Part B
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DIGITAL PHOTOGRAMMETRIC TECHNIQUES FOR
ARCHITECTURAL DESIGN
André Streilein, Horst Beyer, Thomas Kersten
Institute of Geodesy and Photogrammetry
Swiss Federal Institute of Technology
ETH-Hônggerberg, CH-8093 Zurich, Switzerland
phone: +41-1-3773047, telefax: +41-1-3720438
e-mail: andre@p.igp.ethz.ch
ABSTRACT
Rapid advances in digital imaging sensors and the availability of powerful workstations make a fully digital
system for architectural photogrammetry feasible. Such a system must be able to derive geometric and seman-
tic information from the architectural object in such a way, that it can be directly used for CAAD (Computer
Aided Architectural Design). Therefore it must provide a sensor-resolution comparable to traditional film-
based systems. À system for Digital Photogrammetry and Architectural Design (DIPAD) is under develop-
ment at the Institute of Geodesy and Photogrammetry in cooperation with the chair of Architecture and
CAAD, both at the Swiss Federal Institute of Technology in Zurich.
À practical project is used to demonstrate the methods and performance of DIPAD. The processing steps from
image acquisition to the three-dimensional geometric and semantic description of the architectural object in a
CAAD-model are presented. Emphasis is placed on novel techniques for the semi-automatic measurement of
architectural features. À comparison of the results for images taken by a camera using a solid-state sensor and
a film-based camera is carried out.
KEY WORDS: Architectural, CAD/CAM, Close-range, Digital system, Feature Extraction.
1. INTRODUCTION
Improvements and new developments in the fields of sen-
sor technology and computer technology allow the acqui-
sition of digital images in video-realtime, without
developing and digitizing a photographic film. À system
for Digital Photogrammetry and Architectural Design
(DIPAD) consists of a Digital Photogrammetric Station
(DIPS) and a system for Computer Aided Architectural
Design (CAAD). The aim of DIPAD is to make the pho-
togrammetric data acquisition and processing easier and
faster, to create a three-dimensional geometric and se-
mantic object description, and to allow visualization and
architectural processing. Therefore the system must be
capable to acquire imagery with sufficient resolution,
process the data with a high level of automation, and pass
the results to a data structure useful for CAAD. This can
be achieved using solid-state sensors and semi-automatic
or automatic measurement techniques. The current status
of DIPAD being developed in a joint project of the Insti-
tute of Geodesy and Photogrammetry in cooperation with
the Chair of Architecture and CAAD at the Swiss Federal
Institute of Technology in Zurich is outlined.
2. PROCESSING STEPS IN DIGITAL
ARCHITECTURAL PHOTOGRAMMETRY
Image data for digital architectural photogrammetry can
be acquired with film-based cameras as well as with cam-
eras using solid-state sensors. Conventional film-based
cameras still provide for an unsurpassed photographic
resolution. For example, images with over 6000 by 6000
pixel would be required to match the resolution of a me-
825
dium format film camera. But the difference between
film-based cameras and cameras using solid-state sensors
concerning the photographic resolution shrinks more and
more. On the other hand the disadvantage of film-based
cameras is that the film must be developed and digitized
before the data is available for processing in a digital sys-
tem. Whereas the image data of solid-state cameras is im-
mediately accessible. This offers, among others, the
advantage of quality control for image acquisition on the
spot.
Figure 1 depicts the processing steps in digital architec-
tural photogrammetry. After image acquisition, orienta-
tion and calibration, the geometric relations among all
images and between images and object are known. The
semi-automatic and automatic measurement techniques
are used for the measurement of image coordinates.
Herein, the identification of architectural features and the
semantic classification is performed. The three-dimen-
sional object coordinates are determined within a bundle
adjustment. The result of the photogrammetric process-
ing is a three-dimensional geometric and semantic object
description, which can be passed automatically to the
CAAD-system for further architectural processing.
The photogrammetric processing with the Digital Photo-
grammetric Station (DIPS II, Grün and Beyer, 1990) is
meaningful because of the capability using semi-auto-
matic and automatic measurement techniques. Some of
these measurement techniques are described in chapter 5.
DIPS consists primarily of a network of workstations
from SUN-Microsystems, to which special purpose sys-
tems like an image acquisition workstation, an analytical
plotter, personal computers with interfaces for special
