440 
coordinates and Cartographers have chosen to present flat 
maps of the earth. witha host of mapping transforms. 
Control 
— 
  
Plotted 
——ÓÀ 
Data 
Figure 4 
The rectangular coordinate system shown on the right in figure 
4 is the one chosen by the photosrammetrist which best:suits 
the pair of photographs being employed and also minimizes 
computation of the central perspective transformation to each 
photograph. This system is usually unique for each photopair 
and as such does not qualify .for standardization» Likewise, 
the output coordinate system for plotted data is usually 
chosen in particular for the "best fit" to che areas being 
mapped and as such can take on a variety of shapes. The most 
universal of the three ‚(upper left in fig. 4) is that of the 
geodesist--the curvilinear system in latitude, longitude and 
height. These systems are usually consistent over large con- 
tinental land masses and are precisely defined by two para- 
meters--either two axes of an ellipsoid (a and' b) or^ by one 
axis (a) and an eccentricity (e-squared). Sometimes the figure 
is given by the axis (a) and a flattening {f); however there 
are expressions that relate the four parameters. Most import- 
ant is the fact that there are rigorous transformation to and 
from Cartesian coordinates. That is, for transform fron 
geodetic coordinates (5,4, and h) to:/Cartesian. coordinates 
(X. Y, and 2), one. uses. (assuming positive longitude: west): 
Ms gu fret stus 
X = (N+h) 005$ cosA ; 
[1] 
Y ==(N+h)cosé sinA 
us [" (iet) v^] sind 
Conversely, to transform from Cartesian to geodetic coordinates: 
Af = f Y) "2 
À = Cos, Xs) MER /27 
ó = fan f Z(a«») /a ( 54^]