An Anthropometric Analysis of Seated and Standing People
4.3 Methodologies for the Determination of Various Relevant Anthropometric Parameters
4.3.4 Practical Methods and Techniques for the Projected Area Factors
The projected area factor in a given direction is defi ned as the ratio between the area of a human body projected onto a plane perpendicular to the direction, A p , and the effective radiating area of the body, A r :
p p r
f A
= A (4.32)
Regarding its determination, two kinds of methods are currently available: experimental meth- ods, based on actual measured values of the project area of the human body, and numerical simula- tion methods, based on the reconstruction of the 3D human body numerical model.
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4.3.4.1 Experimental Methods
Several experimental methods have been assessed over recent years in an attempt to measure the projected areas of standing and seated people, by means of photographic methods (Guibert and Taylor 1952 ; Underwood and Ward 1966 ; Fanger 1970 ; Calvino et al. 2005 ; Calvino et al. 2009 ) . These consist of photographing the subject from many directions, with each photograph providing the project area of the body for a given viewing angle. When the project area of the body is known for an adequately large number of angles, all radiation data for the body can be calculated (Fanger 1970 ) . Fanger applied this method to a Scandinavian panel of ten men and ten women. The apparatus employed six mirrors in fi xed positions, at steps of 15°, and a movable mirror (see Fig. 4.1 ). The body (subject) is placed on a platform that can be pivoted around a vertical axis and elevated. By turning the movable mirror, the subject can be photographed with a fi xed camera from six different angles (altitude b ) on a vertical plane (six mirrors). By rotating the platform 15° at a time, a total of 13 horizontal angles (azimuth a ) can be investigated. In total, 78 exposures (i.e., 13 × 6) within a quarter sphere are obtained, the measurement of which is suffi cient due to the right/left symmetry of the body, and because the projected area from any two opposite directions is the same. Projected areas, A p ( a , b ), were then obtained by means of double planimeter.
Once the values of the projected areas, A p , are obtained, it is possible to deduce the effective radiating area, A r , and the projected area factor, f p ( a , b ), as a function of the azimuth and zenith angles. The last parameter is defi ned as the ratio between the projected area, A p ( a , b ), and the effec- tive radiating area of the human body, as described in (4.32) .
The data of the projected area factor provided by Fanger are reported in Fig. 4.2 (Fanger 1970 ) , for standing and seated postures; these data are currently used in ergonomic evaluations.
In order to take more pictures of subjects at smaller angle steps and verify Fanger’s original data for non-Scandinavian people, we have designed and constructed a photographic platform at the Dipartimento dell’Energia of the Università degli Studi di Palermo (Calvino et al. 2005 ) . A proce- dure for managing the digital images of the human body has been assessed, taking into account the measurement of people’s projected areas in standing and seated postures at various azimuth and zenith angles.
This experimental apparatus can be classifi ed as a single viewpoint method (Roebuck et al. 1975 ) . It is composed (see Fig. 4.3 ) of an anthropometer, scales, mechanical equipment, optical apparatus, and a system for producing images.
The optical apparatus comprises a digital camera which is linked to a PC, the aim of which is to generate images and process them with appropriate software. The camera has been selected due to its compatibility with the computer, its graphical resolution, and is capacity to be remotely controlled.
The digital camera comprises the camera’s objective and the optical sensor; the former is required to reach a compromise between the minimization of the optical distortion of the image and the length of the jib (Calvino et al. 2005 ) . After the images are produced, they are suitably edited to remove objects unrelated with the shape of people being measured. In order to remove any undesired color intensity, which could lower the contrast level of the image, the images are subjected to a fi ltering process. They are then converted into a gray scale to enhance the manageability of the elaboration process. Finally, the images are converted from the gray to a black and white scale, as shown in Fig. 4.4 .
The fi nal step is the computation of the projected area of the subject and this is accomplished by simply counting the black pixels. To convert the values of these data from the number of pixels to surface area (m 2 ), they are multiplied by the proper conversion factor obtained by the measurement of a sample image, which refers to an object of known dimensions. Starting from the statistical analysis of the anthropometric characteristics of a given group of people, it is now possible to address measurements of projected areas pertaining to subjects statistically representative of this group.
101 4 An Anthropometric Analysis of Seated and Standing People
Fig. 4.2 Projected area factors for standing ( left ) and seated ( right ) people. By the values of the projected areas, obtained with experimental methods, it is possible to deduce the projected area factor. The results reported, provided by Fanger for standing and seated postures, are currently used in ergonomic evaluations
Fig. 4.1 Description of the photographic method utilized by Fanger. The experimental method assessed by Fanger consists of photographing the subject from several directions; the apparatus employed six mirrors in fi xed positions, at steps of 15°, and a movable mirror. The subject is placed onto a platform, which can be pivoted around a vertical axis as well as being elevated
Calvino et al. ( 2009 ) have selected the subjects whose weight and height values fall within the 10th and the 90th percentiles, with respect to statistical data for the southern Italian population. Table 4.3 shows these limit values for male and female subjects.
The mean values of the projected area factors, f p , for standing and seated people have been evalu- ated; they are shown in Fig. 4.5 .
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4.3.4.2 Numerical Simulation Methods
One of the fi rst researchers to propose a new numerical simulation method for predicting the effective radiating area and the project area of the human body for any posture was Tanabe (Tanabe et al. 2000 ) . This method is based on the solar gain simulation, as proposed by Ozeki et al. ( 1992 , 1997 ), according to which body shape was obtained by means of commercially available software and divided into 4,396 quadrilateral surface elements, for both standing and seated postures. To derive the project area of the human body, they utilized the parallel ray method introduced by Fanger ( 1970 ) : “this project area is equal to the surface area of the human body where parallel rays reach directly and which is projected onto a plane perpendicular to the parallel rays” (Tanabe et al. 2000 ) . The projected area is evaluated by utilizing both surface elements A i and incident angles q i of the parallel rays to the surface elements.
Thus, the projected area A p of the human body is obtained by means of the following equation:
p =
∑
i icosθii
A g A (4.33)
where g i indicates whether a parallel ray reaches the surface element ( g i = 1) or not ( g i = 0). The algorithm utilized for calculating the project area of a human body is shown in Fig. 4.6 .
Tanabe et al. ( 2000 ) applied the algorithm, in Fig. 4.6 , to 91 directions of the ray (13 × 7), 13 values of the azimuth angle and seven values of the zenith angle. They utilized (4.27) to evaluate the
Fig. 4.3 Experimental apparatus. The experimental apparatus realized at the Dipartimento dell’Energia of the Palermo University is composed of an anthropometer, scales, mechanical equipment, optical apparatus, and a system for producing images
103 4 An Anthropometric Analysis of Seated and Standing People
effective radiation area. Finally, they divided the obtained projected area by the effective radiating area to evaluate the project area factor (see Fig. 4.7 ).
Another study that utilized a numerical simulation method is that of Lo Curcio ( 2009 ) , who also utilized commercially available software (Poser ® ) to obtain a body-shape digital model and to photo- graph it from several viewing angles with a virtual camera; he thus simulated the photographic method utilized by Fanger. The algorithm utilized for calculating the projected area of a human body is shown in Fig. 4.8 .
Lo Curcio applied this algorithm to 12 body shape models (six male and six female) from Italy, Australia and Britain, China, Japan, Germany, and the United States (see Fig. 4.9 ).
The main anthropometric characteristics of these body shape models are reported in Table 4.4 . Figure 4.10 shows the projected area factors of standing (left) and seated (right) people, referring to the Italian male sample, obtained by Lo Curcio ( 2009 ) .
Fig. 4.4 Starting from the actual image, the gray and black-and-white scales. The images are suitably edited to remove objects unrelated and any undesired color intensity; then they are converted into a grey scale and fi nally to a black and white scale
Table 4.3 Weight and height values, corresponding to 10th and 90th percentiles for male (subscript M) and female (subscript F) subjects of the southern Italian population
Percentiles (%)
Weight M (kg)
Weight F (kg)
Height M (cm)
Height F (cm)
10 62 50 161 153
90 90 79 180 169
This table reports the limit values (10th and 90th percentiles) of weight and height for male and female subjects, with respect to statistical data for the southern Italian population, within which Calvino et al.
( 2009 ) have selected the subjects
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Fig. 4.5 Projected area factors of standing ( left ) and seated ( right ) people referring to the southern Italian population (Calvino et al. 2009 ) . Calvino and his co-workers, have evaluated the mean values of the projected area factors, for standing and seated people, selecting the subjects whose weight and height values fall within the 10th and the 90th percentiles, with respect to statistical data for the southern Italian population
Fig. 4.6 Algorithm for calculating project area of the human body (Tanabe et al. 2000 ) . The Tanabe numerical simu- lation method for predicting the effective radiating area and the project area of the human body (Tanabe et al. 2000 ) is based on the solar gain simulation, according to which body shape, obtained by means of commercially available software, is divided into quadrilateral surface elements