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Discrete curvature calculation for fast level set segmentation
Kybic, Jan; Krátký, Jakub
2009 -
Fast level set methods replace continuous PDEs by a discrete formulation, improving the execution times. The regularization in fast level set methods was so far handled indirectly via level set function smoothing. We propose to incorporate standard curvature based regularization into fast level set methods and address the problem of efficiently estimating local curvature of a discretized interface in 2D or 3D based on local partial volume. We present two algorithms for incremental partial volume evaluation: the first is recommended for moderate neighborhood sizes, the second has an excellent asymptotic complexity and can be useful for very large neighborhoods. The performance of the proposed methods is compared experimentally with previous approaches.
Keywords:
image segmentation; level sets; curvature estimation
Available in digital repository of ČVUT.
Discrete curvature calculation for fast level set segmentation
Fast level set methods replace continuous PDEs by a discrete formulation, improving the execution times. The regularization in fast level set methods was so far handled indirectly via level set ...
Impedance of Adhesive Joints
Mach, Pavel; Kolář, Jiří
2009 -
Impedance of adhesive joints has been measured in frequency range 20 Hz - 1 MHz using LCR meter HP 4284A. The joints have been created by adhesive assembly of jumpers on test PCBs. It has been found that the joint impedance increases at the frequency higher than 100 kHz. It has been found that the measured frequency characteristics are in correlation with frequency characteristic of an equivalent circuit diagram consisting of in-series connected resistor and inductor.
Available in digital repository of ČVUT.
Impedance of Adhesive Joints
Impedance of adhesive joints has been measured in frequency range 20 Hz - 1 MHz using LCR meter HP 4284A. The joints have been created by adhesive assembly of jumpers on test PCBs. It has been found ...
Online learning of robust object detectors during unstable tracking
Kalal, Zdenek; Matas, Jiří; Mikolajczyk, Krystian
2009 -
This work investigates the problem of robust, longterm visual tracking of unknown objects in unconstrained environments. It therefore must cope with frame-cuts, fast camera movements and partial/total object occlusions/dissapearances. We propose a new approach, called Tracking-Modeling-Detection (TMD) that closely integrates adaptive tracking with online learning of the object-specific detector. Starting from a single click in the first frame, TMD tracks the selected object by an adaptive tracker. The trajectory is observed by two processes (growing and pruning event) that robustly model the appearance and build an object detector on the fly. Both events make errors, the stability of the system is achieved by their cancellation. The learnt detector enables re-initialization of the tracker whenever previously observed appearance reoccurs. We show the real-time learning and classification is achievable with random forests. The performance and the long-term stability of TMD is demonstrated and evaluated on a set of challenging video sequences with various objects such as cars, people and animals.
Available in digital repository of ČVUT.
Online learning of robust object detectors during unstable tracking
This work investigates the problem of robust, longterm visual tracking of unknown objects in unconstrained environments. It therefore must cope with frame-cuts, fast camera movements and partial/total ...
Line filtering for detection of microtools in 3D ultrasound data
Uherčík, Marián; Kybic, Jan; Cachard, Christian; Liebgott, Hervé
2009 -
We propose a robust method for localization of elongated surgical tools in 3D ultrasound data based on shape analysis. The tubular structures in input data are enhanced by a line filter in the pre-processing phase. A new model of a surgical tool appearance in 3D ultrasound image is proposed which exploits its tubular shape. The tool axis is estimated with robust model fitting using a randomized RANSAC procedure. The tool model requires the voxels close to the axis to have a high intensity, high tubularness, and the local principal directions to be consistent with the tool axis. The visual contrast of the tool can be enhanced four-fold using line filtering. We demonstrate that classification rate is improved by 25-40% when adding the tubularness attribute. The comparison to other state-of-the-art localization methods shows that the proposed method is the most robust for data with high level of noise at the expense of additional time for pre-processing (less than 10 seconds for volume of size 53×71×260 voxels).
Available in digital repository of ČVUT.
Line filtering for detection of microtools in 3D ultrasound data
We propose a robust method for localization of elongated surgical tools in 3D ultrasound data based on shape analysis. The tubular structures in input data are enhanced by a line filter in the ...
Geometric min-Hashing: Finding a (Thick) Needle in a Haystack
Chum, Ondřej; Perd’och, Michal; Matas, Jiří
2009 -
We propose a novel hashing scheme for image retrieval, clustering and automatic object discovery. Unlike commonly used bag-of-words approaches, the spatial extent of image features is exploited in our method. The geometric information is used both to construct repeatable hash keys and to increase the discriminability of the description. Each hash key combines visual appearance (visual words) with semi-local geometric information. Compared with the state-of-the-art min-hash, the proposed method has both higher recall (probability of collision for hashes on the same object) and lower false positive rates (random collisions). The advantages of geometric min-hashing approach are most pronounced in the presence of viewpoint and scale change, significant occlusion or small physical overlap of the viewing fields. We demonstrate the power of the proposed method on small object discovery in a large unordered collection of images and on a large scale image clustering problem.
Available in digital repository of ČVUT.
Geometric min-Hashing: Finding a (Thick) Needle in a Haystack
We propose a novel hashing scheme for image retrieval, clustering and automatic object discovery. Unlike commonly used bag-of-words approaches, the spatial extent of image features is exploited in our ...
Efficient Representation of Local Geometry for Large Scale Object Retrieval
Perd’och, Michal; Chum, Ondřej; Matas, Jiří
2009 -
State of the art methods for image and object retrieval exploit both appearance (via visual words) and local geometry (spatial extent, relative pose). In large scale problems, memory becomes a limiting factor - local geometry is stored for each feature detected in each image and requires storage larger than the inverted file and term frequency and inverted document frequency weights together. We propose a novel method for learning discretized local geometry representation based on minimization of average reprojection error in the space of ellipses. The representation requires only 24 bits per feature without drop in performance. Additionally, we show that if the gravity vector assumption is used consistently from the feature description to spatial verification, it improves retrieval performance and decreases the memory footprint. The proposed method outperforms state of the art retrieval algorithms in a standard image retrieval benchmark.
Available in digital repository of ČVUT.
Efficient Representation of Local Geometry for Large Scale Object Retrieval
State of the art methods for image and object retrieval exploit both appearance (via visual words) and local geometry (spatial extent, relative pose). In large scale problems, memory becomes a ...
Design of Experiments of AlN Reactive Sputtering
Mach, Pavel; Kolářová, Jana
2009 -
Reactive sputtering has been used for fabrication of AlN films. The process has been investigated in two levels of power of a generator, in two levels of the working pressure and in two levels of the working gas flow. The AlN films have been fabricated on a bottom Al electrodes and after sputtering of the AlN film a top Al electrode has been evaporated across the bottom one. This way capacitors have been formed. The capacitance and the loss factor of these capacitors have been measured. The process of fabrication of AlN films has been mathematically described using DOE.
Available in digital repository of ČVUT.
Design of Experiments of AlN Reactive Sputtering
Reactive sputtering has been used for fabrication of AlN films. The process has been investigated in two levels of power of a generator, in two levels of the working pressure and in two levels of the ...
Preparation of Electrically Conductive Adhesives Modified with AgNO3
2009 -
The goal of the work has been to find if addition of Ag+ ions into electrically conductive adhesive can improve its electrical conductivity. Ag+ ions can aggregate and form additional conductive bridges between filler particles and decrease electrical resistivity of adhesive this way. Ag+ ions have been formed by dissociation of AgNO3. Adhesives formed of bisphenol epoxy resin and silver flakes (one component and two components types) have been used for experiments. Two ways have been used for modification of adhesives with AgNO3: nitrate has been added in adhesive and dissociated during curing and annealing of adhesive, or nitrate has been dissociated in ethanol at first and this solution has been mixed up into adhesive. It has been found an improvement of electrical conductivity of two components adhesive after this modification.
Available in digital repository of ČVUT.
Preparation of Electrically Conductive Adhesives Modified with AgNO3
The goal of the work has been to find if addition of Ag+ ions into electrically conductive adhesive can improve its electrical conductivity. Ag+ ions can aggregate and form additional conductive ...
Influence of Carbon Nanotubes Added to a Commercial Adhesive
Bušek, David; Mach, Pavel
2009 -
This paper describes the influence of carbon nanotubes onto electrical properties of electrically conductive adhesives. This work is related to our previous research that described electrical connection network within electrically conductive adhesive and possible advantages of non-spherical particles distributed within the adhesive matrix. Two different commercial conductive adhesives were used in this experiment and different amounts of carbon nanotubes were mixed using different methods (ultrasound/rotation/spatula mixing) into the matrix. The positive effect in terms of mechanical properties can be expected according to previous research in the material field. The goal of this work is to describe the influence of this additional filler onto electrical parameters and generally to improve the adhesive properties.
Available in digital repository of ČVUT.
Influence of Carbon Nanotubes Added to a Commercial Adhesive
This paper describes the influence of carbon nanotubes onto electrical properties of electrically conductive adhesives. This work is related to our previous research that described electrical ...
The Ontology based FMEA of Lead Free Soldering Process
Molhanec, Martin; Mach, Pavel
2009 -
Paper is directed to improvement of a FMEA (Failure Mode and Effects Analysis) procedure in the area of reflow lead free soldering by the use of an ontology paradigm. Some ontology editor tools suitable for our intention are presented. Particular phases of ontology utilization for development of more exact approach to the FMEA procedure of reflow lead free soldering are analyzed. The goal of our work, a proposal of a user's guide for the FMEA procedure based on an ontology paradigm is presented. This user's guide is included in our university courses Management of Production Quality and Complex Quality Control provided by the Department of Electro-Technology of our faculty.
Available in digital repository of ČVUT.
The Ontology based FMEA of Lead Free Soldering Process
Paper is directed to improvement of a FMEA (Failure Mode and Effects Analysis) procedure in the area of reflow lead free soldering by the use of an ontology paradigm. Some ontology editor tools ...
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