Symbol or Abbreviation	Unit	Explanation
a, b, c	-	Line parameters in an image
A	pixels	Particle area
CAN	-	Calcium Ammonium-Nitrate fertilizer
Cd	-	Drag coefficient
CEMIB	-	CEmagref Mineral Bench
Cov		Covariance
CV	%	Coefficient of variation
D	m	Particle diameter
f	pixels	Lens focal length
g	m s−2	Gravitational acceleration
h	m	Height of particle above ground
k	-	Weighting coefficient for matching
I	-	pixel intensity value
m	pixels	Image moment
M	kg	Particle mass
NUE	-	Nitrogen Use Efficiency
p	pixels	Particle perimeter
P	m	Particle position
px	-	Pixels
Re	-	Reynolds number
s	-	Scale factor
SCS	-	Spreader coordinate system
T	-	Transformation matrix (rotation and translation)
u	pixels	Image coordinates in camera image 1
v	pixels	Image coordinates in camera image 2
V	m³	Particle volume
vp	m s−1	Particle velocity
vt	m s−1	Tractor driving speed
WCS	-	World coordinate system
α, β	-	Two spread patterns
$\gamma$	-	Convexity
$\delta$	pixels	Distance to epipolar line
$\Delta$t	s	Time between subsequent flashes
$ℇ$	-	Stereomatching coefficient
$\zeta$	-	Time-matching coefficient
$\eta$	-	Circularity
$\mu$	kg m−1 s−1	Air dynamic viscosity
$\rho$	-	Pearson coefficient of correlation
${\rho }_{air}$	kg m−3	Air density
${\rho }_p$	kg m−3	Particle true density
$\sigma$		Standard deviation
$\varphi$	-	Sphericity