PHOTOGRAMMETRIC ENGINEERING 
priate filters to give a narrow-band input to 
the film. 
The stellar calibration of an aerial camera is 
an ultra-precise method of camera calibration 
by utilization more than two thousand photo 
graphic images of more than 400 stars to 
determine all the elements of interior camera 
orientation and all metric lens defects with a 
statistical validity of one or two microns. The 
refinement is expected to result in significant 
reduction of photogrammetric error propaga 
tion and to lead, ultimately, to the qualifica 
tion of aerial cameras as tools of geodesy. 
A computer program in FORTRAN IV for 
Multiple Station Analytical Triangulation 
(MUSAT) computes the positions and at 
titudes of the photographs simultaneously in 
the coordinate system of the ground control 
using the method of least squares. The final 
position of unknown image points are com 
puted by intersection using the final air 
station positions and camera attitudes. The 
programs are designed to accept a 100-photo 
graph block with up to 100 image points per 
photograph. 
Analytic aerotriangulation was pro 
grammed and documented for the entire prob 
lem of systematic error compensation, three- 
photo strip aerotriangulation, strip adjust 
ments, and the simultaneous adjustment of 
blocks of up to 200 photographs in any over 
lapping configuration with any number of 
horizontal and vertical control points. Provi 
sion was made for varying the relative weight 
of photograph images with radial distance, 
the relative weight of photogrammetric and 
geodetic ground positions, and the weight 
which enforces the condition of colinearity on 
control points. All programs have been pub 
lished in Fortran language. 
A Sequential Independent Model Block 
Analytical Triangulation (SIMBAT) Com 
puter Program is an integrated set of com 
puter programs designed for the analytical 
triangulation of a block of photographs using 
sequential independent models. The programs 
are coded in FORTRAN IV for operation on 
the IBM 7090/7094 computer and in Auto 
math 1800 for operation on the Honeywell 
800 computer. 
The equivalence of color and panchromatic 
aerial photographic films with respect to 
geometric fidelity has been established 
through a series of tests conducted on several 
brands of films. The tests included master 
glass grid-plate exposures for the measure 
ment and analysis of the nature of film dis 
tortion, development of a mathematical 
model for film distortion based upon eight 
camera fiducial marks, evaluation of color 
glass diapositives for emulsion creep, studies 
of error progapation in analytic aerotriangu 
lation, airborne tests of photographic resolv 
ing power and airborne tests of metric aero 
triangulation through the use of the Ohio 
Camera Calibration Test Area. 
The Stereo Image Alternator (SIA) was 
designed to be attached to production-type 
stereoplotting instruments to improve the 
stereoscopic viewing of photo imagery. In this 
system, the anaglyphic filters in projection 
and viewing fields are replaced by synchro 
nized shutters rotating at high speed which 
allow rapid alternate projection of the left and 
right diapositive imagery and synchronous 
alternate viewing by the corresponding eye of 
the operator. The system provides better 
model resolution and brighter models. It 
provides the capability of viewing and work 
ing with color photography in projection-type 
instruments. Manufacturers have provided 
facilities for attaching the device to older 
instruments. 
Semianalytical methods of aerotriangula 
tion were designed to use available computers 
and stereoplotters, including the Kelsh, ER- 
55, B-8, PG-2, C-5, and A-7 plotters. Attach 
ments for these instruments have been de 
signed for the readout of model or strip co 
ordinates. 
An Arizona photogrammetric test site is a 
high-density control area which was estab 
lished in 1965 within the existing Army Map 
Service test area near Phoenix, Arizona, for 
testing photogrammetric techniques and in 
strumentation. The test site provides several 
patterns of monumented and targeted (some 
temporary, some permanent) horizontal and 
vertical control points ranging from a 1/4- 
mile grid spacing over a 2- by 3-mile area to a 
4-mile grid spacing for the entire 16-mile- 
square area. 
A fully analytical aerotriangulation sys 
tem—the Geological Survey’s direct geodetic 
constraint method—has been used success 
fully to provide photogrammetric control for 
mapping two 7.5-minute quadrangles. The 
X and Y photograph coordinates were mea 
sured on the 1:24,000-scale glass-plate nega 
tives with a monocomparator. 
A graphic data recording system will accept 
analog voltages as input from an electronic 
stylus, cursor or other tracing device designed 
to be used with a Cartesian plotter. The 
analog input is converted to digital form and 
fed into a logic system which minimizes the 
number of points required to maintain a 
plotting accuracy of +.005 inches. These 
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