- METHODOLOGY FOR POROSIMETRY IN VIRTUAL CEMENTITIOUS COMPOSITES TO ECONOMICALLY AND RELIABLY ESTIMATE PERMEABILITY
Kai Li, Piet Stroeven, Nghi LB Le
A novel methodology is described for porosimetry as well as for water transport through the pore system in dynamic DEM-based virtual cementitious materials. The pore network topology, the pore size distribution and the pore connectivity are assessed on the basis of a robotics-inspired pore delineation method and star volume measurements. Permeability estimates are based on a tube network model that incorporates these parameters and a shape factor. Since concrete contains in practical situations a variable amount of water, permeability estimation is presented as a function of the state of saturation. Satisfactory agreement is found with experimental data, validating the methodology. Earlier, the various "building blocks" were separately validated.
- COLUMN TESSELLATIONS
Linh Ngoc Nguyen, Viola Weiss, Richard Cowan
A new class of non facet-to-facet random tessellations in three-dimensional space is introduced — the so-called column tessellations. The spatial construction is based on a stationary planar tessellation; each cell of the spatial tessellation is a prism whose base facet is congruent to a cell of the planar tessellation. Thus intensities, topological and metric mean values of the spatial tessellation can be calculated from suitably chosen parameters of the planar tessellation.
- FLOWING BILATERAL FILTER: DEFINITION AND IMPLEMENTATIONS
Maxime Moreaud, François Cokelaer
The bilateral filter plays a key role in image processing applications due to its intuitive parameterization and its high quality filter result, smoothing homogeneous regions while preserving the edges of the objects. Considering the image as a topological relief, seeing pixel intensities as peaks and valleys, we introduce a way to control the tonal weighting coefficients, the flowing bilateral filter, reducing "halo" artifacts typically produced by the regular bilateral filter around a large peak surrounded by two valleys of lower values. In this paper we propose to investigate exact and approximated versions of CPU and parallel GPU (Graphical Processing Unit) based implementations of the regular and flowing bilateral filter using the NVidia CUDA API. Fast implementations of these filters are important for the processing of large 3D volumes up to several GB acquired by x-ray or electron tomography.
- MATHEMATICAL MORPHOLOGY BASED CHARACTERIZATION OF BINARY IMAGE
Raghvendra Sharma, B. S. Daya Sagar
This paper reports the results of a theoretical study on morphological characterization of foreground (X) and background (Xc) of a discrete binary image. Erosion asymmetry and dilation asymmetry, defined to elaborate smoothing of an image respectively by contraction and expansion, are generalized for multiscale smoothing, and their relationships with morphological skeleton and ridge (background skeleton) transformations are discussed. Then we develop algorithms identifying image topology in terms of critical scales corresponding to close-hulls and open-skulls, along with a few other salient characteristics, as respective smoothing by expansion and contraction proceeds. For empirical demonstration of these algorithms, essentially to unravel the hidden characteristics of topological and geometrical relevance, we considered deterministic and random binary Koch quadric fractals. A shape-size based zonal quantization technique for image and its background is introduced as analytical outcome of these algorithms. The ideas presented and demonstrated on binary fractals could be easily extended to the grayscale images and fractals.
- A MIXED BOOLEAN AND DEPOSIT MODEL FOR THE MODELING OF METAL PIGMENTS IN PAINT LAYERS
Enguerrand Couka, François Willot, Dominique Jeulin
Pigments made of metal particles of around 10 µm or 20 µm produce sparkling effects in paints, due to the specular reflection that occurs at this scale. Overall, the optical aspect of paints depend on the density and distribution in space of the particles. In this work, we model the dispersion of metal particles of size up to 50 µm, visible to the eyes, in a paint layer. Making use of optical and scanning electron microscopy (SEM) images, we estimate the dispersion of particles in terms of correlation functions. Particles tend to aggregate into clusters, as shown by the presence of oscillations in the correlation functions. Furthermore, the volume fraction of particles is non-uniform in space. It is highest in the middle of the layer and lowest near the surfaces of the layer. To model this microstructure, we explore two models. The first one is a deposit model where particles fall onto a surface. It is unable to reproduce the observed measurements. We then introduce a "stack" model where clusters are first modeled by a 2D Poisson point process, and a bi-directional deposit model is used to implant particles in each cluster. Good agreement is found with respect to SEM images in terms of correlation functions and density of particles along the layer height.
- QUANTITATIVE APPROACH TO ASSIST NEUROBLASTOMA ASSESSMENT BY MEASURING I-123 mIBG UPTAKE IN SCINTIGRAPHIC IMAGES
Rafael Martínez-Díaz, Julia Balaguer, Luis Manuel Sánchez-Ruiz, Pilar Bello, Victoria Castel, Antonio Rivas, Adela Cañete, Marina Falgas, Jose Luis Loaiza, Guillermo Perís-Fajarnés
Whole-body 123I-Metaiodobenzylguanidine (mIBG) scintigraphy is used as the primary image modality in neuroblastoma detection. It is the most sensitive and specific method for staging and response evaluation. Validated semi-quantitative scoring methods with low interobserver variability and high reproducibility have shown to be indispensable for the evaluation of response to therapy. However, low resolution, noise and acquisition difficulties, specially in children, make low definition scans. These facts increase observer dependent interpretations that limit assessment and complicate to put a scoring method successfully into practice. It is essential to have an objective and reliable measure of response to test the activity of therapies. In this paper we propose the use of a quantitative observer-independent measurement of the strength of uptake to be used as an additional tool for assisting the International Society of Paediatric Oncology Europe Neuroblastoma Group (SIOPEN) semi-quantitative scoring method. This is the scoring method recommended by the SIOPEN Nuclear Medicine and Physics Committee, in collaborative work with the Children’s Oncology Group, as the standard one for acquiring and reporting diagnostic paediatric mIBG scans across Europe. Our proposed method is based on the ratio between the amount of specific uptake at tumours and the amount of non-specific uptake at SIOPEN anatomical sectors which has shown to be constant in all the scans of the patients.
- CORRIGENDUM: MEAN VALUES FOR HOMOGENEOUS STIT TESSELATIONS IN 3D (2008 IMAGE ANAL STEREOL 27:29-37)
Werner Nagel, Viola Weiss
Corrigendum of MEAN VALUES FOR HOMOGENEOUS STIT TESSELLATIONS IN 3D (2008 IMAGE ANAL STEREOL 27:29–37)