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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