76 PHOTOGRAMMETRIC ENGINEERING & REMOTE SENSING, 1976 
variety of objects and events to be measured 
and the necessity of flexibility in the solution 
ofthe measuring problems as such. By analyt- 
ical instruments we mean devices for measur- 
ing image co-ordinates and, as a rule, the 
recording of these co-ordinates on a data me- 
dium for later input into a computer. Tradi- 
tional photogrammetric monocomparators 
and stereocomparators are widely used. With 
few exceptions most instruments have plate 
holders for 23-x-23 cm photographs. In a 
majority of cases, close-range photogram- 
metry is based on smaller photograph sizes 
and this might possibly indicate a need for 
the construction of mini-stereocomparators. 
For medical x-ray purposes Zeiss Ober- 
kochen has produced the StR comparator, an 
instrument with measuring accuracy, view- 
ing system, and output of results specifically 
optimised to suit the particular given condi- 
tions. A programmable desk calculator is an 
integral part of the system which means real- 
time calculation of desired quantites. 
Similar in principle, but not as accurate as 
the monocomparators, are the digitizing ta- 
bles, which can be used for large-image for- 
mats and not too high-accuracy requirements. 
This type of instrument could possibly be 
used for the measurement of some types of 
x-rays. 
The analytical plotters have been used ad- 
vantageously for close-range applications. 
These instruments give the project planner 
great freedom in the choice of cameras, orien- 
tations, co-ordinate refinement parameters, 
mathematical models, and output in digital or 
graphical form, using any desired projection. 
This has been thoroughly discussed by Jaksic 
13 
Rectifiers have long been in use for non- 
topographical purposes, and recently modern 
orthophoto printers have been used for archi- 
tectural photogarammery. See, for example 
Seeger?? and Dohler*. 
The analytical approach can offer practical 
methods if there are computers available. 
Today we have at our disposal a broad spec- 
trum of computing machines ranging from 
pocket calculators to desk calculators and 
mini computers to large general-purpose 
computer systems. This is not the place to go 
into the details of computer development but 
it must be pointed out that it has been funda- 
mental to the increasing use of close-range 
photogrammetry. Today's computer technol- 
ogy already provides the photogarammetrist 
with a variety of hardware and software and 
the future will certainly provide him with 
even more flexible solutions to his calcula- 
tion tasks. This holds for programming, and 
intrinsic mathematics as well as for the time 
needed, which means real time presentation 
of results. The instrument manufacturers 
have also taken an interest in and provided 
software for non-topographical photogram- 
metry?5, 
METHODS FOR APPLICATIONS 
NORMAL CASE 
Many applications, perhaps a majority, 
within non-topographical photogrammetry 
are rather straight-forward from the point of 
view of methodology. Photographs are taken 
with stereometric cameras or with single 
cameras according to the normal case. The 
evaluation process is thus simplified for 
graphical plotting as well as for analytical re- 
duction. As the interior and relative orienta- 
tion and often several or all absolute orienta- 
tion elements are known, the number of con- 
trol points can be kept to a minimum. Two 
points are minimum for scaling and locating 
the stereomodel and they are preferably 
positioned as far as possible from each other 
within the model. If a comparatively flat 
model is parallel to the picture planes the 
scale correction is made by a base change. If 
the model is perpendicular to the pictures the 
scaling often is done by a 89-change, because 
this is well correlated with a principal point 
displacement, which often is critical for the 
small “base-height” ratios that are common 
in many cases of architectural and civil engi- 
neering applications.!? Use of metric cameras 
and glass plates makes image-coordinate re- 
finement unnecessary for moderate-accuracy 
requirements and the output from the plot- 
ters in graphical and/or numerical (model co- 
ordinates) form is often what is needed for the 
consumer. In case of comparator measure- 
ments, a reduction to model coordinates is 
very simple and can be programmed even for 
desk calculators. 
GRAPHICAL RESULTS 
For graphical presentation of results the 
manufacturers produce systems of camera 
and plotters for such straight-forward close- 
range photogrammetry. Carbonnel? has di- 
vided these systems into three groups accord- 
ing to the size of the objects to be measured 
and has given samples of the marketed sys- 
tems. The projection planes for the graphical 
plotting can be chosen rather freely, espe- 
cially with the use of tilt calculators now of- 
fered by the manufacturers. New types of 
projections called Geometrals and 
Axonometric projections are demonstrated 
by Carbonnell ^ for architecural purposes. 
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