A new technique for three-dimensional measurements of skin surface contours: evaluation of skin surface contours according to the ageing process using a stereo image optical topometer

Abstract

The evaluation of skin surface contours can be carried out by various techniques, including the use of a stylus profilometer, a laserprofilometer and a conventional optical profilometer (COP). But these methods have some drawbacks because their data are basically obtained from two-dimensional algorithms. So a new technique has been developed based on a new concept: a stereo image processing technique which is considered in this paper. Since a pair of stereo images contains depth information, the 'disparity', or the difference between the left and right images, enables the production of three-dimensional coordinates. This study was performed to evaluate the change of skin surface contours according to the ageing process. The stereo image optical topometer (SOT) is a new instrument used for the three-dimensional evaluation of skin surface contours. Thus. five new parameters have to be developed, such as mean surface roughness (S(a)), mean depth of roughness (S(z)), three-dimensional length (S(L)), three-dimensional area (S(A)), and three-dimensional volume (S(V)). S(a), S(L) and S(A) have shown a statistically significant increase in the seventies age group. S(z) has also shown a significant increase in the twenties and over-sixties age groups. The coefficient variation of the height of the skin surface using a COP varies between 14.76 and 6.57, but that using a SOT is between 2.18 and 2.69, according to age variation. In conclusion, the SOT system is a more reliable and useful method for evaluating skin surface contours than the COP system. Among the three-dimensional parameters which were made in this study, S(A), S(L) and S(a) seem to be useful as reliable parameters for evaluating skin surface contours in the ageing process.

Objective interpretation of severity of SLS induced edema by stereoimaging

“…However, unlike COP, SOT calculates the values of S a and S z using entirely image data, which is obtained by measuring 468 horizontal lines per measurement realistically reflect the contours of the skin surface. In an experiment on changes in skin furrowing versus aging which utilized these five parameters, skin furrow changes were found to be statistically significant for each 3D parameter [15].…”

“…Disparity data contains information on height measured from not only from the original x and y coordinates but also of the z co-ordinate--the height. Thus, this 3D information can be easily calculated and used to study characteristic skin surface contours [15][16][17][18].…”

“…In terms of the validity and reliability test of SOT as applied in dermatological field, Oh and co-workers [15], reported that the significantly smaller coefficient variation of R z calculated using SOT as compared with COP, demonstrated that SOT is much more reliable than COP. Moreover, SOT is capable of analyzing skin surface contours 3-dimensionally, though new 3D parameters were required to create this 3D data.…”

“…Thus, this 3D information can be readily calculated and used to study characteristic skin surface contours [15][16][17][18]. Validity and reliability test were performed by Oh et al [15].…”

“…In the present study, we quantitatively measured the morphologic changes of skin surface contours in SLS-induced edema by using a stereoimaging optical topometer (SOT), as developed by Oh and co-workers [15], which directly obtains 3D data and evaluates skin surface contours. Five parameters of these morphological changes were analyzed and compared with visual scorings to determine the possibility of applying SOT to evaluate the severity of SLS-induced edema objectively and quantitatively.…”