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EVALUATION OF A LOW COST DIGITAL PHOTOGRAMMETRIC SYSTEM 
FOR MEDICAL APPLICATIONS 
P.R. Thomas and I. Newton 
Department of Surveying, University of Newcastle upon Tyne, Newcastle upon Tyne, NE1 7RU, UK 
K.B. Fanibunda 
Department of Oral Surgery, School of Dentistry, University of Newcastle upon Tyne, Newcastle upon Tyne, NE2 4BW, UK 
Commission V, Working Group 5 
KEY WORDS: Digital, Application, Medicine, DEM/DTM, Low Cost System, Performance. 
ABSTRACT: 
The availability of low cost, off-the-shelf digital imaging equipment and PC-based software has the potential to bring digital 
imagery and digital photogrammetry to a wider range of users. This paper investigates the possible use of such systems in the 
medical field, a field in which photogrammetry has been widely investigated as a measurement tool but with limited success to date 
so far as routine usage is concerned. These digital systems may offer not only a low cost solution but also a degree of automation, 
both of which are seen as essential if the use of photogrammetry is to increase in this application area. 
1. INTRODUCTION 
Photography is already widely used in medicine for recording 
purposes but there now exists the possibility of changing to 
digital imagery. Digital cameras are easily obtainable at a 
reasonable cost and still video cameras, such as the Kodak 
DCS series, are as convenient as normal film cameras in terms 
of portability and handling. Digital imagery may also be 
obtained through high resolution scanning of conventional 
photography, with Kodak PhotoCD being a particularly 
attractive system for small format photographs. This system, 
discussed in Thomas et al (1995), is available through many 
electronics and photographic outlets, and provides photographic 
quality digital imagery on compact disc at a low cost. Handling 
of digital imagery requires a PC workstation with software to 
read the image format and to manipulate it, whilst the operator 
needs some computer skills. 
Having obtained digital imagery, digital data processing is able 
to produce photogrammetric measurements at a reasonable cost 
and with some degree of automation. Several low cost 
packages are now available incorporating image processing 
operations, automated image correlation and stereoplotting 
capabilities. Moreover these software packages may be 
operated by those with a limited knowledge of 
photogrammetry. 
This paper discusses the use of a low cost, off-the-shelf digital 
photogrammetric system in the medical field. Two particular 
applications are featured to illustrate the possibilities: one 
relates to the planning of oral surgery, the other to automated 
back shape measurement. In both cases, methodologies are 
outlined and initial results are given. 
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2. EQUIPMENT USED 
2.1 Digital data capture 
Digital data capture for this work was either by a Kodak 
DCS200 still video camera or by a Hewlett Packard (HP) 
desktop scanner. 
2.1.1 Kodak DCS200 still video camera: This camera is 
based on a conventional 35 mm camera body (the Nikon 
N8008s) and provides high quality, digital colour output direct 
to a PC. The imaging area of the CCD chip is 14 mm x 
9.3 mm, which is the same aspect ratio as 35 mm film but the 
dimensions are smaller by a factor of 2.6. The same coverage 
as for a 35 mm camera can therefore be obtained using a lens 
with a focal length that is shorter by a factor of 2.6 (e.g. a 
20 mm lens instead of a 52 mm lens). The chip contains 1524 
x 1012 pixels which gives a pixel size of 9 micrometres. The 
camera is used in a similar way to any 35 mm camera and the 
images are downloaded to a 80 Mb internal hard disk. 50 
exposures can be made before the disk is full and must be 
downloaded. The current cost of a Kodak DCS200 camera is 
around $10000. This camera is just one of a range of Kodak 
DCS cameras and further details may be found in Graham 
(1995). 
2.1.2 HP ScanJet Plus desktop scanner: This is an A4 size 
flatbed scanner. It is able to produce a 4-bit or 8-bit grey scale 
digital image from a conventional photograph and has an 
optical resolution of 300 dots per inch (dpi) giving a pixel size 
of around 25 micrometres. An A4 size image can be scanned in 
around 10 seconds. The current cost of an equivalent scanner 
is $500. 
International Archives of Photogrammetry and Remote Sensing. Vol. XXXI, Part B5. Vienna 1996