b 
APPLICATIONS OF PHOTOGRAMMETRIC 
TECHNIQUES TO BUILDING CONSTRUCTION 
Youssef I Abdel-Aziz 
University of Petroleum & Minerals 
Dhahran,: Saudi Arabia 
ABSTRACT 
Precast slab buildings have been used quite 
often in so many places in the world. A core 
of the construction is first built and then 
the slab of all floors are fabricated on the 
ground. These slabs are lifted and pinned on 
the core at certain positions called inserts. 
The positions of those inserts at the four 
Sides are very important in the design. The 
distribution of the slab weight on the core 
depends mainly on the inserts positions. Du- 
ring construction of the core, a very accura- 
te instrument is used to insure the inserts 
positions. However, after concrete settlement 
and creep the inserts positions on the core 
change. The three dimensional position of the 
inserts can be determined using close-range 
photogrammetry techniques. Knowing the three 
dimensional co-ordinates of the inserts, the 
designer can judge whether it is safe to pin 
the slab on those inserts or their positions 
have to be adjusted. This paper gives the 
description of the method applied to a thirty- 
floor precast slab building. 
INTRODUCTION 
In construction of precast slab buildings a 
core of the construction is usually built 
first and the ground-fabricated floor slabs 
are pinned on the core at the inserts. The 
positions of these inserts have to be located 
very accurately so that floor loads are trans- 
mitted to the core at the correct design po- 
sitions. The problem of locating the 3-D po- 
sitions of the inserts within an accuracy of 
* 5 MM. is atypical problem in close-range 
photogrammetry, where two overlapped photo- 
graphs are taken by using a metric camera. 
The convention close-range photogrammetry 
technique is not used here for two reasons: 
- The scale of the photograph, which shows 
the entire face of the core (about 90 me- 
ters height) on the image format, is very 
small. Accordingly one cannot reach the 
required accuracy by using such photographs. 
109 
- The instruments which are required for 
photography and for measuring the image 
co-ordinates or for plotting are very 
expensive. 
The technique which is used in this article 
is an extension of the one developed by 
Abdel-Aziz and Karara (1) in constructing the 
three dimensional test area at University of 
Illinois, USA. In this approach the mathema- 
tical photogrammetric models (such as rela- 
tive and absolute orientations) are applied 
to theodolite-images which are formed analy- 
tically from theodolite measurements. The 
theodolite measurements are mainly the hori- 
zontal and the vertical directions of each 
insert taken from two theodolite stations. 
The main advantage of this approach is that 
only a theodolite is required for measure- 
ments and a calculator for data reduction. 
Moreover, the resulting accuracy of the in- 
serts co-ordinates is better than that obtai- 
ned by using real photographs. 
A complete description of the used instru- 
ments, the required measurements and the data 
reduction is given below. 
INSTRUMENTS 
Only three instruments are required to perform 
the measurements and the calculations of the 
inserts positions. These instruments are: 
- A one-second theodolite. 
- A line object of known length. 
- ^A calculator. 
These instruments ara available in most 
construction firms. 
MEASUREMENTS 
The measurements are taken, for each face from 
two theodolite stations which are on a line 
parallel to the given axis at each face. At 
each theodolite station, one has to perform 
these sets of measurements: 
- The vertical and the horizontal directions 
of each insert. 
- “Phe horizontal direction to the other 
theodolite station. 
- The vertical and the horisontal directions 
of the two ends of the known line object. 
It is apparent that the vertical and the 
horizontal directions are the only required 
measurements. This way: linear measurements, 
which has lower accuracy, have been avoided. 
Also the vertical directions are measured 
according to the procedure given in Abdel-Aziz 
and Karara (1) in which the theodolite spirit 
level screw of the vertical circle need not 
be adjusted. As a result the vertical direc- 
tions are measured without adjusting the spi- 
rit level of the vertical circle. Accordingly 
the plane of the horizontal directions, which 
is the plane of the horizontal circle, is the 
zero reference of the vertical directions. 
This approach saves the time required for ad- 
justing the spirit level of the vertical 
circle as well as increasing the accuracy of 
the inserts co-ordinates. The layout of the 
theodolite stations and the core are given in 
figure 1l.