Frontiers in Fuels Science:
Species-Specific Crown Profiles Models from
Terrestrial Laser Scanning
Key Concepts:
 Document accuracy and validity of existing crown biomass equations
 Develop new crown biomass/fuel equations for inland northwest tree
species (Affleck)
 Parameterize crown fuel density profiles over individual stems per species
with TLS
• Stem dimensions
• Crown characteristics (e.g. shape and density)
Where We’ve Come From:
 Branch Scale Biomass Using TLS
Background: Working Hypotheses (TLS)
 Boles
• Incremental bole diameters used to generate basal area
• Diameters could be used predict biomass from revised allometries
 Crown profiles differ between species
• A large body of previous work on crown shapes
• Laser gives precise measurements and characterize crown
• High replication using laser
• Tests using limited sample sizes suggest between species differences
are more pronounced than those within species
 Biomass is distributed unequally throughout a crown:
• Both vertically and horizontally
• Distribution differs between species
Introduction: Sampling
 Connection to Destructive
• Collect TLS data of
sampled trees
• Collect independent
samples concurrently
− same species
− site conditions
Vicinity Map
 TLS Sampling Objective
• n > 200
Trees sampled
Trees & TLS sampled
Introduction: TLS Instrument
Optech Ilris 36D HD
Terrestrial Lidar System
• 10 KHz sampling
• Point density 1cm or less
• Local characterization
Introduction: TLS Sampling
Current Thinking:
Zone of
 Literature suggests that estimating
biomass from TLS requires:
• Scanning from multiple angles
• High resolution
• Offsetting potential occlusion of
data within tree
Project Approach:
 This project seeks to optimize TLS
collection by:
• Limit scanning time by only sampling a
• Control errors of omission through
sampling volume
Zone of
Introduction: TLS Sampling
Data Resolution a Function of
 The instrument is parameterized to
collect data at a set resolution at a
determined range (focal plane)
 Characterize hull of tree
Focal Plane
(~4.0mm density)
 Data decreases in density as it
gains range
Types of Occlusion:
 Penetration of energy through the
canopy or objects
• Angle independent/dependent
 Shadowing of canopy elements
• Depends canopy density
• Angularity (branches shadowing
objects above)
Methods: TLS Collection and Processing
Data Process Flow
 Data Collection
• Largest time commitment (e.g. travel, set up, Etc.)
• ~15 minutes per scan
• Dependent on site conditions (e.g. adjacent tree
 Alignment of Scans (Polyworks)
• Potentially time consuming
 Process Using Lab Developed Applications
• Designed to begin optimizing tree processing for
efficiency and repeatability
• Single processing flow for applying alignment,
calculating bole dimensions, and normalized
canopy distance from
Methods: TLS-Based Bole Measurements
Three Estimates of
Bole Diameter Up The
Three samples of distance
from bole centroid
Fitted line from selected
bole points
Modeled from the initial
bole diameter at the
bottom of the tree
Methods: Distance and Tree Cleaning
Height (m)
Methods: Building a Library of Crown Shapes
Distance (m)
• Species used in preliminary work
• Crown Characterization
• Crown Shapes (profiles and lengths)
• Biomass Distribution
• Bole characterization
• Integrating it all
• What’s next?
• Data sample for preliminary analysis
• 6 Douglas firs (Pseudosuga mensiesii)
• 3 grand firs (Abies grandis)
• 1 ponderosa pine (Pinus ponderosa)
• 1 western larch (Larix occidenatlis)
Analysis: Crown Profiles
• 90th crown width percentile
chosen to define outer hull
• Points at each height interval
Analysis: Crown Profiles
• Rescaled
both axes
as 0-1
• Did this for
6 Douglas
firs and 3
grand firs
Analysis: Crown Profiles
• Combined
all samples
per species
into one
Analysis: Crown Profiles
Model Fitting
• curve smoothing
• scale of variability
• exclusion of
bole/incorporation of
crown base height
Analysis: Crown Profiles
Douglas Fir (n=6)
Grand Fir (n=3)
Ponderosa Pine (n=1)
Western Larch (n=1)
Analysis: Crown Base Height
Using some
impartial metric to
consistently define
lower bound of
crown length
Analysis: Crown Base Height
Analysis: Crown Base Height / Crown Profiles
Analysis: Crown Biomass Distribution
• Hull / void
• Survivability analysis
• Hull delineation
• Within-hull biomass
Analysis: Boles
• Many different radius measures generated
Analysis: Boles
Potential use in linking
TLS data to allometry for
biomass prediction
Problems to overcome
Analysis: Integrating It All
Per Species
Apply crown base metric
Generate the “uber-tree”
Fit crown profile curve
Determine hull-void
Determine biomass
allocation pattern
 For New Trees
• Need species, DBH,
height, crown length
• Use DBH to calculate
• Use crown profile
function to build outer
hull shape
• Allocate biomass within
defined hull
Analysis: Where To Next…
Things to think about:
• Occlusions (of bole, inner vegetation)
• Best metric for CBH delineation
• Appropriate scale of variation for crown profile
• Defining hull/void demarcation
• Distributing biomass within that hull
Next (this summer through Spring 2013)
• More trees, more scanning, more data processing
• Linkages to Affleck lab measures
• Exploration of applications beyond fire
The Laser Team:
 Eric Rowell, Ph.D. Plot scale surface fuels
characterization; integration of airborne and
terrestrial scanning, fuel consumption.
 Tara Umphries, M.S. Quantifying fuel dimensions in a
 Jena Ferrarese, M.S. Measuring conifer crown
dimensions and the distribution of biomass within
 Theodore Adams, M.S. Defining/distributing fuel
elements in diffuse shrubs of sagebrush and chamise.
Joint Fire Sciences Program
Inland Northwest Growth and Yield Cooperative
Affleck lab
Active Remote Sensing Lab, National Center for Landscape Fire Analysis

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