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Adam DickM.Sc.F. Candidate, University of New Brunswick2007 Western Mensurationists MeetingJune 24-26, 2007 Kelowna, B.C.
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April 22, 2023 Adam Dick ~ Western Mensurationists Meeting 2
April 22, 2023 Adam Dick ~ Western Mensurationists Meeting 3
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April 22, 2023 Adam Dick ~ Western Mensurationists Meeting 7
Photography has been an important tool used by foresters for many years
Satellite/ aerial photography underpins most large scale inventories
What if we could have an in-stand perspective to help interpret collected data?
Assist by making data collection more efficient?
April 22, 2023 Adam Dick ~ Western Mensurationists Meeting 8
April 22, 2023 Adam Dick ~ Western Mensurationists Meeting 9
Equipment Digital camera Tripod Tripod mount
Ensures nodal point of lens is above rotational axis of tripod
Eliminates parallax errors
April 22, 2023 Adam Dick ~ Western Mensurationists Meeting 10
Camera mounted vertically
Photo every 15-degrees
24 photos per plot Ensures adequate
overlap between adjacent images
Focus, flash settings the same around plot
April 22, 2023 Adam Dick ~ Western Mensurationists Meeting 11
April 22, 2023 Adam Dick ~ Western Mensurationists Meeting 12
Software (Panorama Factory v4.5) Automates stitching process Automatically corrects barrel distortion,
detects focal length
April 22, 2023 Adam Dick ~ Western Mensurationists Meeting 13
Unwrap and print out flat stand Distortion free Consistent scale
April 22, 2023 Adam Dick ~ Western Mensurationists Meeting 14
So………How can we use these photographs?
April 22, 2023 Adam Dick ~ Western Mensurationists Meeting 15
Using photography
April 22, 2023 Adam Dick ~ Western Mensurationists Meeting 16
To calculate distance to object Dimension of the tree
(or surrogate) And camera focal
length
April 22, 2023 Adam Dick ~ Western Mensurationists Meeting 17
i
DR f
a
Calculate azimuth to object
April 22, 2023 Adam Dick ~ Western Mensurationists Meeting 18
o3600.03 degrees/pixel
12,976
Azimuth of first tree measured used as reference
Could arbitrarily start at zero if only relative position of trees is required
April 22, 2023 Adam Dick ~ Western Mensurationists Meeting 19
Azimuth=7+(1515.59-227.05) 0.03
Using photography
April 22, 2023 Adam Dick ~ Western Mensurationists Meeting 20
Bitterlich 1948 “basal area density of a unit area of area can be
estimated by counting those trees whose diameter at breast height (dbh) subtended angles appearing larger than the horizontal angle-gauge” (Grosenbaugh 1958)
April 22, 2023 Adam Dick ~ Western Mensurationists Meeting 21
G zk
D ak
R b
Using a camera Decourt, N. 1956 Utilisation de la photographie
pour mesurer les surfaces terriers. Revue forestière française, Vol 8. No.7 pp.505-507
Adaptation of Bitterlich to use photographs
April 22, 2023 Adam Dick ~ Western Mensurationists Meeting 22
i
G zk
D a ak
R b f
Several methods identified to do ACS
Measure width of trees in photograph Calculate the BAF of
each tree Apply desired BAF
constant (e.g. mBAF2)
April 22, 2023 Adam Dick ~ Western Mensurationists Meeting 23
22 250 50 50 iD a a
BAFR b f
Calibrate gauge width for photograph
Count trees larger than gauge width
April 22, 2023 Adam Dick ~ Western Mensurationists Meeting 24
min50
i BAF fa
Do as a prism does Shift the tree at
breast height by gauge width
Tree overlaps: in Tree cut: out
April 22, 2023 Adam Dick ~ Western Mensurationists Meeting 25
April 22, 2023 Adam Dick ~ Western Mensurationists Meeting 26
49 plots Sampled trees with a mBAF1 prism 1400 trees sampled▪ Measured tree DBH▪ Distance and azimuth to each tree▪ Took photographs at each plot
April 22, 2023 Adam Dick ~ Western Mensurationists Meeting 27
April 22, 2023 Adam Dick ~ Western Mensurationists Meeting 28
Sampled across range of densities Stand types 2 camera models
Olympus D550Z, 3 megapixels Canon PowerShot SD200, 3.2 megapixels
Stand Density Class (stems/ha)
0 500 1000 1500 2000 2500 3000
Num
ber o
f Plo
ts
0
5
10
15
20
25
30
Azimuth calculations Linear regression
Field measurements vs. measurements from photo
April 22, 2023 Adam Dick ~ Western Mensurationists Meeting 29
April 22, 2023 Adam Dick ~ Western Mensurationists Meeting 30
Distance calculations Linear regression
Field measurements vs. measurements from photo
Photography is underestimating the distance
Azimuth is generally good
Relative positions of the trees is good
Need to adjust the focal length
April 22, 2023 Adam Dick ~ Western Mensurationists Meeting 31
TREE VISIBILITY BY BAF SELECTION
Tree Visibility by BAF selection
mBAF Factor1 2 3 4 5 6
Perc
ent V
isib
le %
0
20
40
60
80
100
120
TREE VISIBILITY BY DISTANCE
Tree Visibility by Distance
Distance from plot centre (m)0 5 10 15 20 25 30 35
Num
ber o
f Tre
es
0
20
40
60
80
100
120
140
160
180
% o
f Tre
es V
isib
le
0
20
40
60
80
100
120
140
160
180
# of trees measured# of trees visiblepercent of tres visible
April 22, 2023 Adam Dick ~ Western Mensurationists Meeting 32
April 22, 2023 Adam Dick ~ Western Mensurationists Meeting 33
BAF calculations Field measurements
vs. measurements from photo
April 22, 2023 Adam Dick ~ Western Mensurationists Meeting 34
Other Applications As a monitoring tool Repeated measures
April 22, 2023 Adam Dick ~ Western Mensurationists Meeting 35
Plot 52 – Pre Harvest
Plot 52 – Post Harvest
Maintain data integrity Prescription training
tool
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