'stanbul 2004 
face and Its 
,ecture Notes 
g.. 28 = Sept. 
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X, a MatLab 
ff Geomatics 
Calgary 
>nsor/facilitie 
nted Kalman 
MU's, IEEE 
; CA Pp 273 
)etection and 
ial Sensors. 
Vol. 46. No. 
Time Direct 
fication and 
e on Optical 
1, September 
PERFORMANCE OF MEDIUM FORMAT DIGITAL AERIAL SENSOR SYSTEMS 
M. Cramer 
Institute for Photogrammetry (ifp), University of Stuttgart, Geschwister-Scholl-StraBe 24 D, 70174 Stuttgart / Germany, 
michael.cramer@ifp.uni-stuttgart.de 
Commission III, WG III/1 
KEY WORDS: Digital aerial sensor, medium format, geometric and radiometric performance, GPS/INS, calibration 
ABSTRACT: 
Dealing with digital airborne photogrammetric data acquisition today's main focus is quite often exclusively laid on the large format 
digital sensor systems like ADS40 (Leica Geosystems), DMC (ZI-Imaging) and UltracamD (Vexcel Austria) which are already used 
in practice now. Their advantages are well known, nonetheless, for smaller area projects the use of such large format systems might 
be ineffective. Hence, there still is a need for smaller cameras which can be used in a more flexible and cost effective way. This 
application is addressed within the paper, where the main focus is on the medium format sector, utilizing digital matrix arrays about 
15 Megapixel. After some first remarks on classification of digital matrix cameras the requirements for usage of non-dedicated 
sensors in airborne photogrammetric environments are recalled. The second part of the paper concentrates on the demonstration of 
the potential of two exemplarily chosen medium format cameras, namely the DSS sensor system from Applanix/Emerge, the 
dIGIcam-K14 sensor system from IGI and the Kodak DCS Pro 14n. The DSS is based on a classical analogue medium format 
housing which is supplemented with a digital CCD camera back, whereas the last two are using a standard small format camera 
housing with CMOS matrix array. The performance of such systems is proven from the results of airborne tests. 
I. INTRODUCTION 
Within the last years the development and commercial 
introduction of high resolution digital airborne imaging sensors 
was one major topic in the photogrammetric community. In the 
meantime new sensors like ADS40 (Leica Geosystems), DMC 
(ZI-Imaging) and UltracamD (Vexcel Austria) are available and 
their potential is proven from first experimental tests and pilot 
projects in practice. Such systems will substitute the well 
known analogue large format cameras within the next decades, 
although the analogue image recording using the well-known 
photogrammetric large frame cameras will be in use for a 
several years. Nonetheless, the change to digital sensors is 
inevitable since only a limited number of traditional 
photogrammetric ^ cameras is available from system 
manufacturers and no replacement of stocks will be done. 
Beside the large format digital sensors mentioned above there is 
a need for smaller and more flexible digital sensor systems 
which are designed to address the requirements for a smaller 
format and - in contrary to the very high priced large format 
camera segment - medium or lower priced digital image 
acquisition. In combination with direct georeferencing based on 
integrated GPS/inertial components and with the availability of 
digital elevation models (i.e. from laser scanning (LIDAR)) 
such sensor platforms provide an ideal mapping tool for the fast 
collection of smaller areas and linear features. 
The today's situation in this digital camera field is very viable 
and lots of different systems are already used in practical 
applications. Some of the systems are developed as individual 
items only, others are sold commercially. In order to illustrate 
the situation of smaller format airborne digital camera systems a 
Short overview on the different systems is given in the 
following. The second part of the paper focuses on two 
individual medium format cameras which are presented in more 
detail. First test flight results are given to illustrate the 
performance of such systems. 
In order to classify the different types of airborne digital frame 
sensors the pixel resolution of the resulting digital image is the 
most important criterion. The number of pixels in the digital 
image is not necessarily congruent with the size of the internally 
used digital matrix array, since some of the larger formats are 
realized combining several arrays. Following the classification 
given by Petrie (2003) one can divide three different system 
classes: 
e  Small-format cameras, generating images in the range 
up to 6 Megapixel (i.e. image formats up to 2000 x 
3000 pixel typically by using one equal sized matrix 
array). Sometimes up to four of those arrays are 
combined to obtain full resolution colour imagery. 
*  Medium-format cameras with image formats around 
15 Megapixel (i.e. image formats 4000 x 4000 pixel or 
better. The RGB and CIR images are typically 
realized using Bayer colour mosaic filter to interpolate 
the colour information. 
e … Large-format cameras having a format of at least 36 
Megapixel (i.e. image formats up to 13500 x 8000 
pixel). These image formats are realized by 
combination of several smaller format matrix arrays 
since the largest available single matrix arrays allow 
for the recording of 9.2k x 92k pixels and is used in 
aerial reconnaissance systems (Gorin et al 2002). In 
this context “smaller format” has to be treated relative 
since the matrix areas used for acquisition of sub- 
images are sized about 4k x 2.7k (UltraCamD) or 7k x 
4k (DMC), which is closer to the medium sized 
category in the sense of the nomenclature given here.