Poster 4
IC3D 2013
Assessment of plant leaf area
measurement by using stereo-vision
Vincent Leemans, Benjamin Dumont, Marie-France
Destain
(Gembloux Agro-Bio Tech, ULg, Belgium)
IC3D 2013; Liège, Belgium; 3-5 Dec 2013
Problem
●
IC3D 2013
Leaf Area Index and Average Leaf Angle are important agronomic
parameters for crop grow monitoring
●
Their measurement is tedious and require a high work load
●
An alternative method should be quicker and present a similar precision
●
2D solution present a saturation problem
Vincent Leemans - Belgium
Poster 4
Solution
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Histogram equalization
●
Images rectification
●
●
●
IC3D 2013
Computation of xyz coordinate of each pixel (“modified H. Hirschmuller
algorithm”)
Image segmentation (Leaves/Soil)
Computation of the areas
AB×⃗
AC∣/2
∑ ∣⃗
● Leaves
triangles
● Total : based on the mean leave z plane
● LAI = Leave Area / Total Area
●
ALA : mean of α
CP=⃗
AB×⃗
AC
CP z
α=acos
∣CP∣
( )
Vincent Leemans - Belgium
A
B C
A B
C D
A B
C D
Poster 4
r = 0.9997
slope = 1.0003
1,8
1,6
True distance (m)
Results
1024
1,4
Regres
(1024)
1,2
1280
Regres
(1280)
1
IC3D 2013
●
Good estimation of the mean distance
●
Over-estimation of the measured area
●
Both for the laboratory and for the filed
tests
0,8
0,8
1
1,2
1,4
1,6
Estimated distance 3D (m)
Image sizes
1,8
1024*768
1280*960
relative (%)
m²
relative
(%)
m²
Accuracy
34
0.0053
49
0.0075
Precision
10.9
0.0017
15.8
0.0024
Vincent Leemans - Belgium
Poster 4
Results
●
●
IC3D 2013
Analysis of the error : 
 estimation of LAI via regression
r= 0.93, LAI= 0.39, similar to manual
measurements
A C
B
Vincent Leemans - Belgium
Poster 4