To identify fruits on the tree and determine their locations are the key to harvest fruits by robots. The main features and applications of infrared thermal imaging were reviewed, and main methods to locate fruits on trees were compared. As the low identification rate of common machine vision system, a new method to identify the citrus in a tree canopy by means of infrared thermal imaging was put forward. About 45 infrared thermal images of citrus on trees were acquired from the citrus orchard. It was found that the different thermal distribution among citrus, leaves and branches was about 1^°C and these differences clearly appeared in the gray-level image, which could be easily used to segment the citrus from other parts in the image by using binary image at T=190. A multilayer-masks edge operator was used to extract edge of the image. The results indicated that it was possible to identify citrus on trees using infrared thermal imaging, and it was much easier than the methods presently used.

Date Published: 30 March 2004
PDF: 7 pages
Proc. SPIE 5271, Monitoring Food Safety, Agriculture, and Plant Health, (30 March 2004); doi: 10.1117/12.516018

Published in SPIE Proceedings Vol. 5271:
Monitoring Food Safety, Agriculture, and Plant Health
George E. Meyer; Yud-Ren Chen; Shu-I Tu; Bent S. Bennedsen; Andre G. Senecal, Editor(s)