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segmentation of individual mangrove trees using UAV-based LiDAR data

ECOLOGICAL INFORMATICS 2023年 77卷

作者： You, Haotian Liu, Yao Lei, Peng Qin, Zhigang You, Qixu Guilin Univ Technol Coll Geomat & Geoinformat 12 Jiangan Rd Guilin 541006 Peoples R China Guilin Univ Technol Guangxi Key Lab Spatial Informat & Geomat 12 Jiangan Rd Guilin 541004 Peoples R China Guangxi Vocat Coll Water Resources & Elect Power Dept Hydraul Engn 99 Changgu Rd Nanning 530023 Peoples R China

Accurate assessment of structural parameters is essential to effectively monitor the mangrove resources. However, the extraction results of mangrove structural parameters are closely related to the segmentation results of individual trees. Although the results of individual tree segmentation are influenced by many factors, the specific factors affecting the segmentation results of individual mangrove trees, such as data source, image resolution, segmentation algorithm, and stand density, have not yet been elucidated. Therefore, in this study, canopy height models (CHMs) with different spatial resolutions were derived from unmanned aerial vehicle (UAV)-based light detection and ranging (LiDAR) data. Moreover, the watershed algorithm (WA), regional growth (RG), and improved K-nearest neighbour (KNN) and bird's eye view (BEV) faster region-based convolutional neural network (R-CNN) algorithms were used to segment the individual mangrove trees based on CHMs and LiDAR data at three sites with varying stand densities. Finally, different segmentation algorithms, image resolutions, and forest densities were comparatively assessed to determine their influence on the segmentation results of individual trees. segmentation accuracy of the improved KNN algorithm was the highest among the CHM-based algorithms, such as the WA, RG, and improved KNN algorithms, with an optimal F of 0.893 and minimum F of 0.628. R-CNN algorithm based on LiDAR data had an optimal F value of 0.931 and minimum F value of 0.612. Based on the segmentation results, the overall accuracy ranking of the different segmentation algorithms was BEV Faster R-CNN > improved KNN > RG > WA. The ranking of the segmentation results for sites with different stand densities was low-density (LD) > medium-density (MD) > high-density (HD). For LD and MD sites, the BEV Faster R-CNN algorithm had the highest F values (0.931 and 0.712, respectively). For the HD site, all algorithms performed poorly, and the F values of all alg

关键词： LiDAR data CHM segmentation algorithm Stand density Spatial resolution

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Elastic founder graphs improved and enhanced

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THEORETICAL COMPUTER SCIENCE 2024年 982卷

作者： Rizzo, Nicola Equi, Massimo Norri, Tuukka Maekinen, Veli Univ Helsinki Dept Comp Sci Helsinki Finland

Indexing labeled graphs for pattern matching is a central challenge of pangenomics. Equi et al. (2022) [14] developed the Elastic Founder Graph (EFG) representing an alignment of m sequences of length n, drawn from alphabet Sigma plus the special gap character: the paths spell the original sequences or their recombination. By enforcing the semi-repeat-free property, the EFG admits a polynomial-space index for linear-time pattern matching, breaking through the conditional lower bounds on indexing labeled graphs (Equi et al. [13]). In this work, we improve the space of the EFG index answering pattern matching queries in linear time, from linear in the length of all strings spelled by three consecutive node labels, to linear in the size of the edge labels. Then, we develop linear-time construction algorithms optimizing for different metrics: we improve the existing linearithmic construction algorithms to O(mn), by solving the novel exclusive ancestor set problem on trees;we propose, for the simplified gapless setting, an O(mn)-time solution minimizing the maximum block height, that we generalize by substituting block height with prefix-aware height. Finally, to show the versatility of the framework, we develop a BWT-based EFG index and study how to encode and perform document listing queries on a set of paths of the graphs, reporting which paths present a given pattern as a substring. We propose the EFG framework as an improved and enhanced version of the framework for the gapless setting, along with construction methods that are valid in any setting concerned with the segmentation of aligned sequences.

关键词： Multiple sequence alignment Pattern matching segmentation algorithm Suffix tree Document listing

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Sheep Posture Recognition Based on SVM 2nd

Sheep Posture Recognition Based on SVM

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2nd International Conference on Advanced Intelligent Technologies (ICAIT)

作者： Yao, YaJuan Tan, Han Yao, Juan Zhang, Cheng Tian, Fang Huazhong Agr Univ Coll Informat Wuhan Hubei Peoples R China Wuhan Vocat Coll Software & Engn Coll Mech Engn Wuhan Hubei Peoples R China

ISBN: (纸本)9789811697357;9789811697340

The evaluation of body size parameters and morphology based on body size parameters can reflect the growth and development characteristics, production performance and genetic characteristics of sheep. Therefore, studying the measurement of body size parameters and morphological evaluation is an effective way to determine the reasonable breeding of sheep farms and improve the breeding efficiency. In the measurement of human body size based on machine vision, the change of posture has a great influence on the human body size parameters. In this paper, a segmentation algorithm of sheep head, body and legs based on the sheep contour is proposed. Through this algorithm, five posture features are extracted, which are the angle between the hip point and the lower right corner coordinate of the head, the angle between the hip point and the lower left corner coordinate of the head, the angle between the lower right corner coordinate of the body and the lower right corner coordinate of the head, the angle between the lower right corner coordinate of the body and the upper left corner coordinate of the head and the length-width ratio of the circumscribed rectangle. The test results show that the accuracy of the program compiled by the hierarchical vector machine algorithm reaches 95.68%.

关键词： Hierarchical vector machine algorithm segmentation algorithm Sheep posture recognition

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A Laser Scanner Point Cloud Registration Method Using Difference of Normals (DoN) Based segmentation

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LASERS IN ENGINEERING 2022年第1-2期53卷 87-103页

作者： Lyu, J-H Wang, Z-W Zhou, Y. Meng, J. Wang, S-F Changchun Univ Sci & Technol Natl Demonstrat Ctr Expt Optoelect Engn Educ Sch Optoelect Engn 7089 Weixing Rd Changchun 130022 Jilin Peoples R China Changchun Univ Sci & Technol Key Lab Optoelect Measurement & Opt Informat Tran Minist Educ Sch Optoelect Engn 7089 Weixing Rd Changchun 130022 Jilin Peoples R China

The coarse registration is required before fine registration to obtain a better initial pose;however, it is difficult for coarse registration to obtain a better initial pose when the overlapping coefficient of source and target point cloud is low. To overcome this we propose a registration method using difference of normals (DoN) based segmentation algorithm and sample consensus initial alignment algorithm. First, the DoN based segmentation algorithm is employed to segment areas where obvious normal differences from source and target point cloud. Afterwards, Gaussian models for these subsets are established to find a pair of point cloud subsets with the most similar distribution. Then the sample consensus initial alignment algorithm (SAC-IA) is employed to register the matched subsets to obtain transformations between them, applied to source point cloud to find a better initial pose. Eventually, the iterative closest point (ICP) algorithm is involved to complete the registration. The experiments show the root mean square error (RMSE) of the registered point cloud using proposed method has been improved by 0.435 m compared with that of previous algorithm when the overlapping coefficient is 5%. The analysis shows the segmented region has clearer normal features;consequently, the SAC-IA algorithm to extract a more effective feature histogram to obtain a more accurate transformation.

关键词： Laser scanner point cloud registration iterative closest point (ICP) algorithm difference of normals (DoN) segmentation algorithm sample consensus initial alignment algorithm (SAC-IA)

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A segmentation procedure of the pervious area of the aorta artery from CT images without contrast medium

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MATHEMATICAL METHODS IN THE APPLIED SCIENCES 2020年第1期43卷 114-133页

作者： Costarelli, Danilo Seracini, Marco Vinti, Gianluca Univ Perugia Dept Math & Comp Sci 1 Via Vanvitelli I-06123 Perugia Italy

In this paper, we develop an algorithm for the segmentation of the pervious lumen of the aorta artery in computed tomography (CT) images without contrast medium, a challenging task due to the closeness gray levels of the different zones to segment. The novel approach of the proposed procedure mainly resides in enhancing the resolution of the image by the application of the algorithm deduced from the mathematical theory of sampling Kantorovich operators. After the application of suitable digital image processing techniques, the pervious zone of the artery can be distinguished from the occluded one. Numerical tests have been performed using 233 CT images, and suitable numerical errors have been computed and introduced ex novo to evaluate the performance of the proposed method. The above procedure is completely automatic in all its parts after the initial region of interest (ROI) selection. The main advantages of this approach relies in the potential possibility of performing diagnosis concerning vascular pathologies even for patients with severe kidney diseases or allergic problems, for which CT images with contrast medium cannot be achieved.

关键词： aorta artery biomedical image CT image equalization image processing mathematical procedure normalization sampling Kantorovich operator segmentation algorithm vascular apparatus

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Improving the reproducibility of MR-derived left ventricular volume and function measurements with a semi-automatic threshold-based segmentation algorithm

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INTERNATIONAL JOURNAL OF CARDIOVASCULAR IMAGING 2013年第3期29卷 617-623页

作者： Jaspers, Karolien Freling, Hendrik G. van Wijk, Kees Romijn, Elisabeth I. Greuter, Marcel J. W. Willems, Tineke P. Univ Groningen Univ Med Ctr Groningen Dept Radiol NL-9700 RB Groningen Netherlands Medis Med Imaging Syst BV NL-2300 AJ Leiden Netherlands Norwegian Univ Sci & Technol Dept Phys NO-7491 Trondheim Norway

To validate a novel semi-automatic segmentation algorithm for MR-derived volume and function measurements by comparing it with the standard method of manual contour tracing. The new algorithms excludes papillary muscles and trabeculae from the blood pool, while the manual approach includes these objects in the blood pool. An epicardial contour served as input for both methods. Multiphase 2D steady-state free precession short axis images were acquired in 12 subjects with normal heart function and in a dynamic anthropomorphic heart phantom on a 1.5T MR system. In the heart phantom, manually and semi-automatically measured cardiac parameters were compared to the true end-diastolic volume (EDV), end-systolic volume (ESV) and ejection fraction (EF). In the subjects, the semi-automatic method was compared to manual contouring in terms of difference in measured EDV, ESV, EF and myocardial volume (MV). For all measures, intra- and inter-observer agreement was determined. In the heart phantom, EDV and ESV were underestimated for both the semi-automatic. As the papillary muscles were excluded from the blood pool with the semi-automatic method, EDV and ESV were approximately 20 ml lower in the patients, whereas EF was approximately 16 % higher. Intra- and inter-observer agreement was overall improved with the semi-automatic method compared to the manual method. Correlation between manual and semi-automatic measurements was high (EDV: R = 0.99, ESV: R = 0.96;EF: R = 0.80, MV: R = 0.99). The semi-automatic method could exclude endoluminal muscular structures from the blood volume with significantly improved intra- and inter-observer variabilities in cardiac function measurements compared to the conventional, manual method, which includes endoluminal structures in the blood volume.

关键词： Cardiovascular magnetic resonance imaging Left ventricle Function Trabeculae segmentation algorithm

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Non-intrusive power load decomposition based on transient steady-state characteristics 8

Non-intrusive power load decomposition based on transient st...

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8th International Forum on Electrical Engineering and Automation (IFEEA)

作者： Li, Sai Guo, Xiaoxue Shao, Wenquan Wang, Junze Xian Polytech Univ Xian Peoples R China

ISBN: (纸本)9781665400886

For the traditional integer planning algorithms are limited to a single electrical feature quantity, resulting in poor identification of loads with similar electrical characteristics. Transient power and steady-state power are selected as load characteristics in this paper. On this basis, an improved integer programming algorithm based on low-frequency sampling is proposed. The method models the correlation between total power and various types of load power, and decomposes the total power sequence into several sub-power sequences by using the optimized segmentation algorithm. Meanwhile, the segmentation results are applied to the integer programming algorithm to improve its decomposition effect. Finally, the state switching time of each electricity load is identified on experimental data.

关键词： load decomposition non-intrusive integer programming segmentation algorithm

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A mean shift segmentation scheme using several pixel characteristics

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COMPUTERS & ELECTRICAL ENGINEERING 2021年 90卷 107022-107022页

作者： Cuevas, Erik Galvez, Jorge Avalos, Omar Chavarin, Angel Univ Guadalajara Dept Elect CUCEI Av Revolucion 1500 Guadalajara 44430 Jalisco Mexico

In this paper, a new segmentation method based on the mean shift (MS) algorithm is presented. The proposed approach divides the image into two sets of pixels: operative elements and inactive elements. In its first phase, the MS scheme considers only the operative elements. In its second stage, the results obtained by the MS method with the operative data are used to include the inactive data. During this stage, each inactive pixel is assigned to the cluster corresponding to the nearest operative pixel. As a final operation, clusters that maintain the minimal number of elements are blended with other nearby clusters. Our method has been tested against other current segmentation methods using test images extracted from the Berkley dataset. Numerical experiments demonstrate that our approach exhibits better performance in terms of consistency, quality, velocity and accuracy.

关键词： segmentation algorithm Mean shift method Non-local mean Kernel density estimator (KDE) Clustering methods

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A Novel Fusion Approach to Detect Brain Tumor Using Machine Learning for MRI Images

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TRAITEMENT DU SIGNAL 2022年第4期39卷 1363-1370页

作者： Kaliannan, Srisabarimani Rengaraj, Arthi Daniel, Alex Prabhu SRM Inst Sci & Technol ECE Ramapuram Chennai 600089 Tamil Nadu India Chettinad Hosp & Res Inst Chennai 603103 Tamil Nadu India

Medical Imaging challenges the recent researchers with variability of potential structures, positions and appearance strengths of various tumors present among the patients. The proposed work presents an effective brain tumor watershed segmentation technique created on 2D image followed by statistical feature extraction. Machine Learning models such as SVM, KNN, and XG boost were used to inspire the network design in order to extract tumor existence. The proposed segmentation algorithm has been tested and evaluated on original images that consist of an aggregate of 52 normal MRI volumes of distinctive patients with the presence of tumors or not signifying distinctive structures that obtains outcomes near to physical segmentation implementations. The novelty present in the proposed work classifies whether the tumor is present or not with an accuracy of approximately 98%.

关键词： brain tumor segmentation algorithm XG boost algorithm machine learning

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Thermoplastic 3D printing technology using a single filament for producing realistic patient-derived breast models

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PHYSICS IN MEDICINE AND BIOLOGY 2022年第4期67卷 045008-045008页

作者： Dukov, Nikolay Bliznakova, Kristina Okkalidis, Nikiforos Teneva, Tsvetelina Encheva, Elitsa Bliznakov, Zhivko Med Univ Varna Dept Med Equipment Elect & Informat Technol Healt Varna Bulgaria Morphe Thessaloniki Greece Med Univ Varna Dept Imaging Diagnost Intervent Radiol & Radiothe Varna Bulgaria

Objective. This work describes an approach for producing physical anthropomorphic breast phantoms from clinical patient data using three-dimensional (3D) fused-deposition modelling (FDM) printing. Approach. The source of the anthropomorphic model was a clinical Magnetic Resonance Imaging (MRI) patient image set, which was segmented slice by slice into adipose and glandular tissues, skin and tumour formations;thus obtaining a four component computational breast model. The segmented tissues were mapped to specific Hounsfield Units (HU) values, which were derived from clinical breast Computed Tomography (CT) data. The obtained computational model was used as a template for producing a physical anthropomorphic breast phantom using 3D printing. FDM technology with only one polylactic acid filament was used. The physical breast phantom was scanned at Siemens SOMATOM Definition CT. Quantitative and qualitative evaluation were carried out to assess the clinical realism of CT slices of the physical breast phantom. Main results. The comparison between selected slices from the computational breast phantom and CT slices of the physical breast phantom shows similar visual x-ray appearance of the four breast tissue structures: adipose, glandular, tumour and skin. The results from the task-based evaluation, which involved three radiologists, showed a high degree of realistic clinical radiological appearance of the modelled breast components. Measured HU values of the printed structures are within the range of HU values used in the computational phantom. Moreover, measured physical parameters of the breast phantom, such as weight and linear dimensions, agreed very well with the corresponding ones of the computational breast model. Significance. The presented approach, based on a single FDM material, was found suitable for manufacturing of a physical breast phantom, which mimics well the 3D spatial distribution of the different breast tissues and their x-ray absorption properties. A

关键词： physical breast phantoms 3D printing fused-deposition modelling PLA filament MRI breast CT breast segmentation algorithm

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