DART: Technical Overview
Dendro Analysis & Reporting Tool
A specialized desktop workbench for the manual annotation and quantitative analysis of high-resolution tree-ring imagery. Designed to replace traditional manual measuring with a caliper, it provides a precise digital environment for “on-screen” dendrochronology, handling multi-gigabyte archival scans that exceed the practical limits of many standard image viewers.
Notice · Beta
DART is currently in Beta. While the core measurement engine has been validated against traditional stage micrometers, all analysis outputs should be considered provisional and independently verified before publication or decision-critical use.
System Requirements: Tested on Windows 10/11 and macOS (Apple Silicon / Intel). Minimum 8 GB RAM; 16 GB+ recommended for large Deep Zoom datasets.
Capabilities
BigTIFF Support
Smooth panning and zoom on full-resolution core scans, built on Sharp (libvips) so multi-gigabyte files never load into memory in full.
Deep Zoom Rendering
An OpenSeadragon tiling pipeline serves Deep Zoom Image (DZI) tiles for fluid 60 fps navigation across archival-resolution imagery.
Sub-Pixel Calibration
A 2-point calibration system with DPI-based scaling translates screen interactions into precise physical measurements (microns).
Vector Annotation
Define geometric paths and discrete ring boundaries on a non-destructive Fabric.js vector overlay that never alters the source scan.
Visual Quality Control
Real-time visual feedback on ring counts and inter-ring segment widths supports careful, auditable measurement.
Standard Exports
Export ring-width series to Tucson (RWL) and CSV for downstream use in established crossdating and chronology toolchains.
Core Architecture: High-Performance Visualization
- BigTIFF Handling: Built on Sharp (libvips) to process multi-gigabyte archival scans without loading the full image into memory.
- Deep Zoom Rendering: Utilizes an OpenSeadragon pipeline to dynamically serve Deep Zoom Image (DZI) tiles, ensuring smooth panning and zooming.
- Coordinate System: Implements a sub-pixel coordinate mapping system that translates screen interactions into precise physical measurements.
Digital Analysis Workbench
DART facilitates a strictly manual analysis workflow with computer-assisted precision:
- Vector Annotation: Users define geometric paths and discrete points using a non-destructive Fabric.js vector overlay layer.
- Interactive Calibration: A 2-point calibration system and DPI-based scaling ensure measurement accuracy across different scanning hardware.
- Visual QC: Provides real-time visual feedback on ring counts and segment widths so errors are caught at the point of measurement.
Workflow
- Import scan. Open a TIFF or BigTIFF core scan; DART tiles it for Deep Zoom without loading the full file into memory.
- Calibrate. Set scale with the 2-point calibration tool or enter the scanning DPI so on-screen distances map to physical units.
- Annotate & measure. Mark ring boundaries along a path on the vector overlay; counts and inter-ring widths update in real time.
- Review & export. Visually QC the series, then export to Tucson (RWL) or CSV for downstream analysis.
Reproducibility
All processing is performed locally with no cloud dependencies. Given the same source scan, calibration values, and software version, DART’s geometry computations are deterministic. Measurement outputs nonetheless reflect operator decisions during annotation — document the software version and dataset identifiers in any derived work.
Methods & References
DART is a measurement and reporting environment; it does not impose a statistical model on your data. Exported series are intended to feed established dendrochronological methods and toolchains:
- Tucson / Decadal (RWL) format — interoperable with COFECHA, ARSTAN, and the dplR package for R.
- Gleichläufigkeit (GLK) — Eckstein & Bauch (1969).
- t-values — Baillie & Pilcher (1973); Hollstein (1980).
- Expressed Population Signal (EPS) — Wigley, Briffa & Jones (1984).
Reference links and DOIs to be finalized.
Technology Stack
Download
Download links, version number, and release date to be provided. See the repository for release notes and changelog.
How to Cite
When DART is used in analysis, exports, or figure generation, cite the tool separately in addition to any dataset citations.
@software{dart2026,
title = {DART: Dendro Analysis and Reporting Tool},
author = {{Iowa Forestry Media Library}},
year = {2026},
version = {Beta},
url = {https://iowaforestrymedialibrary.org/dart.html}
}
Questions about DART? Contact the library maintainer at [email protected]. See also the companion tool DART: ChipLab for woodchip geometry and species classification.