CI PA 2003 XIX th International Symposium, 30 September - 04 October, 2003, Antalya, Turkey
castles where people visiting the site should not
be disturbed. Due to the large field of view of
the scanner, 360° horizontally (azimuth) and
270° vertically (elevation), the scene to be
modelled has to be surveyed only from a few
points of view. Together with the high
performance measuring device (up to 625,000
points per second), this enables the user to
survey the scene in a very short time. A typical
scan with 4,200 rows and 10,000 points per row
is completed in less than 180s. As it is often not
necessary to take a scan of the whole environ
ment, it is also possible to define a special
window which is intended to be surveyed.
Important objects can be measured down to the
smallest details with this feature, as you can
easily set a very high resolution for this win
dow. The maximum resolution of the sensor is
up to 20,000 rows with up to 36,000 points
which results in an excellent area coverage and
resolution of small structures.
Figure 1: IMAGER 5003
The laser scanner can operate in total darkness
as well as in daylight. This facilitates measure
ment, since no additional illumination is need
ed. This fact can be of particular importance for
cultural sites where certain areas, castles or
churches, are difficult to illuminate.
The great advantage of the laser scanner is that
the data is stored directly on a computer during
the measurements and therefore is digitally
available. The laser scanner is controlled with a
standard PC or laptop. The control program (see
chapter 2) is user-friendly and easy to under
stand, so that even untrained people can take
scans without problems. The point cloud, which
is the result of a measurement, has to be trans
formed into a CAD model for documentation
purposes. This transformation is a semi
automatic process, done by special algorithms
of programs which are developed especially for
processing the point clouds.
1.2 DLR Panoramic colour camera
This camera is developed in a common project
between an industrial company and the
Deutsches Zentrum fur Luft- und Raumfahrt
(DLR) for environmental documentation purpo
ses. The camera consists of a rotating unit
which rotates an integrated line chip 360° to
achieve a full view of the environment. By
using three line chips with each 10,000 ele
ments a high resolution can be achieved with
the imaging. Three lines (RGB) provide each 16
Bit information of the environment and guaran
tee a high dynamic range with monitoring.
The resulting images consists of a maximum of
yl,
Figure 2: Panoramic camera
10,200 by 500,000 pixels each containing three
Mbit RGB values. The image is stored by a
specially developed frame grabber onto the hard
disk of a computer. A typical scan (10,000 x
30,000) usig a special optical lens system by
35mm optical focus length by the DLR camera
takes about 3min (normal light) up to 20min
(artificial illumination), mainly depending on
the ambient illumination conditions and the
number of rows to be measured with the
camera.