Thesis (MNutr)--University of Stellenbosch, 2008. / Bibliography. Also available via the Internet.

Traditional three-dimensional (3D) photonic scanning (3DPS) can be used to obtain body volume data and to enable visualization of 3D body shape in one rapid scan, which is helpful for determining people’s obesity level, health risk and sport performance as well as motivating individuals to reduce weight efficiently. Nevertheless, traditional 3DPS is restricted to expensive and fixed hardware and specific software that requires specialist interpretation in laboratory settings, which reduces possible applications. Therefore, the purpose of this research was to develop a fast, inexpensive, portable and automatic 3DPS system to measure body volume data and to display body shape in 3D. To ensure that the system could be used for monitoring changes over time, the accuracy and reliability of the estimated body volumes were also established. Four studies and one technical description were conducted to achieve the purpose of this research. In the first three studies, a new technique, DScan, was developed that could generate individual 3D human models and calculate body volume. In Study 1, the reliability of the body dimension features obtained by four extraction methods was compared to find an appropriate method to improve the quality of extracted body dimension features. In Study 2, two different parameter groups were compared to enable subsequent selection of appropriate parameters to generate realistic 3D human models. A procedure and a program were presented which can set the parameters to match the extracted features and generate individual 3D human models effectively. In Study 3, Blender scripts and shell scripts were used to develop a customized program which can obtain body volume data from generated 3D human models. In Study 4, the accuracy and the reliability of the body volume data acquired from DScan were examined by comparing with the traditional 3DPS and the geometric modelling technique, elliptical zone (E-Zone). In the technical description, a Body Shape Monitoring System (BSMS) which can help non-expert users complete the DScan procedure and visualize body shape changes was introduced. The processing speed, cost and portability of the introduced BSMS were also shown in the technical description. The accuracy of the BSMS for whole-body volume indicated by an inter-method relative technical error of measurement was within 5% of that obtained from the traditional 3DPS. The repeated reliability expressed as an intra-method relative technical error of measurement was under 3% for whole-body volume. The accuracy and the reliability of the BSMS for segmental volumes (upper torso, lower torso, upper arm, lower arm, thigh and shank) indicated by inter-method and intra-method relative technical error of measurements were less than 10% and 5% respectively. These were similar to those obtained by the E-Zone. The BSMS reduces the requirement of hardware, software and expert knowledge as well as the processing time compared to other techniques of quantifying whole-body volume and segmental volumes. The GUI of the BSMS enables it to be used without specific training in computer programing or machine operation. The system is highly portable, and its components are inexpensive (under £700). Each analysis can be completed in three minutes without requiring subjective interpretations. The results showed that the system has the potential to be applied in the domains of health and medicine, the fashion industry, ergonomics, and sports science. Further studies should be conducted to develop a complete system which is consequently suitable for home use.

Made available in DSpace on 2016-03-15T19:41:25Z (GMT). No. of bitstreams: 1 Alisson Rogerio Caetano de Siqueira.pdf: 1217726 bytes, checksum: 1361665d59b670b77eeaf91912135a0b (MD5) Previous issue date: 2015-02-05 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / The aim of this study was to characterize the anthropometric profile of a group of people with Down syndrome (DS), establishing correlations between body mass index variables, waist circumference, waist-hip ratio, body fat percentage established as from the bioelectrical impedance and skinfold measurements, with the peak expiratory flow and sleep characteristics. The study included 63 individuals with DS, of both sexes with age between 11 to 25, linked to DS care institutions. Data was collected: weight, height, waist circumference, hip circumference, body fat percentage by bioelectrical impedance and skinfold, peak expiratory flow and sleep characteristics from the Children Sleep Habits Questionnaire administered to the parents of the participants. Data were analyzed using Pearson's correlation test. All body composition variables showed marked tendency to excessive concentration of body fat with strong correlation. Waist-hip ratio presented high levels for risk of developing coronary heart disease and correlation with body composition variables for males only. The peak expiratory flow had similar results to other studies on DS with lower values compared to people with normal development but the correlation between body composition variables performed for males only. The characteristics of sleep showed results that suggest presence of sleep disorders with a high number of individuals classified above the cut-off point but the correlation with the body composition variables were observed in women only. It is believed that the lack of studies, specific reference tests and rates for the DS population is an important factor that can directly interfere in the data analysis. No composition index should be used in isolation and all results should be treated with discretion and careful manners in order that they are not over or underestimated. / O objetivo deste estudo foi caracterizar o perfil antropométrico de um grupo de pessoas com síndrome de Down (SD), estabelecendo correlações entre as variáveis de índice de massa corporal (IMC), circunferência de cintura (CC), relação cintura-quadril (RCQ), percentual de gordura (%G) estabelecida a partir da bioimpedância (BIA) e das medidas de dobras cutâneas (DC), com o pico de fluxo expiratório (PFE) e características do sono. Participaram do estudo 63 indivíduos com SD, de ambos os sexos com faixa etária compreendida entre 11 e 25 anos, vinculados a instituições de assistência à pessoa com SD. Foram coletados dados de peso, estatura, CC, circunferência de quadril, DC, %G por meio da bioimpedância, PFE e características do sono a partir do questionário Children Sleep Habits Questionnaire aplicado aos pais dos participantes. Os dados foram analisados por meio do teste de correlação de Pearson. Todas as variáveis de composição corporal apresentaram importante tendência de excessiva concentração de gordura assim como forte correlação entre si. A RCQ apresentou elevados índices para risco de desenvolvimento de doença coronariana e correlação com variáveis de composição corporal apenas para o sexo masculino. O PFE apresentou resultados semelhantes a outros estudos com SD, evidenciando valores inferiores se comparados à população com desenvolvimento típico, porém a correlação entre as variáveis de composição corporal apenas se apresentou para o sexo masculino. As características do sono mostraram resultados que sugerem a presença de distúrbios do sono com número elevado de indivíduos classificados acima da nota de corte, no entanto a correlação com as variáveis de composição corporal somente foram observadas no sexo feminino. Acredita-se que a escassez de estudos, testes e índices de referência específicos para a população com SD é um importante fator que pode interferir de maneira direta na análise do dados. Nenhum índice de composição corporal deve ser utilizado de maneira isolada e todos os resultados devem ser analisados com critério e de maneira cuidadosa afim de que não sejam super ou subestimados.