CIP A 2003 XIX th International Symposium, 30 September - 04 October, 2003, Antalya, Turkey 
translation vector is the scanners position and the 
column vectors (r^ r 2 j r3j) T are the directions of the local 
coordinate axes in PRCS. 
Figure 2: Example for the PRCS, GLCS, and a number of SOCS at 
a site for scanning a building. 
Each scan position holds the scan data taken at this 
scan position, stored in the scanner’s binary data 
format with extension 3dd. Furthermore, each scan 
position holds it’s SOP information. In order to 
transform data from SOCS into PRCS the data points 
are simply multiplied with the SOP matrix (M S op) of 
the scan position. 
In case a data point P have to be transformed from a 
specific scan position into GLCS, a sequential 
multiplication has to be carried out, first with the Msop 
matrix of the scan position to get into PRCS, then Mp 0 p 
which transforms from PRCS into the GLCS. 
The process of registration of the various scan 
positions in the PRCS is basically the determination of 
the respective M S op- This process is based usually on 
tie points within RiSCAN PRO. Tie points are 
managed by tie point lists (TPL). Tie points are 
usually defined by retro-reflective targets showing up 
clearly in the intensity data of the scan data and which 
can also be accurately localized by the use of total 
stations. The tie point itself is commonly the center of a 
reflective target. 
Every project can hold one tie point list in the project 
coordinate system TPL (PRCS). Usually the data are 
gained by measuring the position of the tie points with 
a total station or by other means, e.g., DGPS. If the tie 
point coordinates are available in global coordinates, 
they are entered into the global tie point list, TPL 
(GLCS), and are subsequently transferred into the TPL 
(PRCS) by defining an appropriate matrix M> 0 p to 
fulfil the requirement of single precision 
representation. 
In order to register a single scan position into the 
project coordinate system, a tie point list in the SOCS 
system have to be acquired, which s done by fine- 
scanning the retro-reflective targets visible from the 
specific scan position. RiSCAN PRO extracts retro- 
reflective targets from a so-called overview scan or 
panorama scan and supports the automatic subsequent 
sequential fine scan of the targets. Once sufficient tie 
points have been gained M S op can be determined 
automatically and the scan data is transferred into the 
project coordinate system as well as into the global 
coordinate system. 
3 Use of high-resolution images 
within RiSCAN PRO 
RIEGL 3D imaging sensors can be equipped with an 
optional high-resolution digital camera. The images 
can be used to assign a color to the vertices of the point 
cloud data or to apply the images as a texture to the 
meshed surface generated from scan data. Before being 
able to apply the image information to the scan data a 
camera model has to be selected and the camera has to 
be calibrated. 
RiSCAN PRO makes use of an 10-parameter model for 
the internal camera calibration (Intel 2003). The 
internal parameters of the camera model can be 
determined within RiSCAN PRO in different ways and 
are described below in the calibration tasks section. In 
order to make use of the image data calibration data 
holding the internal parameters of the camera have to 
be available. The calibration data are contained in the 
calibrations section of the project file. The calibration 
data have to be determined for every camera to be used 
and for every setting of the camera’s focus and aperture 
to be used. 
In order to utilize the image information also the 
external orientation of the camera has to be known. The 
definition of the external orientation differs for the two 
different kinds of images managed in RiSCAN PRO: 
Type 1 Images: Images taken when the camera is 
mounted on top of the scanner 
Type 2 Images: all other images, i.e., when the camera 
is NOT mounted on the scanner 
Type 1 images are stored in the folder corresponding to 
the scan position at which the images have been taken. 
As the camera is firmly mounted on top of the scanner 
and the orientation of the rotational platform is well 
known, the orientation of the camera within the 
scanner's coordinate system is well defined after