Morphometric Methods Of Biological Forms Via Outline-fitting

Morphometry is the investigation of quantitative analysis to compare morphometric differences between a group of samples,and it is one of the most significant tools for the research of biological sciences,archaeology and medicine and anatomy.Researchers propose different morphometric methods to interpret different forms of samples,to focus the field of view on the specimen itself or to reconstruct the profile of the sample.Thus the morphometric methodologies play an important role in related researches.The methods of outline-based mopgometric are extended and the main work and conclusions are as follows.Two methods to fit and analyze profiles of samples are improved.First,a new method based on dynamic circular epicycles for fitting and analyzing two-dimensional closed contours is employed to solve the defects in the traditional Fourier method.Discrete time Fourier transform(DTFT)is presented and applied to the fitting of two-dimensional closed contours.By transforming the geometric parameters of the circles,the influence of sample position,orientation and size on the morphometric analysis is eliminated.Second,discrete cosine transform(DCT)in signal processing is introduced.We make classification of two-dimensional open profiles performed with DCT based on current morphometric investigations,the sample profiles need to be aligned to exclude the influence of non-shape factors before approximated.At the same time,the DCT method is extended to the analysis of three-dimensional open profiles,bridging the gap in the morphometric research of three-dimensional profiles.In addition,the shape-changing chain method is also introduced and improved to conduct shape representation and morphometric analysis.The shape-changing chain method employs a series of segments with particular properties to approximate the sample profile and achieve curve fitting and analysis with fewer parameters.In the fitting process,M-segment,H-segment(C-segment)and Gsegment are employed in combination to approximate different sample profiles.Segmentation strategies based on the geometric and biological characteristics of the profiles are also used to reduce the errors generated during the fitting process and to improve the reliability of morphometric analysis.In the shape-changing chain method,the relative angles between different segments or the unit direction vectors of the segments are used as variables for morphometric analysis.The variables generated in the shape-changing chain method reflect the geometric characteristics and physical significance of the sample profiles.Finally,these above three methods are applied to different biological samples for fitting and morphometric analysis to verify the validity and stability of themselves.The DCE method is adopted to fit and standardize the closed contours of the corpus callosum in human brain,the closed contours of ancient human mandibles and the leaf profiles;the DCT method is used to fit the spatial spiral curves and the 3D open cranial sutures;the shape-changing chain method is employed to match the open contours of ancient human mandibles,the closed leaf profiles and the 3D cranial sutures.The parameters in the fit results are analyzed by principal component analysis(PCA),discriminant analysis(DA)and between-group principal component analysis(bg PCA),respectively.Some of the above methods are also compared with the other ones and the results of these analyses demonstrate that all three methods are valid and stable in the corresponding morphometric applications.