The bridging of a strip progresses in repeated sequences of inner orientation 
and scale constrained relative orientation. It is based on a scale chosen 
close to that of photographs and the recorded model coordinates are expressed 
in a uniform strip coordinate system. rom the operational point of view, 
there are no specific requirements as to the number or location of ground 
control points. They are identified as such, and measured whenever thev 
become available in any model of the strip. Although the bridging procedure 
is not dependent on the inclusion of their ground coordinates in the 
reconstruction of the strip, it is useful not to wait with checking the 
triangulation fit on control points until the whole stri ip is finished. 
Instead, the NRC software offers an intermediate polynomial transformation of 
any part of the strip currently available, whenever it is geometrically 
justified. 
te 
The transformation can be applied after any particular model of the strip is 
completed (ses module STRIP in Figure 4). The request is entered by 
activating switch P4, as shown in the control section of INIT in Appendix 
A-1. The os structure of the procedure is presented in the flowchart of 
Appendix A-4, In a conversational mode, the operator specifies the 
identification numbers of control points already measured in the stri 
Corresponding coordinates needed for the transformation are automat ically 
extracted from the model coordinate bank and from the available ground 
control point file, and they are stored for this and any subsequent use in a 
disk resident auxiliary work file. Because of this arrangement, there is no 
upper limit set for the number of points used in the transformation. 
i£ 
b 
er 
rj o 
Similarity transformation is plied first and coordinate discrepancies o 
control points are displayed on the terminal together with the corr esponding 
RMS errors characterizing the x, y, z fit. In an editing procedure more 
points may be called in or some points can be eliminated from th 
transiormation. Depending on the level of the ground control support and on 
the length of the so far processed strip, the operator can opt for additional 
polynomial transformation of a specified degree, independently for planimetry 
and for elevations, 
The planimetric transformation is handled by conformal polynomials of up to 
the 3° and its formulation is based on the use of complex numbers, The 
polynomial transformation cf elevations is implemented with the use of the 
following coe£ficients 
(1 x y x? Xy x? x?y), 
associated with five or seven parameters in polynomial transformation of 2? 
or 3?, respectively.