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A COMPARISON BETWEEN TWO COMPARABLE 
ANALYTICAL METHODS OF DATA REDUCTION 
FROM NON-METRIC PHOTOGRAPHY 
Dr.Adel Ahmed Esmat Mahmoud 
Lecturer, Department of Civil Engineering 
AL.Azhar University, Cairo, Egypt. 
Commission V. 
Abstract 
This paper discusses, contrasts and studies theoretically and experimentally 
the accuracies obtained from two comparable analytical methods of data 
reduction from non-metric photogrophy . 
Both methods depend mainly on the perspective theorem. 
These methods are(1)the Artificial photo perspective Transformation (APPT) 
developed by Thompson (1962), and(2) the metric photo perspective 
Transformation (MPPT) developed by Gruen (1985). 
We can say that the comparison is between : 
(1) The surveying technique wherein an imaginary camera (theodolite) is 
used for measurements; and 
(2) The photogrammetric technique wherein a real camera is used for 
measurements., Three different cameras (Zeiss Jena)UMK,Wild P32 and 
Galileo Santoni metric cameras were used in the comparison between the 
above two methods. A non-metric camera was also used (Nikon FM 35 mm),as 
well as a Wild T2 one second theodolite. A set of analysis of results , 
concluding remarks and recommendations was achieved. 
1. INTRODUCTION 
In the APPT method we transform the image co 
- ordinates from the non-metric photograph to 
image co - ordinates on imaginary metric 
photographs by using perspective 
transformations In the MPPT method we 
transform the image co - ordinates from the non 
-metric photograph to image co - ordinates on 
real metric photographs by using the same 
transformations. 
In our comparison between the two methods , 
either theoretically or experimentally ,we shall 
assume that: (1)the non - metric camera used 
with both of the methods was the same ; 
(2) the object dimensions ( W,H ) observed by. 
both the methods were the same ; 
(3)the base distance ( B ) and the object 
distance (D) for both the imaginary camera or 
theodolite and the metric camera were equal 
and 
(4)the condition for photography should be 
standarised as far as possible 
2. THEORETICAL COMPARISON 
The comparison between the APPT and MPPT 
methods 
will be now concentrated in the following main 
factors : 
(1)the accuracy of the image co-ordinates of the 
metric and fictitious photographs ; 
(2)the accuracy of the operator in orienting the 
metric camera and the theodolite in the field 
(w,g,k) and measuring their co-ordinates 
(Xs, Ys,Dg) and 
(3)the pointing accuracy of the operator . 
2.1The Accur f the Im -ordin f 
he Real icit Pi 
The accuracy of the image co-ordinates 
achieved from the surveying technique 
(artificial photographs ) is generally better than 
that achieved from the photogrammetric 
technique ( metric photographs ) . 
The accuracy of the fictitious photographs is a 
function of the accuracy of measuring and 
computing the control points and the horizontal 
and vertical distances between the two stations 
( Byand By), e.g if the chosen focal length (f) of 
the imaginary camera is 100 mm , the mean 
object distance (D) is 100 m and the accuracy of 
computing and measuring the control 
points ,B, and By is 0.5 mm , in this case we 
can achieve an accuracy in the co-ordinates of 
the fictitious photographs of 0.5 um . This level 
of accuracy cannot be achieved by using metric 
photographs.