scene was calculated. Actual size of an image with 640 x 480 pixels corresponded to an
imaging scene of 1.67 m (5.5 ft) long and 1.26 m (4. 12) ft high. As the average size of a
fruit from each plot was known, area of a fruit in a plot was calculated in terms of pixels.
Then, the number of fruits in a plot was determined from the total number of citrus
pixels/plot using the following estimation, and was used to estimate the number of fruits
in a plot. Since
640 x 480 pixel2 = 1.67 x 1.26 m2 = 2.1 m2 = 2107970 mm2
Thus, 1 mm2 = 0.15 pixel2
Let D be an average diameter of a fruit in a plot, Aactual be an area of fruit in two-
dimensional plane, and Armage be an area of fruit in an image, and Tbe total number of
citrus pixels in a plot, then
Aactal K and
A-mage= 0.\"15atl
T T T
Thus, Nfruits-plxels
mage, O.Sactual (\2
Since T (from the image processing algorithm) and D (from the actual harvesting data)
are known, NPfruits-plxels can be obtained.
3.8 Yield Prediction Model
Citrus yield is calculated as number of citrus fruits per unit area. The distances
between citrus trees in the grove were 3.05 m (10 ft) in-row and 6.1 m (20 ft) between-
rows. For this particular experimental setup, yield is calculated as
NP
YE frults- pixels
3.05 x 6.1l(m2) X 2 (trees)