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Dept. of
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INITIAL RESULTS OF THE ITALIAN PROJECT ON DIRECT GEOREFERENCING IN
AERIAL PHOTOGRAMMETRY
RIA CY ^ :2ni0) anid LE : c Es + : : à
V. Casella? , M. Franzini", G. Forlani^', R. Galetto?, A. Manzino*, F. Radicioni'!, G. Sona', B. Villa?
(a) M B a: ! de bi
"DIET - University of Pavia - Italy - (vittorio.casella, marica.franzini, riccardo.galetto) @unipv.it
D . . . ~ . . . bud
DICATA — University of Parma - Italy - gianfranco.forlani@unipr.it
(? DIGET — Technical University of Torino - Italy - ambrogio.manzino@polito.it
© DICA — University of Perugia - Italy - topos@unipg.it
“ DIIAR — Technical University of Milano - Italy - giovanna.sona@polimi.it
(? DIRAP — University of Palermo - Italy - bevilla@unipa.it
KEY WORDS: Photogrammetry, GPS/INS, analysis, calibration, triangulation, adjustment, accuracy, reliability.
ABSTRACT:
The paper describes one of the first outcomes of an Italian national research Project on inertial positioning in photogrammetry. The
focus of the paper is on the quality which is attainable from direct photogrammetry in an industrial production context.
Even if GPS/IMU-aided photogrammetry is used rather widely, it is still useful to perform rigorous quality assessment of this
method, because large and diverse case studies are necessary to prove and quantify the capability of a new methodology. Besides, it
is necessary to evaluate such methodology in the ordinary operational conditions, rather than considering data acquired in a dedi-
cated, special context.
To fulfil these requirements several different flights were considered, which were acquired by an Italian photogrammetric company
before the beginning of the Project, purely for production aims, and rigorous quantification of residual parallaxes and accuracy was
performed. The origin of the considered data, which is not research-oriented, and the vast and heterogeneous case study — different
cities, different flights, different calibrations- make the described test very significant and reliable.
1. INTRODUCTION
An Italian national research Project on direct georeferencing in
photogrammetry is in progress. Its title is /ntegrated Inertial
Positioning Systems in Aerial Photogrammetry and it is chaired
by prof. Riccardo Galetto of the University of Pavia. The
Project was joined by nine units belonging to as many Italian
universities. The Project is greatly articulated and one of its
aims is quality assessment of images which have been acquired
and directly oriented within an industrial production frame.
Quality assessment of direct georeferencing in photogrammetry
is of great interest because this technology is developing rapidly
and the case studies already acquired are significant but not
exhaustive. Besides, many of the most significant tests, such as
the OEEPE test and those performed by the University of
Stuttgart, were conducted with dedicated data, which was
acquired exclusively for research purposes. Such studies are
necessary because they allow estimation of the quality which is
attainable using a certain technology in the best possible way;
nevertheless it is important to ascertain what the attainable
quality in an ordinary daily work-flow is and how high it's
reliability. ;
This is the precise aim of the described step of our Project,
which has two main goals: a systematic evaluation of residual
parallaxes, which are sometimes critical in directly oriented
Images, and a systematic assessment of accuracy. The origin of
the considered data, which is not research-oriented, and the vast
and heterogeneous case study -different cities, different flights,
different calibrations- make the described test very significant
and reliable.
To perform this phase the nine working groups, belonging to
different cities, were given a block above each city, together
881
with EO data measured by an inertial integrated sensor. The
data was supplied by the Italian company Conipagnia Generale
Ripreseaeree - CGR, whose headquarters are in Parma, which
joined the Project. The images were acquired before the begin-
ning of our Project, within an industrial project called “Ter-
raltaly-City", devoted to the production of high detail orthopho-
tos for more than 110 Italian cities.
The paper describes the data used for testing, the methodology
followed and the main results of the analysis.
2. THE DATASET
Each unit was given a rectangular block constituted of 3 strips
and 8 images per strip. The blocks were acquired by a plane of
the CGR company equipped with a Leica RC30 camera,
provided with an Applanix POS/AV 510 sensor. The focal
length of the lens was 300 mm; the average relative height of
the flight was 2900 m; the average image scale, 1:9300. The
digital images we used were acquired by a Zeiss SCAI scanner
with a resolution of 14 microns per pixel.
Two external orientation sets have been delivered: the ones
acquired through a direct sensor orientation process (4PP) and
the ones obtained with a light integrated sensor orientation
(AAT), calculating an airborne triangulation whose observations
only consist in the photogram external orientations of the APP
type and the image coordinates of tie points, automatically
measured. The sensor's calibration was performed by the CGR
company with the standard Applanix software.
3. MEASUREMENTS PERFORMED BY THE UNITS
The research units performed several measurements on the
images and on the ground:
