1065 
PICTOMETRY'S PROPRIETARY AIRBORNE DIGITAL IMAGING SYSTEM AND ITS 
APPLICATION IN 3D CITY MODELLING 
Yandong Wang, Steve Schultz, Frank Giuffrida 
Pictometry International Corp. 
100 Town Centre Dr. Suite A, Rochester, NY 24623, 
USA-(yandong.wang, steve.schultz, frank.giuffrida)@pictometry.com 
Commission I, ThS-2 
KEY WORDS: Photogrammetry, Digital, Image, Three Dimensional, Building, Modeling. 
ABSTRACT: 
One of the most significant achievements in digital photogrammetry in the last decade is the development of large format digital 
mapping cameras. In addition to large format digital mapping cameras, a number of medium format digital mapping cameras systems 
have also been developed. At Pictometry, a medium format digital imaging system has been developed and been widely used for 
acquisition of both vertical and oblique images around the world. Since oblique images exhibits rich 3D like information of objects 
on ground, they are widely used in not only 3D measurement and visualization, but also creation of 3D city models. In this paper, 
Pictometry's proprietary medium format digital imaging system will be briefly introduced. Some issues in generation of 3D city 
models using Pictometry digital oblique images will also be discussed. 
1. INTRODUCTION 
With the rapid development of CCD and computer technology, 
a number of large and medium format digital mapping cameras 
have been developed in photogrammetric field (Sandau et al, 
2000, Hinz et al, 2001; Leberl et al, 2003; DIMAC 2008; 
Mostafa, 2003). In contrast to analog mapping cameras, digital 
mapping cameras exhibit a number of advantages. One of the 
most important features of digital mapping cameras is that they 
produce digital images directly without need of photographic 
processing and scanning of negatives and diapositives, and thus 
photogrammetric production cycle can be reduced. At the same 
time, image quality is improved since digital images are free 
from dust marks, spots and scratches. Most digital mapping 
cameras produce 12-bit digital images which have much larger 
dynamic range compared to images produced by films. Thus, 
high accuracy of point measurement can be achieved with 
digital images, especially in difficult situations such as in 
shadow areas. At Pictometry, a medium format digital imaging 
system was developed for acquiring both vertical and oblique 
digital images. Up to now, more than 50 Pictometry imaging 
systems have been deployed in the USA and tens of systems are 
being used around the world. 
3D city modeling has been an active research area in digital 
photogrammetry for a decade and a number of methods and 
systems have been developed for creating 3D city models from 
digital images and other auxiliary data automatically or semi- 
automatically. Two major steps involved in generating 3D city 
models are creation of building models and adding textures to 
the building models. Various methods have been developed for 
creating building models from digital images automatically or 
semi-automatically (Haala and Hahn, 1995; Gulch, 1997; 
Henricsson, 1996; Vosselman, 1999), or from LiDAR data 
(Haala and Brenner, 1997; Rottemsteiner and Briese, 2003; 
Schwalbe et al, 2005). Since both digital aerial images and 
LiDAR data supplement to each other, accurate and reliable 
building extraction can be achieved by fusing digital images and 
LiDAR data (Rottemsteiner and Jansa, 2002; Vosselman, 2002; 
Hu et al, 2006). Adding texture to the created building models is 
important since it makes 3D models more realistic. Different 
approaches for creating building textures have been developed 
to create building textures automatically from aerial vertical and 
oblique images (Brenner et al, 2001; Frueh et al, 2004; Zhang et 
al, 2004). In this paper, Pictometry digital imaging system will 
be briefly introduced. Some issues in creation of 3D city models 
using Pictometry digital oblique images will also be discussed. 
2. PICTOMETRY DIGITAL IMAGING SYSTEM 
2.1. Components of Pictometry Digital Imaging System 
Pictometry digital imaging system has some unique features, 
compared with other digital mapping cameras/systems. The 
imaging system consists of five digital cameras, an integrated 
Global Positioning System (GPS) and Inertial Measurement 
Unit (IMU) and a flight management system. Each camera has 
an array of CCD with about 4.9k x 3.2k pixels. The five digital 
cameras are arranged in such a way that four of them look 
forward, backward, left and right directions at a certain view 
angle respectively and one looks straight down. The camera in 
the vertical direction captures high-resolution vertical images 
and the other four acquire oblique images at different view 
directions at the same time. The onboard GPS and IMU provide 
an accurate position and attitude of each sensor at exposure time, 
thus the images produced by Pictometry imaging system are 
directly geo-referenced images. Like traditional aerial images, 
vertical images provide a vertical view of the terrain surface, 
while oblique images show the side looking of objects on the 
ground such as buildings. Vertical images can be used for 
creation of accurate large scale orthophotos (Wang et al, 2008) 
and oblique images can be utilized for visualization, 
measurement and 3D modeling. Pictometry oblique images 
have been widely used in various applications such as public 
safety, tax assessment, urban planning, 3D city modeling, etc. 
The flight management system is flight planning software which 
determines flight lines, control image overlaps, etc. before and