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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
