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SEMI-AUTOMATIC CAMERA CALIBRATION AND IMAGE ORIENTATION 
USING THE CIPA REFERENCE DATA SET 
Frank A. van den Heuvel 
Delft University of Technology, Department of Geodesy 
Thijsseweg 11, 2629JA Delft, The Netherlands 
E-mail: F. A. vanden He u ve I 7/ eeo .tudelft.nl 
KEY WORDS: Architecture, Line-photogrammetry, Camera Calibration, Image Orientation, Object Reconstruction, Automation 
ABSTRACT 
The goal of this paper is to demonstrate the applicability of line-photogrammetric methods by applying them to a subset of the 
images of the CIPA reference data set. This data set is set up by CIPA (The ICOMOS / ISPRS Committee for Documentation of 
Cultural Heritage) in 1999 and consists of images of a historic building: the old city hall of Zürich. Although object reconstruction is 
regarded as a final goal of a photogrammetric recording, this paper focuses on two tasks in architectural photogrammetry: camera 
calibration and image orientation. The line-photogrammetric methods applied for these tasks have been developed in the past years. 
These methods have in common that they require the extraction of image lines and information on the orientation of the related 
object lines. The methods are not discussed in detail in the paper. 
For camera calibration manually and automatically extracted straight image lines of five images were used. The required parallelism 
and orthogonality information was obtained automatically by vanishing point detection. Correspondence between line features in 
different images is not required. Camera parameters and their precision are estimated in a least-squares adjustment. The results 
correspond well with the camera parameters provided in the CIPA reference data set itself and those provided in the literature. 
The semi-automatic method for image orientation relies on line extraction and vanishing point detection as well. Furthermore, 
coplanarity of object lines that reside in a façade is assumed. Fully automatic relative orientation is not possible for all four image 
pairs used in the experiments. Depending on the image configuration and settings of a few parameters, one or two image points have 
to be measured for successful orientation. These points are chosen on the corners of the building and thus in the overlap of 
consecutive object models. This allows the scale to be transferred from one model to the next. Then this method for image 
orientation results in a partial reconstruction of the building. 
Figure 1: The subset of used images. Images 8, 9, 10 (top row), 11, 6, 3, and 16 (bottom). Images 8, 9, 10, 11, and 6 have been used 
for calibration. The images in the bottom row are used for the image orientation experiments. 
1. INTRODUCTION 
1.1. Line-Photogrammetry 
In the past years line-photogrammetric methods were developed 
for the main tasks in architectural photogrammetry, i.e. camera 
calibration (Heuvel, 1999a), image orientation (Heuvel, 2002), 
and object reconstruction (Heuvel, 1999b). These methods have 
in common that they require the extraction of image lines 
(manually or automatically) in combination with information on 
the orientation of the related object lines. The goal of this paper 
is to briefly introduce these methods and to demonstrate their 
applicability by applying them to images of the CIPA reference 
data set. 
1.2. The images of the CIPA reference data set 
The CIPA reference data set consists of two sets of images taken 
with two different digital cameras. Here, only a subset of the 
images taken with the Olympus Cl400 is used. Due to the 
manual interaction required for the reconstruction of a 
structured object model, one of the goals of this research is to 
use only a minimum number of images in order to make the 
modelling more efficient. Therefore, only four images taken 
from the corners of the building are selected for image