Boersma, Saskia M. 
  
PHOTOGRAMMETRIC WOUND MEASUREMENT 
WITH A THREE-CAMERA VISION SYSTEM 
Saskia M. Boersma*, Frank A. van den Heuvel*, Adam F. Cohen**, Rick E.M. Scholtens*** 
*Department of Geodetic Engineering 
Delft University of Technology, Delft, The Netherlands 
**Centre for Human Drug Research, Leiden, The Netherlands, 
***Het Groene Hart Ziekenhuis, Gouda, The Netherlands 
Saskia_Boersma@hotmail.com, F.A. vandenHeuvel(g)geo.tudelft.nl, ac(g)chdr.nl 
Working Group V/4 
KEY WORDS: Accuracy, calibration, Digital Surface Model, medical, wound measurement, trinocular vision system 
ABSTRACT 
A three-camera vision system is developed for the measurement of the shape and volume of wounds, especially 
pressure sores. This system is able to assist physicians in monitoring the healing process of these wounds. The vision 
System consists of three progressive scan video cameras that are mounted on a triangular frame with a light source with 
optional texture projection in the centre. The cameras are not designed for high accuracy measurement purposes. This 
makes the calibration of the system decisive for the accuracy of the Digital Surface Model (DSM). Eight image triplets 
of a testfield are acquired for system calibrati 
designed for aerial photogrammetry, automatically generates a DSM. A DSM is computed for each of the three image 
pairs. Differences between the three models are calculated to get insight in the obtained precision of the DSM. To 
increase the quality of the DSM, the three models are combined to form one final DSM. The resulting DSM is used to 
calculate the wound features of interest. The applicability of the technique in practice is tested on artificial and real 
tween different models showed that a precision of better than 0.7 
projection. Future work has to concentrate on the integration of the 
components in one user-friendly real-time measurement system for wounds, and on further improvement of the 
accuracy of the system. 
1 INTRODUCTION 
1.1 Motivation 
A recent nation-wide prevalence survey 
in The Netherlands revealed the prevalence of pressure sores to be 14 percent 
among patients in university hospitals, 2 
0 percent in general hospitals, 29 percent in residents of nursing homes and 12 
: annual direct costs of pressure sores in The Netherlands are estimated to be at 
least 0.5 billion Euro (Health council of The Netherlands, 1999). The medical profession is seeking methods address 
this problem. In order to investigate methods for curing pressure sores a physician has to be able to judge the healing 
process. The interpretation of the results is subjective, because there is a great variation in the measurements of wound 
healing. Consequently, it is difficult to analyse research results. Therefore, there is a need for an objective and practical 
method to determine the shape of these wounds and derived quantities, such as the contour and the volume. 
1.2 Pressure sores 
  
  
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