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New perspectives to save cultural heritage
Altan, M. Orhan

Merging and processing of laser scan data and high-resolution
digital images acquired with a hybrid 3D laser sensor
Johannes RIEGL, Nikolaus STUDNICKA, Andreas ULLRICH
Key Words: RIEGL, laser scanning, photogrammetry, 3D laser scanner, calibrated digital camera, RiSCAN PRO
We present a hybrid sensor consisting of a high-performance 3D imaging laser sensor and a high-resolution digital
camera. We demonstrate the performance capabilities of the system by presenting an example and we describe the
software package used for data acquisition, data merging and visualisation, RiSCAN PRO. Addressing the camera model
and the data structure provides an insight into the well-organized, published and well-documented project format used by
1 Introduction
RIEGL Laser Measurement Systems GmbH is well
known for developing, manufacturing, and marketing
state-of-the-art 3D imaging laser sensors based on the
time-of-flight measurement technique with near-
infrared pulses. The sensors are unique with respect to
the outstanding combination of high measurement
accuracy, a very wide field-of-view, a wide
measurement range, high data acquisition speed, and
proven robustness and compactness.
Recently, RIEGL started to offer the 3D imaging laser
sensors with an optional high-resolution digital camera
firmly mounted to the scanner. The camera used is
calibrated and the orientation of the camera is known
with respect to the sensor’s coordinate system. By
taking a number of images, the whole wide field-of-
view of the scanner of up to 90 x 360 deg can be
covered. The combination of high-resolution calibrated
and registered images and high-quality scan data
provides a clearly improved usefulness of the acquired
data by combining the advantages of laser scanning
and photogrammetry.
We describe in the subsequent sections our companion
software package RiSCAN PRO. The data structure
used by RiSCAN PRO to store all data is published in
order to allow software developers to make full use of
the data acquired and processed with RiSCAN PRO,
e.g., in PHIDIAS from PHOCAD (PHOCAD 2003).
We address the calibration tasks necessary to make use
of the digital images in combination of the scan data.
The capabilities of RiSCAN PRO and the RIEGL
LMS-Z360 instrument with the camera option are
demonstrated by an example.
2 Software Package RiSCAN PRO
RiSCAN PRO is the companion software package to
the RIEGL 3D laser imaging sensors of the RIEGL
LMS-Z series. RiSCAN PRO supports also the
instrument with the camera option. It allows the
operator of the 3D imaging sensor to perform a large
number of tasks including sensor configuration, data
acquisition, data visualization, data manipulation, and
data archiving.
RiSCAN PRO is project oriented. A project is stored
within a single directory structure containing all scan
data, registration information, additional descriptors,
and processing outputs. RiSCAN PRO reflects thus a
data acquisition campaign in the field. The structure of
the project is stored in a text based and documented
project file naking use of the XML format enabling
post-processing software packages to make full use of
the RiSCAN PRO data. Within RiSCAN PRO all data
are organized in a tree structure for comfortable access
and clarity. In the subsequent subsection we describe
the key elements of the tree structure and address some
background information useful for understanding data
handling and data interpretation.
RiSCAN PRO makes use of the following different
coordinate systems:
Scanner’s Own Coordinate System (SOCS) is the
coordinate system in which the scanner delivers it’s
raw data. Figure 1 shows the coordinate system of an
LMS-Z210. The data of every RIEGL 3D laser
imaging sensor contains for every laser measurement
geometry information (Cartesian x, y, z coordinates or
polar r, 0,4> coordinates) and additional descriptors (at
least intensity, optionally color information). Thus the
output of a RIEGL 3D laser imaging sensor can be
addressed as an organized point cloud with additional
vertex descriptors in the scanner’s own coordinate