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. 2021 May 31;21(11):3813.
doi: 10.3390/s21113813.

Orchard Mapping with Deep Learning Semantic Segmentation

Affiliations

Orchard Mapping with Deep Learning Semantic Segmentation

Athanasios Anagnostis et al. Sensors (Basel). .

Abstract

This study aimed to propose an approach for orchard trees segmentation using aerial images based on a deep learning convolutional neural network variant, namely the U-net network. The purpose was the automated detection and localization of the canopy of orchard trees under various conditions (i.e., different seasons, different tree ages, different levels of weed coverage). The implemented dataset was composed of images from three different walnut orchards. The achieved variability of the dataset resulted in obtaining images that fell under seven different use cases. The best-trained model achieved 91%, 90%, and 87% accuracy for training, validation, and testing, respectively. The trained model was also tested on never-before-seen orthomosaic images or orchards based on two methods (oversampling and undersampling) in order to tackle issues with out-of-the-field boundary transparent pixels from the image. Even though the training dataset did not contain orthomosaic images, it achieved performance levels that reached up to 99%, demonstrating the robustness of the proposed approach.

Keywords: computer vision; deep learning; orchard mapping; orthomosaic; precision agriculture; semantic segmentation.

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Conflict of interest statement

The authors declare no conflict of interest.

Figures

Figure 1
Figure 1
Architecture of the modified U-net network implemented in the approach.
Figure 2
Figure 2
Process flow of the proposed methodology for creating segmentation predictions. FN: false negative; FP: false positive.
Figure 3
Figure 3
Channel deconstructing of (a) RGB, (b) HSV, and (c) fused images.
Figure 4
Figure 4
Image color transformations used in the study: (a) RGB image, (b) EQ image, (c) CLAHE image, (d) HSV colorspace image, (e) 6-channel RGB and HSV fused image, and (f) 6-channel CLAHE and HSV fused image.
Figure 4
Figure 4
Image color transformations used in the study: (a) RGB image, (b) EQ image, (c) CLAHE image, (d) HSV colorspace image, (e) 6-channel RGB and HSV fused image, and (f) 6-channel CLAHE and HSV fused image.
Figure 5
Figure 5
Learning plot with training and validation accuracy.
Figure 6
Figure 6
Examples of false positive and false negative segmentation predicted by the developed system (left) as compared to the real segmentation (right).
Figure 7
Figure 7
Results of indicative RGB images covering a range of different conditions.
Figure 8
Figure 8
Undersampled orthomosaic of an orchard with large- to medium-sized canopies (left) and the segmentation predicted by the model (right).
Figure 9
Figure 9
Undersampled orthomosaic of an orchard with young trees featuring small-sized canopies (left) and the segmentation predicted by the model (right).
Figure 10
Figure 10
Undersampled orthomosaic of an orchard with small canopies, not treated for weeds (left), and the segmentation predicted by the model (right).
Figure 11
Figure 11
Complete orthomosaic of a study orchard with trees with small-sized canopies, not treated for weeds (left), and the segmentation predicted by the model (right).

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