Principal point (PP)
the geometric center of the image
Conjugate Principle point (CPP)
the principle point of image B on image A in a photo series
RF
Representative fraction
Focal length
distance to the focal plane from the lens inside a camera
Focal length and flying height ratio for scale
RF=f/H
Common focal length
6" or 152.598 mm
Nadir
the point directly below the sensor
Elevation at Nadir
the distance from sea level to the nadir on the ground
Find the scale with this info:
Flight altitude = 3048m
Elevation at Nadir = 259m
Focal Length = 15.2cm
RF = (15.2cm) / (3048m-259m) x 100
RF = 15.2 / 278,900
RF = 1 : 18,348
Photo and ground distance ratio for scale
RF = PD/GD
Equation to derive flying Height (H)
H = Flight Altitude - Elevation at Nadir
Equation to find object height where relief displacement is clear. what are all the variables?
h = (d x H) / r
r is distance from the principle point
h is building height
H is flying height
d is the building height in the image
Equation to find object height where relief displacement isn't clear.
tana = height/length
Relief displacement
causes tall objects to lean away from the center of the image towards the edges of the photo
Wein's Law
the peak wavelength of radiation emission is inversely related to the temperature of an object. (hotter objects emit shorter wavelengths)
Stefan Boltzmann Constant
In a black body, the total intensity of radiation emitted increases across wavelengths
Planck's Law
hotter objects emit more light and brighter
Visible light spectrum
0.38-0.7 μm