Se ni
Mathematical Definitions
Physical Definitions
(Rays):
The straight lines passing through the
projection center.
Principal rays:
The light rays passing through the entran-
cc pupil center.
Principal point H':
The foot of the perpendicular from pro-
jection center O on the image plane.
Principal point H':
The point of penetration of that principal
ray through the image plane whose object-
side part, if linearly extended, is perpen-
dicular to the image plane.
In the case of rotation symmetry, this
definition supplies the center of sym-
metry in the image plane, in the case of
freedom from distortion, the definition
furnishes the base point of the perpendicu-
lar from the projection center on the
image plane (corresponding to the ma-
thematical definition).
The frame fiducial marks of the photo-
grammetric camera are so adjusted as to
cause the fiducial center M' to coincide
with the principal point H’.
Principal object axis:
The straight line passing through project-
ion center O and principal point H’.
(Radial distances 7’) :
The distances of the points of penetration
of the rays passing through the image
plane, from the principal point.
Principal object axis:
Coincides with the object-side part of that
principal ray which passes through the
principal point of the image plane.
Radial distances 7’:
The distances of the image points lying
in the image plane, from the principal
point.
(Object angles c) :
The angles between the principal object
axis and the rays.
Object angles 1:
The object-side angles between the prin-
cipal object axis and the principal rays.
(Image function) :
The analytical relation between the object
angles v and the corresponding radial
distances 7’. It is given by the tangent
function:
v =c¢.tan 7.
Camera function:
The analytical relation between the object
angles 7 and the corresponding radial dis-
tances 7” assigned by the optical project-
ion,
In the case of rotation symmetry, this
relation may be represented by the for-
mula:
7 ue. Fr).
In the case of central projection, this
general relation is translated into
1” = e, . tan 7.
Image function:
The relation between the object angles and