https://www.cs.ucla.edu/~dt/papers/mia96/mia96.pdf

Deformable models in medical image analysis: a survey

In recent years, many shape representations and geometric algorithms have been proposed for matching 3D shapes. Usually, each algorithm is tested on a different (small) database of 3D models, and thus no direct comparison is available for competing methods. We describe the Princeton Shape Benchmark (PSB), a publicly available database of polygonal models collected from the World Wide Web and a suite of tools for comparing shape matching and classification algorithms. One feature of the benchmark is that it provides multiple semantic labels for each 3D model. For instance, it includes one classification of the 3D models based on function, another that considers function and form, and others based on how the object was constructed (e.g., man-made versus natural objects). We find that experiments with these classifications can expose different properties of shape-based retrieval algorithms. For example, out of 12 shape descriptors tested, extended Gaussian images by B. Horn (1984) performed best for distinguishing man-made from natural objects, while they performed among the worst for distinguishing specific object types. Based on experiments with several different shape descriptors, we conclude that no single descriptor is best for all classifications, and thus the main contribution of this paper is to provide a framework to determine the conditions under which each descriptor performs best.

/pdf/the-princeton-shape-benchmark-2gmwi9i096.pdf

The Princeton Shape Benchmark

BackgroundLung auscultation and bedside chest radiography are routinely used to assess the respiratory condition of ventilated patients with acute respiratory distress syndrome (ARDS). Clinical experience suggests that the diagnostic accuracy of these procedures is poor.MethodsThis prospective study

Comparative Diagnostic Performances of Auscultation, Chest Radiography, and Lung Ultrasonography in Acute Respiratory Distress Syndrome

Recent developments in techniques for modeling, digitizing and visualizing 3D shapes has led to an explosion in the number of available 3D models on the Internet and in domain-specific databases. This has led to the development of 3D shape retrieval systems that, given a query object, retrieve similar 3D objects. For visualization, 3D shapes are often represented as a surface, in particular polygonal meshes, for example in VRML format. Often these models contain holes, intersecting polygons, are not manifold, and do not enclose a volume unambiguously. On the contrary, 3D volume models, such as solid models produced by CAD systems, or voxels models, enclose a volume properly. This paper surveys the literature on methods for content based 3D retrieval, taking into account the applicability to surface models as well as to volume models. The methods are evaluated with respect to several requirements of content based 3D shape retrieval, such as: (1) shape representation requirements, (2) properties of dissimilarity measures, (3) efficiency, (4) discrimination abilities, (5) ability to perform partial matching, (6) robustness, and (7) necessity of pose normalization. Finally, the advantages and limitations of the several approaches in content based 3D shape retrieval are discussed.

/pdf/a-survey-of-content-based-3d-shape-retrieval-methods-1p1e9hurpn.pdf

A survey of content based 3D shape retrieval methods

The American Thoracic Society/European Respiratory Society jointly created a Task Force on "Outcomes for COPD pharmacological trials: from lung function to biomarkers" to inform the chronic obstructive pulmonary disease research community about the possible use and limitations of current outcomes and markers when evaluating the impact of a pharmacological therapy. Based on their review of the published literature, the following document has been prepared with individual sections that address specific outcomes and markers, and a final section that summarises their recommendations.

/pdf/outcomes-for-copd-pharmacological-trials-from-lung-function-4a4k924y7q.pdf

Outcomes for COPD pharmacological trials: From lung function to biomarkers

We present in this paper a generic algorithm to compute the skeleton of an n-dimensional binary object. Considering the cartesian hypercubic grid, we provide a mathematical framework in which are given the explicit Boolean conditions under which the iterative thinning procedure removes a point. This algorithm preserves the topology in a sense which matches the properties usually used in 2D and 3D. Furthermore, it is based on an original kind of median hypersurface that gives to the skeleton good behavior with respect to both shape preservation and noise sensitivity. The algorithm is fully parallel, as no spatial subiterations are needed. The latter property, together with the symmetry of the boolean n-dimensional patterns leads to a perfectly isotropic skeleton. The logical expression of the algorithm is extremely concise, and in 2D, a large comparative study shows that the overall number of elementary Boolean operations needed to get the skeleton is smaller than for the other iterative algorithms reported in the literature.

/pdf/unified-mathematical-framework-for-a-compact-and-fully-1z15uyqd27.pdf

Unified mathematical framework for a compact and fully parallel n-D skeletonization procedure

We present a skeletonization algorithm defined by ex- plicit Boolean conditions which are dimension independent. The pro- posed procedure leads to new thinning algorithms in two dimen- sions (2D) and three dimensions (3D). We establish the mathematical properties of the resulting skeleton referred to as the MB skeleton. From a topological point of view, we prove that the algorithm preserves connectivity in 2D and 3D. From a metric point of view, we show that the MB skeleton is located on a median hy- persurface (MHS) that we define. This MHS does not correspond to the standard notion of median axis/surface in 2D/3D, as it combines the various distances associated with the hypercubic grid. The MHS specificities prove to make the skeleton robust with respect to noise and rotation. Then we present the algorithmic properties of the MB skeleton: First, the algorithm is fully parallel, which means that no spatial subiterations are needed. This property, together with the symmetry of the Boolean n-dimensional patterns, leads to a per- fectly isotropic skeleton. Second, we emphasize the extreme con- ciseness of the Boolean expression, and derive the computational efficiency of the procedure. © 2002 SPIE and IS&T.

n-dimensional skeletonization: a unified mathematical framework

Multidetector computed tomography (MDCT) acquisition during a single breath hold using thin collimation provides high resolution volumetric data set permitting multiplanar and three dimensional reconstruction of the proximal airways. In chronic obstructive pulmonary disease (COPD) patients, this technique provides an accurate assessment of bronchial wall thickening, tracheobronchial deformation, outpouchings reflecting dilatation of the submucous glands, tracheobronchomalacia, and expiratory air trapping. New software developed to segment adequately the lumen and walls of the airways on MDCT scans allows quantitative assessment of the airway dimensions which has shown to be reliable in clinical practice. This technique can become important in longitudinal studies of the pathogenesis of COPD, and in the assessment of therapeutic interventions.

/pdf/investigation-of-airways-using-mdct-for-visual-and-2wps3tv6iz.pdf

Investigation of airways using MDCT for visual and quantitative assessment in COPD patients.

This paper presents first compression results on using the MPEG-4 BBA standard for encoding motion capture data. We first introduce a detailed description of the main compression mechanisms used in recently BBA standard: prediction, frequency transform, quantization and entropy encoder and discuss the theoretical range of encoding performances. Then we introduce an optimized BBA encoder including also a key-frame reduction mechanism and show the compression results on animation files from typical motion capture data-base. We compare the results with the ones reported in literature showing the advantages of the MPEG-4 BBA in terms of bit-rate, complexity and range control.

Optimized MPEG-4 animation encoder for motion capture data

The MPEG-4 face and body animation (FBA) specifications aims at standardizing an interchange format for specifying virtual face and body modeling and related animation parameters. The scene graph concept, the FBA nodes, semantics and representation of the animation parameters as well as compression and streaming capabilities are successively addressed. The compatibility between virtual character animation techniques and MPEG-4 FBA is analyzed in terms of modeling, deformation behavior and animation capabilities.

Francoise Preteux

Papers

Unified mathematical framework for a compact and fully parallel n-D skeletonization procedure

n-dimensional skeletonization: a unified mathematical framework

Investigation of airways using MDCT for visual and quantitative assessment in COPD patients.

Optimized MPEG-4 animation encoder for motion capture data

Critic review on MPEG-4 face and body animation