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In-Orchard Sizing of Mango Fruit: 1. Comparison of Machine Vision Based Methods for On-The-Go Estimation

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posted on 2024-04-08, 06:31 authored by Chiranjivi NeupaneChiranjivi Neupane, Anand KoiralaAnand Koirala, Kerry WalshKerry Walsh
Estimation of fruit size on-tree is useful for yield estimation, harvest timing and market planning. Automation of measurement of fruit size on-tree is possible using RGB-depth (RGB-D) cameras, if partly occluded fruit can be removed from consideration. An RGB-D Time of Flight camera was used in an imaging system that can be driven through an orchard. Three approaches were compared, being: (i) refined bounding box dimensions of a YOLO object detector; (ii) bounding box dimensions of an instance segmentation model (Mask R-CNN) applied to canopy images, and (iii) instance segmentation applied to extracted bounding boxes from a YOLO detection model. YOLO versions 3, 4 and 7 and their tiny variants were compared to an in-house variant, MangoYOLO, for this application, with YOLO v4-tiny adopted. Criteria developed to exclude occluded fruit by filtering based on depth, mask size, ellipse to mask area ratio and difference between refined bounding box height and ellipse major axis. The lowest root mean square error (RMSE) of 4.7 mm and 5.1 mm on the lineal length dimensions of a population (n = 104) of Honey Gold and Keitt varieties of mango fruit, respectively, and the lowest fruit exclusion rate was achieved using method (ii), while the RMSE on estimated fruit weight was 113 g on a population weight range between 180 and 1130 g. An example use is provided, with the method applied to video of an orchard row to produce a weight frequency distribution related to packing tray size.

Funding

Category 3 - Industry and Other Research Income

History

Volume

8

Issue

12

Start Page

1

End Page

17

Number of Pages

17

eISSN

2311-7524

Publisher

MDPI AG

Additional Rights

CC BY

Language

en

Peer Reviewed

  • Yes

Open Access

  • Yes

Acceptance Date

2022-11-29

Author Research Institute

  • Institute for Future Farming Systems

Era Eligible

  • Yes

Journal

Horticulturae

Article Number

ARTN 1223

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