Computerized Analysis of Magnetic Resonance Images to Study Cerebral Anatomy in Developing Neonates

The study of cerebral anatomy in developing neonates is of great importance for the understanding of brain development during the early period of life. This dissertation therefore focuses on three challenges in the modelling of cerebral anatomy in neonates during brain development. The methods that have been developed all use Magnetic Resonance Images (MRI) as source data. To facilitate study of vascular development in the neonatal period, a set of image analysis algorithms are developed to automatically extract and model cerebral vessel trees. The whole process consists of cerebral vessel tracking from automatically placed seed points, vessel tree generation, and vasculature registration and matching. These algorithms have been tested on clinical Time-of- Flight (TOF) MR angiographic datasets. To facilitate study of the neonatal cortex a complete cerebral cortex segmentation and reconstruction pipeline has been developed. Segmentation of the neonatal cortex is not effectively done by existing algorithms designed for the adult brain because the contrast between grey and white matter is reversed. This causes pixels containing tissue mixtures to be incorrectly labelled by conventional methods. The neonatal cortical segmentation method that has been developed is based on a novel expectation-maximization (EM) method with explicit correction for mislabelled partial volume voxels. Based on the resulting cortical segmentation, an implicit surface evolution technique is adopted for the reconstruction of the cortex in neonates. The performance of the method is investigated by performing a detailed landmark study. To facilitate study of cortical development, a cortical surface registration algorithm for aligning the cortical surface is developed. The method first inflates extracted cortical surfaces and then performs a non-rigid surface registration using free-form deformations (FFDs) to remove residual alignment. Validation experiments using data labelled by an expert observer demonstrate that the method can capture local changes and follow the growth of specific sulcus

Medical imaging analysis with artificial neural networks

Given that neural networks have been widely reported in the research community of medical imaging, we provide a focused literature survey on recent neural network developments in computer-aided diagnosis, medical image segmentation and edge detection towards visual content analysis, and medical image registration for its pre-processing and post-processing, with the aims of increasing awareness of how neural networks can be applied to these areas and to provide a foundation for further research and practical development. Representative techniques and algorithms are explained in detail to provide inspiring examples illustrating: (i) how a known neural network with fixed structure and training procedure could be applied to resolve a medical imaging problem; (ii) how medical images could be analysed, processed, and characterised by neural networks; and (iii) how neural networks could be expanded further to resolve problems relevant to medical imaging. In the concluding section, a highlight of comparisons among many neural network applications is included to provide a global view on computational intelligence with neural networks in medical imaging

Sensor development for estimation of biomass yield applied to Miscanthus Giganteus

Precision Agriculture technologies such as yield monitoring have been available for traditional field crops for decades. However, there are currently none available for energy crops such as Miscanthus Giganteus (MxG), switch grass, and sugar cane. The availability of yield monitors would allow better organization and scheduling of harvesting operations. In addition, the real-time yield data would allow adaptive speed control of a harvester to optimize performance. A yield monitor estimates a total amount of biomass per coverage area in kg/m2 as a function of location. However, for herbaceous type crops such as MxG and switchgrass, directly measuring the biomass entering a harvester in the field is complicated and impractical. Therefore, a novel yield monitoring system was proposed. The approach taken was to employ an indirect measure by determining a volume of biomass entering the harvester as a function of time. The volume can be obtained by multiplying the diameter related cross-sectional area, the height and the crop density of MxG. Subsequently, this volume is multiplied by an assumed constant, material density of the crop, which results in a mass flow per unit of time. To determine the coverage area, typically the width of the cutting device is multiplied by the machine speed to give the coverage area per unit of time. The ratio between the mass flow and coverage area is now the yield per area, and adding GPS geo-references the yield. To measure the height of MxG stems, a light detection and ranging (LIDAR) sensor based height measurement approach was developed. The LIDAR was applied to scan to the MxG vertically. Two measurement modes: static and dynamic, were designed and tested. A geometrical MxG height measurement model was developed and analyzed to obtain the resolution of the height measurement. An inclination correction method was proposed to correct errors caused by the uneven ground surface. The relationship between yield and stem height was discussed and analyzed, resulting in a linear relationship. To estimate the MxG stem diameter, two types of sensors were developed and evaluated. Firstly, a LIDAR based diameter sensor was designed and tested. The LIDAR was applied to scan MxG stems horizontally. A measurement geometry model of the LIDAR was developed to determine the region of interest. An angle continuity based pre-grouping algorithm was applied to group the raw data from the LIDAR. Based on the analysis of the presentation of MxG stems in the LIDAR data, a fuzzy clustering technique was developed to identify the MxG stems within the clusters. The diameter was estimated based on the clustering result. Four types of clustering techniques were compared. Based on their performances, the Gustafson - Kessel Clustering algorithm was selected. A drawback of the LIDAR based diameter sensor was that it could only be used for static diameter measurement. An alternative system based on a machine vision based diameter sensor, which supported the dynamic measurement, was applied. A binocular stereo vision based diameter sensor and a structured lighting-based monocular vision diameter estimation system were developed and evaluated in sequence. Both systems worked with structured lighting provided by a downward slanted laser sheet to provide detectable features in the images. An image segmentation based algorithm was developed to detect these features. These features were used to identify the MxG stems in both the binocular and monocular based systems. A horizontally covered length per pixel model was built and validated to extract the diameter information from images. The key difference between the binocular and monocular stereo vision systems was the approach to estimate the depth. For the binocular system, the depth information was obtained based on disparities of matched features in image pairs. The features were matched based on a pixel similarity in both one dimensional and two dimensional based image matching algorithm. In the monocular system, the depth was obtained by a geometry perspective model of the diameter sensor unit. The relationship between yield and stem diameter was discussed and analyzed. The result showed that the yield was more strongly dependent upon the stem height than diameter, and the relationship between yield and stem volume was linear. The crop density estimation was also based on the monocular stereo vision system. To predict the crop density, the geometry perspective model of the sensor unit was further analyzed to calculate the coverage area of the sensor. A Monte Carlo model based method was designed to predict the number of occluded MxG stems based on the number of visible MxG stems in images. The results indicated that the yield has a linear relationship with the number of stems with a zero intercept and the average individual mass as the coefficient. All sensors were evaluated in the field during the growing seasons of 2009, 2010 and 2011 using manually measured parameters (height, diameter and crop density) as references. The results showed that the LIDAR based height sensor achieved an accuracy of 92% (0.3m error) to 98.2% (0.06m error) in static height measurements and accuracy of 93.5% (0.22m error) to 98.5% (0.05m error) in dynamic height measurements. For the diameter measurements, the machine vision based sensors showed a more accurate result than the LIDAR based sensor. The binocular stereo vision based and monocular vision based diameter measurement achieved an accuracy of 93.1% and 93.5% for individual stem diameter estimation, and 99.8% and 99.9% for average stem diameter estimation, while the achieved accuracy of LIDAR based sensor for average stem diameter estimation was 92.5%. Among three stem diameter sensors, the monocular vision based sensor was recommended due to its higher accuracy and lower cost in both device and computation. The achieved accuracy of machine vision based crop density measurement was 92.2%

Feature Representation for Online Signature Verification

Biometrics systems have been used in a wide range of applications and have improved people authentication. Signature verification is one of the most common biometric methods with techniques that employ various specifications of a signature. Recently, deep learning has achieved great success in many fields, such as image, sounds and text processing. In this paper, deep learning method has been used for feature extraction and feature selection.Comment: 10 pages, 10 figures, Submitted to IEEE Transactions on Information Forensics and Securit

Feature-based hybrid inspection planning for complex mechanical parts

Globalization and emerging new powers in the manufacturing world are among many challenges, major manufacturing enterprises are facing. This resulted in increased alternatives to satisfy customers\u27 growing needs regarding products\u27 aesthetic and functional requirements. Complexity of part design and engineering specifications to satisfy such needs often require a better use of advanced and more accurate tools to achieve good quality. Inspection is a crucial manufacturing function that should be further improved to cope with such challenges. Intelligent planning for inspection of parts with complex geometric shapes and free form surfaces using contact or non-contact devices is still a major challenge. Research in segmentation and localization techniques should also enable inspection systems to utilize modern measurement technologies capable of collecting huge number of measured points. Advanced digitization tools can be classified as contact or non-contact sensors. The purpose of this thesis is to develop a hybrid inspection planning system that benefits from the advantages of both techniques. Moreover, the minimization of deviation of measured part from the original CAD model is not the only characteristic that should be considered when implementing the localization process in order to accept or reject the part; geometric tolerances must also be considered. A segmentation technique that deals directly with the individual points is a necessary step in the developed inspection system, where the output is the actual measured points, not a tessellated model as commonly implemented by current segmentation tools. The contribution of this work is three folds. First, a knowledge-based system was developed for selecting the most suitable sensor using an inspection-specific features taxonomy in form of a 3D Matrix where each cell includes the corresponding knowledge rules and generate inspection tasks. A Travel Salesperson Problem (TSP) has been applied for sequencing these hybrid inspection tasks. A novel region-based segmentation algorithm was developed which deals directly with the measured point cloud and generates sub-point clouds, each of which represents a feature to be inspected and includes the original measured points. Finally, a new tolerance-based localization algorithm was developed to verify the functional requirements and was applied and tested using form tolerance specifications. This research enhances the existing inspection planning systems for complex mechanical parts with a hybrid inspection planning model. The main benefits of the developed segmentation and tolerance-based localization algorithms are the improvement of inspection decisions in order not to reject good parts that would have otherwise been rejected due to misleading results from currently available localization techniques. The better and more accurate inspection decisions achieved will lead to less scrap, which, in turn, will reduce the product cost and improve the company potential in the market

Grounding spatial relations in natural language by fuzzy representation for human-robot interaction

Additional file 1. Fourier coefficient decomposition for the first guess of the Newton’s method