3D Mesh Extraction for Transmission Line Matrix Modelling
The ModaVox program was developed to study acoustic propagation of vowel sounds in a 3D vocal tract by using the transmission line matrix (TLM) method. The name ModaVox stands for “Modelador da Voz” in Portuguese, or Voice Modeler in English. At the prese
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Abstract The ModaVox program was developed to study acoustic propagation of vowel sounds in a 3D vocal tract by using the transmission line matrix (TLM) method. The name ModaVox stands for ‘‘Modelador da Voz’’ in Portuguese, or Voice Modeler in English. At the present moment, it is able to build and solve 3D TLM numerical models of the vocal tract. The meshes are constructed over the voxels (volumetric picture elements) in segmented medical image sequences. The segmentation of the images is performed via a neural network, island removal and some manual adjustments with the ModaVox’s toolboxes. An implementation of the TLM method allows for the simulation of the acoustic propagation of the input signal through the TLM mesh of the vocal tract model. ModaVox also generates tetrahedral and or surface triangle meshes.
A. S. Brandão Mechanical Engineering Post-Graduation Program, Universidade Federal Fluminense, Rua Passo da Pátria 156, Bloco E, sala 216, CEP, São Domingos Niterói, RJ 24210-240, Brazil e-mail: [email protected] F. R. Leta Mechanical Engineering Department, Mechanical Engineering Post-Graduation Program, Universidade Federal Fluminense, Rua Passo da Pátria, 156, bloco D, sala 302, São Domingos, Niterói, RJ 24210-240, Brazil e-mail: [email protected] E. Cataldo (&) Applied Mathematics Department, Post-Graduation Program in Telecommunications Engineering, Universidade Federal Fluminense, Rua Mário Santos Braga, S/N Valonguinho, Niterói, RJ 24.020-140, Brazil e-mail: [email protected]
A. Öchsner et al. (eds.), Design and Analysis of Materials and Engineering Structures, Advanced Structured Materials 32, DOI: 10.1007/978-3-642-32295-2_12, Ó Springer-Verlag Berlin Heidelberg 2013
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1 Introduction Mesh extraction is an important step in any numerical scheme. Among the several existent 3D mesh extraction techniques, none is devoted to the extraction of meshes for the TLM method. Most of them are dedicated to extract tetrahedral or hexahedral meshes [1–3] for the finite element method (FEM) or surface meshes consisting of triangles [4] (or quadrilaterals) for the boundary element method (BEM). Despite 3D TLM models can be seen in several works [5, 6], their geometry tends to be rather rectangular, because the problem of mesh generation for 3D TLM meshes has not been addressed yet. For example, the TLM model in [6] consists of a 3D vocal tract model represented by a sequence of ducts with rectangular cross-sectional areas, whose values were obtained by magnetic resonance images (MRI) measurements. This chapter presents a simple mesh extraction technique, which uses the 3D grid structure formed by the voxels (volumetric picture elements) of a segmented object in a 3D image to build the edges and nodes of a 3D TLM mesh. The technique is implemented in the ModaVox (an open source software developed during this research) and will be explained and demonstrated in synthetic 3D images forming tube concatenation models of the vocal tract and also in a 3D MRI sequence of a real human vo
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