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23 NOVEMBER 2014NJFAARHUS
UNIVERSITYAU
ESTIMATING THE CONTENT OF CLOVER AND GRASS IN THE SWARD USING A CONSUMER CAMERA AND IMAGE PROCESSINGA. K. Mortensen1, H. Karstoft1, K. Søegaard2 and R. N. Jørgensen1
1Department of Engineering, Aarhus University2Department of Agroecology, Aarhus University
23 NOVEMBER 2014NJFAARHUS
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OUTLINE
Motivation Test bed and data acquisition Methodology Results Conclusion and future work
23 NOVEMBER 2014NJFAARHUS
UNIVERSITYAU
MOTIVATION
Clover and grass is sown as a catch crop and as a feed crop However, it is unknown how the distribution is in the field The distribution and total dry matter determines
› the N-uptake in the field› As feed for dairy cows
› intake› milk yield
Current method is destructive analysis› Labour intensive› Cumbersome
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TEST BED AND DATA ACQUISITION
Plot experiment (2013) near Research Center Foulum, Denmark Two different seed mixtures:
› “Blanding 35”: perennial ryegrass and white clover › “Blanding 45”: perennial ryegrass, festulolium, red clover and white
clover Photographed and cut on 4 different occasions
› Cuts made within 3 days after photograph› Photographed from above› 45 images› Dry matter analysis in laboratory
› Dry matter: 195 kg/ha 6111 kg/ha› Clover: 10-72%› Grass: 26-90%› Weed: 0-3%
23 NOVEMBER 2014NJFAARHUS
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TEST BED AND DATA ACQUISITION
23 NOVEMBER 2014NJFAARHUS
UNIVERSITYAU
TEST BED AND DATA ACQUISITION
23 NOVEMBER 2014NJFAARHUS
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METHODOLOGY
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METHODOLOGY
Illumination classification Direct and indirect sun
light
Histogram of pixel intensities
Cross correlation used for classification
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METHODOLOGY
Coverage estimation Remove background:
› Soil, dead plant material and deep shadows
Extract clover leafs:› Inverted edge image
+ erosion Grass:
› Remaining Trained on patches
23 NOVEMBER 2014NJFAARHUS
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METHODOLOGY
Transformation of coverage to dry matter distribution
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RESULTS
Coverage estimation
Direct light Indirect light
Sh* So* G* C* F* W* ∑ Sh* So* G* C* F* W* ∑
Sh 66% 1% 25% 8% 0% 0% 295
5
Sh 52% 11% 29% 9% 0% 0% 3934
So 0% 0% 0% 0% 0% 0% 0 So 11% 87% 2% 1% 0% 0% 2422
G 9% 0% 73% 17% 0% 0% 474
5
G 11% 1% 65% 23% 0% 0% 6757
C 13% 0% 39% 48% 0% 0% 656
5
C 3% 0% 29% 68% 0% 0% 1349
1
F 30% 20
%
46% 4% 0% 0% 254 F 18% 0% 77% 5% 0% 0% 79
W 24% 0% 71% 4% 0% 0% 181 W 7% 0% 52% 41% 0% 0% 617
∑* 336
1
98 698
6
425
5
0 0 - ∑* 354
1
265
4
979
5
1131
0
0 0 -
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RESULTS
Dry matter distribution
No correlation between error and mixture, clover dry matter or total dry matter.
Error (%-points) Absolute error (%-points) Mean Std. Max Min Mean Std. Max MinTest set: Clover -2.1 9.8 19.1 -15.6 7.9 5.8 19.1 0.0 Grass 2.6 10.4 17.4 -18.7 8.8 5.7 18.7 1.3Training set: Clover 0.0 12.9 18.9 -50.3 8.6 9.4 50.3 0.2 Grass 0.0 13.5 51.0 -20.7 9.2 9.7 51.0 0.2
23 NOVEMBER 2014NJFAARHUS
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CONCLUSION AND FUTURE WORK
It is possible with a reasonable accuracy (8-9%-points) Greatest source of error
› Coverage estimation Room for improvement
› Better estimation of coverage› Texture analysis
› Illumination invariant model› Include growth models
› Time since last harvest› Temperature sum› Available water
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