iced image after 
uced from the Q 
ear closer to the 
)-referenced 3D Video 
or Cultural Heritage", 
TORIC BUILDINGS, 
ıd Modern Methods", 
sdam Germany, 18-21 
Defocus and Rapid 
roceedings of the IEEE 
uter Vision and Pattern 
992. pp. 773-776 
Focusing Techniques", 
No. 11, pp. 2824-2836, 
"using and defocusing", 
nd Pattern Recognition, 
perflib/ipl/iplperfspec. 
Automated Point Measurement of Dynamic Skin Membrane Surfaces Utilizing a Dot Projection Photogrammetric 
Technique 
Gary Robertson 
ShapeQuest Inc. Scottsdale Arizona USA 
Commission V 
Keywords: Automatic target reading, image processing, digital imagery, stereo matching, dot projection, dot target projection, 
synchronized digital cameras, digital image matching, real time measurement, dynamic measurement, static measurement, skin, skin 
membranes inflatable structures, vacuum chamber, pattern projector, forensic, imprint marks 
Abstract: 
This paper describes the development of a measurement system for measuring the shape of ultra-light and inflatable structural test 
articles. The system was designed to accommodate multiple computing with up to 12 time synchronized digital cameras and provide 
measurement accuracy of at least 1 part in 60,000. The system is capable of measuring both stationary (static) structures as well as 
nonstationary (dynamic or deploying) structures at a frame rate of at least 20 to 900 frames per minute for a continuous time period 
of at least 15 minutes. Measurements with this system are obtained with the faster, more-modern dot projection approach, rather than 
the slower, more-traditional approach of mounting an array of retro reflective targets on the structure. Also due to the surfaces of the 
inflatable thin membranes physical targets can not be used or be practical. Also discussed are the cameras used, lenses, calibration 
and projector system for working in a vacuum, discussion as to cooling and structural consideration for proper operation in a vacuum 
or other harsh environments is described. To meet the demand for near real time measurement in this magnitude required special 
hardware configurations and software integration and solutions in hardware as to provide near real time throughput. Integration of 
the digital cameras with the hardware to provide the current capability of camera output of 15 frames per second, the ability of 
reading projected dot patterns of at least 4000 points automatically and to perform stereo matching. The time to open the camera 
files measure the projected targets (up to 4000) compute the coordinate and close the file are within two seconds. So for practical 
purposes it could be considered in real time. Discussion will be made to describe the measurement of these light inflatable membrane 
structural test articles. We also discuss the issue of dot projection on membrane surfaces, colors, and translucent materials. In 
addition we will discuss the comparisons and similarity of human skin to these light membranes. This research is applied for forensic 
research to monitor the lapse rate of human skin indention. The paper will provide project results from the NASA skin membrane 
test and human skin membranes. 
1.0 INTRODUCTION 
Surface measurement of thin membrane material and skin 
presents interesting problems with targeting especially if it is a 
dynamic event. Dot target projection provides in some cases 
the only reasonable approach for measurement. In particular 
any object surface that does not lend itself for target placement, 
such as skin, clear or thin skin membranes, or dynamic process. 
The projection of targeting has been used with great success 
over the years as reported in (Robertson 1986,1988). In fact dot 
target projection can and is used for measurement and 
modeling of most surfaces. This avoids the time consuming 
placement of retro reflective targets and the placement and 
specifically alignment of the corresponding light source 
required for retro targets. 
   
Figure 1 Flat membrane surface Figure 3 uniform surfaces 
—79—