tree canopy size and density assessment with a laser scanner
DESCRIPTION
Tree Canopy Size and Density Assessment with a Laser Scanner. Citrus Research and Education Center. Masoud Salyani and J. Brian Wei. 2 nd Workshop on Precision Agriculture for Florida Citrus January 21, 2004. Citrus grove with dead trees and resets. Spray drift. Ultrasonic sensors. - PowerPoint PPT PresentationTRANSCRIPT
Tree Canopy Size and Density
Assessment with a Laser Scanner
Citrus Research and Education Center
Masoud Salyani and J. Brian Wei
2nd Workshop on
Precision Agriculture for Florida Citrus
January 21, 2004
Citrus grove with dead trees and resets
Spray drift
Ultrasonic sensors
Ultrasonic sensors
Ultrasonic sensors
Photocells
Laser sensor
Laser sensor
CREC Laser system in operation
Scanning system principle
Scan profile
Ground
Window start
α
Li1Li2
Dij
Lij
Lij+1
Hs
D
LG
LLij+1
LLij
Window stop
Ө
132.40
βj
βG
βT
I
II
Sensor
LT
Schematic view of a Distance image
i+1+
ΔW
XL
XR
YB
YT
j
j+1
i
Illustrated in next slide
(1,1)
x
y
Pseudo-color image of a tree
Spatial resolution test
A
HIJK
LM
B
A
HIJK
LMB C D E F G
C
D
E
F
G
A
HIJK
LMB C D E F G
Not continuous
Continuous image lines
Distance image for vertical targets (horizontal resolution)
A
HIJK
LM
B
C
D
E
F
G
Not continuous
Continuous
Distance image for horizontal targets (Vertical resolution)
A
HIJK
LMB C D E F G
WhiteBlack
Signal amplitude image for vertical targets
Ground truth of length measurements in three dimensions
0
200
400
600
w1 w2 w3
Manual measurement
Instrument measurement
0
100
200
300
400
D1 D2 D3
Le
ng
th, c
m.
0
200
400
600
H1 H2 H3
Targets
Std. dev.
Manual vs. laser length measurements
Picture of a test tree
Signal amplitude image
Distance image
Inverted distance image
Smoothing of canopy boundary
Figure 2: Scanning illustration and canopy boundary smoothing
Ground
Lij
Lij+1 LLij+1
LLij
Ө
Sensor
Smoothed canopy
Original canopy
Hs
β
D
Deep gap
Shallow gap
Through hole
Peak-link algorithm
0
50
100
150
200
250
0 50 100 150 200
Distance from tree row plane to canopy, cm
Ve
rtic
al
co
ord
ina
te f
rom
to
p o
f im
ag
e,
pix
el
3rd peak-link
Laser incident point
1st peak-link
Tree row plane
2nd peak-link
Distance image – smoothed by peak-link algorithm
D1a
D2a
Ha
Hb
Hd
Hc
Ground
Level
D2c
D1c
D1b
D2b
Tree
Canopy
Manual Volume Measurement
0
10
20
30
40
50
60
70
80
90
100
D1 L1 L2 L3 M1 M2 M3 H1 H2 H3
Tree
Vo
lum
e, m
3
ManualLaser
Manual- and laser-measured volumes
Std. dev.
Canopy volume at different heights of trees
0
10
20
30
40
50
D1 L1 L2 L3 M1 M2 M3 H1 H2 H3
Tree
Vo
lum
e, m
3
Top 1/3
Middle 1/3
Bottom 1/3
Visual vs. laser-measured densities
0
10
20
30
40
50
60
70
80
90
100
D1 L1 L2 L3 M1 M2 M3 H1 H2 H3
Tree
Fo
lia
ge
de
ns
ity
, %
0
1000
2000
3000
4000
5000
6000
7000
8000
9000
10000
Pix
el/
vo
lum
e r
ati
o,
pix
el/
m3
Visual assessment
Laser- Foliage/canopy volume ratio
Laser- Pixel/volume ratio
yB = 1484.3x - 11237
RB2 = 0.74
yA = 0.808x + 10.582
RA2 = 0.96
0
10
20
30
40
50
60
70
80
90
100
0 10 20 30 40 50 60 70 80 90 100
Visual density assessment, %
La
ser
me
asu
rem
en
t, %
0
1000
2000
3000
4000
5000
6000
7000
8000
9000
10000
Pix
el-
volu
me
ra
tio,
pix
el/m
3
Corr. bet. Visual and laser-measured densities
0
10
20
30
40
50
60
70
80
90
D1 L1 L2 L3 M1 M2 M3 H1 H2 H3
Tree
Fol
iag
e D
ensi
ty, %
South
North
Overall
Foliage density at north and south sides of trees
Std. dev.
Foliage density at different tree heights
0
10
20
30
40
50
60
70
80
90
100
D1 L1 L2 L3 M1 M2 M3 H1 H2 H3
Tree
Fo
liag
e d
ensi
ty, %
Top 1/3Middle 1/3Bottom 1/3
User Interface
Amplitude image of one row
Processed canopy image of the row
Real-time measurements of one row
Real-time run, 1 mph
Real-time run, 3 mph
Thankyou