DIGITAL PHOTOGRAMMETRY AND LASER RANGE CAMERA 
FOR PHYSIC MODEL GEOMETRY DETERMINATION 
M.Barbarella 
A. Vettore 
Dip. DISTART - Università di Bologna - Italy 
Dip. Territorio TESAF - Università di Padova - Italy 
Viale Risorgimento 2-40100 Bologna 
AGRIPOLIS - Statale Romea 16 
Phone +39-051-6443106 fax +39-051-6448073 
35020 Legnaro (Padova) 
e-mail: mauriziobarbarella@mail.ing.unibo.it 
Phone +39-049-8275580 fax +39-049-8272713 
e-mail: vettoan@uxl.unipd.it 
Commission VI, Working Group 3 
ABSTRACT 
In this work we present a comparison between two different techniques to generate a DEM of a sample mould. In the 
first part an automatic extraction of object’s DEM from orthophotos is performed using the digital photogrammetric 
software OrthoEngine by PCI, while in the second part the mould is scanned by a laser range camera (BIRIS), by which 
the range data are directly acquired in a computer readable form. 
Then, the resulting DEMs are compared through Surfer software in order to evaluate the accuracy achievable from these 
techniques in 3D object model reconstruction. 
1. INTRODUCTION 
Since a few years laser scanner sensors are widely 
employed in applications regarding 3D object model 
reconstruction. The major advantages of using these 
sensors are as follows: 
• Limited divergence of laser beam yields a narrow 
spot onto the target, allowing to acquire a relative 
dense set of 3D points. In this way it is possible to 
perform very detailed surveys. 
• The highly directive beam allows to scan irregular 
object, giving more detailed information about its 
surface and form. 
• Range data are directly acquired in digital format, 
therefore, unlike digital photogrammetry, no data 
conversion is required. In this way the data can be 
immediatly managed by processing software. 
Today the reliability of laser scanner sensors is curren 
tly tested both in close-range photogrammetry applica 
tions and in outdoor environment, i.e. DTM generation 
from airborne laser scanner (ALS). 
As mentioned before, one of the major advantages of a 
laser scanner system is the great amount of achievable 
data, that allows us to build a 3D object model with 
high detail capability. 
The aim of this work was therefore to investigate the 
accuracy in 3D object reconstruction by a laser scanner 
camera, in comparison with the 3D model resulting 
from application of digital photogrammetric triangula 
tion to orthophotos of same object. To this end the cor 
responding object DEMs were extracted from data col 
lected with the two different measurements systems, 
and compared through a surface mapping software. 
2. THE DIGITAL PHOTOGRAMMETRIC DEM 
In order to extract a DEM from orthophotos of a 
sample mould (see Fig. 1 and 2) a digital non-metric 
camera was employed for image acquisition, then the 
(X, Y, Z) coordinates of mould points were computed 
by a stereo photogrammetric workstation, yielding an 
output ASCII file for succeeding DEM generation. 
The set of images was acquired from target through 
Kodak Professional DCS 410 digital camera. Since this 
is a non-metric photocamera it was calibrated, before 
data collection, with a calibration algorithm developed 
at University of Padua. 
The specifications of adopted camera are as follows: 
• CCD-field: 1524 x 1012 pixels; 
• Image size: 14 (H) x 9.3 (V) mm; 
• Square pixels size of 9 pm ; 
• PCMCIA card with 170 MB of storage, up to 26 
images can be read offline into computer. 
As regards the interior parameters, the camera calibra 
tion yelded following results: 
• Focal length : - 83.328 mm; 
• Principal point: 0.13925 (H), 0.21974 (V) mm; 
• Radial distortion coefficients: 
Kj= -1.25999E-005 K 2 = 6.67158E-009 
The images were then rectified and the depth of the 
mould points were determined using the digital photo 
grammetric software OrthoEngine by PCI, courtesy 
provided from Geotop Inc. (Ancona-Italy). As final