CLOSE RANGE PHOTOGRAMMETRIC APPLICATIONS USING ASTRI
E. Stambouloglou
Greece
COMMISSION V
ABSTRACT
This paper presents test and results for
ASTRI (Analytical STereo Restitution Instrument), the
for Analytical Photogrammetry.
1. INTRODUCTION
Architectural Photogrammetry
should be of high
(Greece) because of
of Hellenic
centrated in
applications
interest in Hellas
the enormous amount
cultural heritage con-
the country and the Mediter-
ranean area during the last three thou-
sand years.
Unfortunately this interest is not acti-
vated very often. It is always a custom
in Greece to get
Photogrammetric
advantage of the
approach in cases where
conventional methods have no chance to
provide the appropriate surveys to the
specialists for the conservation and re-
storation of Monuments and Sites.
Early last year the Municipality of the
City of Rhodos entrusted the
Photogrammetric Survey of the Medieval
Walls to my private firm " Stambouloglou
and Associates'.
The Walls surround the old city with a
perimeter of approximately five kilome-
tres. A deep ditch with 20 to 50 meters
width separates the walls and the old
city from the modern one.
According to the signed contract two
types of Photogrammetric surveys where
required. The first was the facades of
the Walls in scale 1:200 for the total
perimeter and the second was the detail
survey of facades in scale 1:50 for some
selected areas damaged or in danger of
demolition. The requirements of the first
type of survey where limited to the de-
scription of basic lines, gates, windows,
the wall border, and the perimeter of
damaged areas. For the second type of
survey a detail restitution of the
facades was required with all the above
"lines plus the details of the stonework
(practically survey of every stone).
The Medieval Walls are
can be described geometrically with
planes and a few curved surfaces. Two
approaches where selected for the first
type of Photogrammetric surveys in scale
1:200. Rectification for the planes and
Stereo restitution for the curved sur-
a complex which
close range applications using the
low cost simple system
faces. Two cameras where
photos. An UMK-10/1318 JENA
35 mm amateur camera equipped with three
lenses 28, 50 and 150 mm. A total of ap-
proximately 1000 photos where taken. The
first camera was used for the survey in
1:50, combined with the analytical plot-
ter DIGICART-40, while the second for
the scale 1:200 with ASTRI. A total
amount of 6100 control points where
observed and determined using conven-
tional geodetic methods and equipment,
the digital theodolite T-1000 WILD
equipped with a DIOR 3002 WILD EDM.
used for the
and a CANON
The control points were all
detail points on the Walls
natural
surfaces dete-
rmined from ground stations. An Ana-
lytical rectification program using the
digitizer and the DLT method gave the
solution to the survey of the planes. As
an extension to this first approach the
new low cost system ASTRI was conceived
and constructed for the reduction of data
from non-metric, semi-metric and metric
cameras for both monoscopic and stereo-
scopic photos. A description of the ASTRI
is given in Stambouloglou 1992.
2. EVALUATION OF THE EXPECTED ACCURACY
The expected accuracy of the Analytical
Photogrammetric Restitution is evaluated
theoretically with complex or simple for-
mulae depending on the mathematical
model and the assumptions used. Complex
formulae give the rigorous evaluation of
the accuracy concerning all measured data
(direct or indirect measurements). Most
of the Stereo Photogrammetric applica-
tions are very close to the normal case,
for which the evaluation of accuracy can
be derived with the application of error
propagation to the simple formulae
Bx omini
where
