose a master chronology for a site from
  individual samples.
• Perform a QC Check to ensure the validity of a
  master chronology.

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• Requirements
• Ability to determine, manually and with computer
  assistance, the point where two tree ring samples
  match in time.
• Ability to compose master chronologies from
  individual samples and other master chronologies.
  
• Ability to rigorously check a tentative
  chronology for correctness.
• Ability to determine and review the specific
  samples from which a master chronology is
  composed for purposes of returning to the
  original wood sample.

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• Requirements
• Easy to use, intuitive graphic user interface
  (GUI) that mimics the steps a tree-ring scientist
  follows when performing manual crossdating.
• Ability to exchange data (Import/Export) in
  common formats to other tree-ring application
  programs.
• Ability to operate on PC and UNIX workstation
  hardware platforms.
• Ability to operate seamlessly with the TREES
  program.

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• CROSSDATE Graphic User Interface

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• Correlation ToolMatch two (2) standardized
  tree-ring samples in time based on relative
  patterns of variation in growth.
• Procedure1. Calculate correlation
  coefficient (r) for each possible match
  point.2. Convert r to t-statistic for
  hypothesis tests.3. Evaluate the
  significance.4. Rank and display the results.

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• Correlation CoefficientEfficiently computed
  using Fast Fourier Transform (FFT) and One-Pass
  statistical accumulation.

Correlation Coefficient
Statistical Accumulation forStandard
Deviation(Sxx shown, Syy similar)
Cross-Correlation via FFT
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• CROSSDATE Correlation Graph

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• Composition ToolCreates a master chronology from
  individual samples and other master chronologies
  after performing pattern matching.
• Definition A master chronology is a composite
  of individual samples. Composite means the
  arithmetic average of component samples index
  values for each year of the entire time period
  range.

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• Master Chronology
• Useful for recording the growth pattern variation
  for a site over some time period.
• Subsequently useful for dating new samples using
  correlation pattern matching.
• International Tree Ring Data Bank (ITRDB)
  provides a simple format for data exchange.
  CROSSDATE imports and exports ITRDB format
  chronology files.
• The annual average index value and number of
  component samples are exchanged with other
  programs.

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• CROSSDATE Master Chronologies

Composedhierarchicallyusingintermediatechronol
ogies.
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• CROSSDATE Master Chronology Display Screen

Sample Depth Components
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• Check ToolPerforms extensive checking on each
  sample component of a master chronology.
• Checks performed1. Date Alignment2. File
  Date Check3. Statistical Outliers4. Overall
  Fit5. Segment Fit
• Results are available on Graphic Display and as a
  Text Report.

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• Component QC Check Panel (Graphic Display)

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• Component QC Check Report (Text Report)

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• Component QC Check Report (Text Report)

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• CROSSDATE User Help

• HTML User Help Files are distributed with
  CROSSDATE.
• Menu button invokes Netscape browser with
  CROSSDATE help index.
• User Help Files may be viewed with any HTML
  viewer.

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• Conclusion

• Contributions to Dendrochronology
• Graphic framework for performing tree-ring sample
  comparison activities.
• Uses familiar methods.
• Completes the TREES system.
• May be extended as new methods are developed.