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Journal of Zhejiang University (Agriculture and Life Sciences)  2021, Vol. 47 Issue (4): 451-463    DOI: 10.3785/j.issn.1008-9209.2021.03.121
Special Topic: Crop Phenotyping Technologies and Applications     
Maize tassel segmentation based on deep learning method and RGB image
Xun YU1,2(),Zhe WANG1,Haitao JING1(),Xiuliang JIN2(),Chenwei NIE2,Yi BAI2,Zheng WANG3
1.School of Surveying and Land Information Engineering, Henan Polytechnic University, Jiaozuo 454000, Henan, China
2.Institute of Crop Sciences, Chinese Academy of Agricultural Sciences, Beijing 100081, China
3.College of Energy, Chengdu University of Technology, Chengdu 610059, China
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Abstract  

This study focuses on the accuracy and stability of deep learning method for maize tassel segmentation at different tasseling stages and varieties. The RGB images were collected in the experimental base of Chinese Academy of Agricultural Sciences in Xinxiang City of Henan Province from July to September in 2019, and four models, PspNet, DeepLab V3+, SegNet and U-Net, based on the lightweight network as the feature extraction layer, were applied to compare the accuracy of different models for maize tassel segmentation. Then, the U-Net model with the best segmentation accuracy (mIoU=0.780) was selected to segment the maize tassel in different varieties at different tasseling stages. The results showed that the accuracy of U-Net model at different tasseling stages was generally better (mIoU=0.703 to 0.798), and the segmentation accuracy of maize tassel in fully emerged tassel stage was the highest (mIoU=0.798); the segmentation accuracy of maize tassel in different varieties was significantly different, but the average segmentation accuracy of maize tassel for all varieties was higher (mIoU=0.749), and the segmentation accuracy of Zhengdan 958 (ZD958) was the highest (mIoU=0.814). In summary, the U-Net model has good universality and robustness for maize tassel segmentation, which provides an effective method for tassel monitoring in maize phenotypic test in the future.



Key wordsRGB image      deep learning      feature extraction layer      maize tassel      segmentation     
Received: 12 March 2021      Published: 02 September 2021
CLC:  TP 75  
Corresponding Authors: Haitao JING,Xiuliang JIN     E-mail: 211804020012@home.hpu.edu.cn;jht@hpu.edu.cn;jinxiuliang@caas.cn
Cite this article:

Xun YU,Zhe WANG,Haitao JING,Xiuliang JIN,Chenwei NIE,Yi BAI,Zheng WANG. Maize tassel segmentation based on deep learning method and RGB image. Journal of Zhejiang University (Agriculture and Life Sciences), 2021, 47(4): 451-463.

URL:

http://www.zjujournals.com/agr/10.3785/j.issn.1008-9209.2021.03.121     OR     http://www.zjujournals.com/agr/Y2021/V47/I4/451


基于深度学习方法和RGB影像的玉米雄穗分割

为检验深度学习方法对不同品种玉米雄穗在不同生育时期的分割精度和稳定性,利用2019年7月—9月于河南省新乡市中国农业科学院试验基地内采集的RGB影像,通过构建以轻量级网络为特征提取层的PspNet、DeepLab V3+、SegNet和U-Net 4种模型,比较不同模型对玉米雄穗分割精度的差异。结果显示:U-Net模型对不同生育时期玉米品种的雄穗分割精度最高(mIoU=0.780)。该模型在玉米雄穗不同生长阶段的分割精度总体上较好(mIoU=0.703~0.798),其中在完全抽雄期的分割精度最高(mIoU=0.798);U-Net模型对不同玉米品种的雄穗分割精度差异明显,但对所有玉米品种雄穗的平均分割精度较高(mIoU=0.749),其中对郑单958(ZD958)的分割精度最高(mIoU=0.814)。表明U-Net模型对玉米雄穗分割具有较好的普适性与鲁棒性,为今后玉米表型试验中对雄穗的监测提供了一种有效的方法。


关键词: RGB影像,  深度学习,  特征提取层,  玉米雄穗,  分割 
Fig. 1 Ground image acquisition scene and equipmentA. Scene of image acquisition in the field; B. Sony DSC-RX0M2 digital camera; C. Suspender.

数据集

Dataset

模型

Model

特征提取层

Feature

extraction layer

分辨率

Resolution/

mm

影像大小

Image size

轮次

Epoch

学习率

Learning

rate

批量

大小

Batch

size

训练集数量

Number of

train set

验证集数量

Number of

validation

set

全生育时期1)

Whole tasseling stage1)

PspNetMobileNet0.564 800×3 200500.0012510219
DeepLab V3+MobileNet V20.564 800×3 200500.000 14510219
SegNetMobileNet0.564 800×3 200500.000 14510219
U-NetMobileNet0.564 800×3 200500.0012510219

完全抽雄期

Fully emerged tassel stage

U-NetMobileNet0.564 800×3 200500.0012416179

未完全抽雄期

Partially-tasseling stage

U-NetMobileNet0.564 800×3 200500.00129341
HT1U-NetMobileNet0.564 800×3 200500.00126331
FK139U-NetMobileNet0.564 800×3 200500.00126235
DK517U-NetMobileNet0.564 800×3 200500.00126818
JNK728U-NetMobileNet0.564 800×3 200500.00126126
XY335U-NetMobileNet0.564 800×3 200500.00124916
ZD958U-NetMobileNet0.564 800×3 200500.00127221
ZY8911U-NetMobileNet0.564 800×3 200500.00126427
DK653U-NetMobileNet0.564 800×3 200500.00125324
Table 1 Characteristics of the several datasets used in this study
Fig. 2 Examples of image division of different growth stagesA. Image of maize tassel at the partially-tasseling stage; B. Image of maize tassel at the fully emerged tassel stage.
Fig. 3 Examples of using the Labelme software to label image of maize tassel
Fig. 4 Network framework of SegNet model
Fig. 5 Network framework of PspNet model
Fig. 6 Network framework of DeepLab V3+ model
Fig. 7 Network framework of U-Net model

类型/步长

Type/stride

卷积核形状

Convolution kernel shape

输入大小

Input size

Conv/s23×3×3×32224×224×3
Conv dw/s13×3×32 dw112×112×32
Conv/s11×1×32×64112×112×32
Conv dw/s23×3×364 dw112×112×64
Conv/s11×1×64×12856×56×64
Conv dw/s13×3×128 dw56×56×128
Conv/s11×1×128×12856×56×128
Conv dw/s23×3×128 dw56×56×128
Conv/s11×1×128×12828×28×128
Conv dw/s13×3×128 dw28×28×256
Conv/s11×1×128×25628×28×256
Conv dw/s23×3×256 dw28×28×256
Conv/s11×1×256×51214×14×256
5×Conv dw/s13×3×512 dw14×14×512
5×Conv/s11×1×512×51214×14×512
Conv dw/s23×3×512 dw14×14×512
Conv/s11×1×512×1 0247×7×512
Conv dw/s23×3×1 024 dw7×7×1 024
Conv/s11×1×1 024×1 0247×7×1 024
Avg Pool/s1池化 Pooling 7×77×7×1 024
FC/s11 024×1 0001×1×1 024
Softmax/s1分类器 Classifier1×1×1 000
Table 2 Network structure of MobileNet
Fig. 8 Residual network structure

输入

Input

操作

Operator

tcns
2 242×3conv2d3212
1 122×32bottleneck11611
1 122×16bottleneck62422
562×24bottleneck63232
282×32bottleneck66442
282×64bottleneck69631
142×96bottleneck616032
72×160bottleneck632011
72×320conv2d 1×11 28011
72×1 280avgpool 7×71
1×1×kconv2d 1×1k
Table 3 Network structure of MobileNet V2

混淆矩阵

Confusion matrix

真实值 True value
正例 Positive负例 Negative

预测值

Predicted value

正例 Positive正确分类的正例 True positive (TP)错分成正例的负例 False positive (FP)
负例 Negative错分成负例的正例 False negative (FN)正确分类的负例 True negative (TN)
Table 4 Confusion matrix
Fig. 9 Segmentation result of maize tassel in whole tasseling stage dataset by four different deep learning models

模型

Model

分辨率

Resolution/

mm

影像大小

Image size

训练集/验证集

Train set or

validation

set

召回率

Recall

准确率

Precision

平均交并比

Mean

intersection

over union

每张影像中雄穗像元数精度

Accuracy of tassel pixel

number in each image

R2rRMSE
PspNet0.564 800×3 200训练集 Train set0.1560.4820.5490.530.708 8
0.564 800×3 200验证集 Validation set0.1280.4400.5370.510.755 3
DeepLab V3+0.564 800×3 200训练集Train set0.5360.6880.7040.830.221 3
0.564 800×3 200验证集 Validation set0.4980.6660.6880.790.250 9
SegNet0.564 800×3 200训练集 Train set0.3980.5870.6410.880.388 5
0.564 800×3 200验证集 Validation set0.3330.5150.5430.880.433 8
U-Net0.564 800×3 200训练集 Train set0.7030.7920.7920.850.323 5
0.564 800×3 200验证集 Validation set0.6760.7800.7800.840.332 3
Table 5 Accuracy evaluation of each model based on whole tasseling stage dataset
Fig. 10 Segmentation accuracy of maize tassel at different tasseling stage datasets by U-Net model with MobileNet as feature extraction layerA. Whole tasseling stage; B. Fully emerged tassel stage; C. Partially-tasseling stage.

生育时期

Growth stage

分辨率

Resolution/

mm

影像大小

Image size

训练集/验证集

Train set or

validation set

召回率

Recall

准确率

Precision

平均交并比

Mean

intersection

over union

每张影像中

雄穗像元数精度

Accuracy of tassel

pixel number in

each image

R2rRMSE

全生育时期

Whole tasseling stage

0.564 800×3 200训练集 Train set0.7030.8020.7920.850.323 5
0.564 800×3 200验证集 Validation set0.6760.7920.7800.840.332 3

完全抽雄期

Fully emerged tassel stage

0.564 800×3 200训练集 Train set0.7290.7940.7990.720.318 7
0.564 800×3 200验证集 Validation set0.7290.7930.7980.670.303 7

未完全抽雄期

Partially-tasseling stage

0.564 800×3 200训练集 Train set0.4680.8330.7100.880.210 6
0.564 800×3 200验证集 Validation set0.4600.8090.7030.940.252 6
Table 6 Segmentation accuracy evaluation of datasets at different tasseling stages by U-Net model with MobileNet as feature extraction layer
Fig. 11 Segmentation accuracy of maize tassel in different variety datasets by U-Net model with MobileNet as feature extraction layer

品种

Variety

分辨率

Resolution/

mm

影像大小

Image size

训练集/验证集

Train set or

validation set

召回率

Recall

准确率

Precision

平均交并比

Mean intersection

over union

每张影像中

雄穗像元数精度

Accuracy of tassel pixel number in each image

R2rRMSE
HT10.564 800×3 200训练集 Train set0.6260.8360.7680.870.165 8
0.564 800×3 200验证集 Validation set0.6100.8380.7600.770.183 2
FK1390.564 800×3 200训练集 Train set0.4800.8300.7100.860.207 1
0.564 800×3 200验证集 Validation set0.4390.8200.6910.700.236 9
DK5170.564 800×3 200训练集 Train set0.6410.7860.7600.960.409 4
0.564 800×3 200验证集 Validation set0.5840.7640.7340.980.426 0
JNK7280.564 800×3 200训练集 Train set0.5280.7900.7190.950.223 4
0.564 800×3 200验证集 Validation set0.5210.7740.7140.960.205 7
XY3350.564 800×3 200训练集 Train set0.5900.8350.7550.980.380 2
0.564 800×3 200验证集 Validation set0.5380.8380.7290.990.383 5
ZD9580.564 800×3 200训练集 Train set0.7190.8740.8190.870.225 5
0.564 800×3 200验证集 Validation set0.7180.8830.8140.770.243 1
ZY89110.564 800×3 200训练集 Train set0.6560.8130.8150.960.266 5
0.564 800×3 200验证集 Validation set0.6540.7820.7990.920.276 4
DK6530.564 800×3 200训练集 Train set0.5670.8030.7420.970.423 7
0.564 800×3 200验证集 Validation set0.5810.8860.7480.960.095 1
Table 7 Segmentation accuracy evaluation of variety datasets by U-Net model with MobileNet as feature extraction layer
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