Search results for "Local feature"

showing 7 items of 7 documents

Stability and Finiteness Properties of Medial Axis and Skeleton

2004

The medial axis is a geometric object associated with any bounded open set in \Bbb R^n which has various applications in computer science. We study it from a mathematical point of view. We give some results about its geometrical structure when the open set is subanalytic and we prove that it is stable under C2-perturbations when the open set is bounded by a hypersurface with positive local feature size.

Numerical AnalysisPure mathematicsControl and OptimizationAlgebra and Number TheoryOpen setStructure (category theory)Skeleton (category theory)CombinatoricsHypersurfaceControl and Systems EngineeringMedial axisBounded functionPoint (geometry)Local feature sizeMathematicsJournal of Dynamical and Control Systems
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RootsGLOH2: embedding RootSIFT 'square rooting' in sGLOH2

2020

This study introduces an extension of the shifting gradient local orientation histogram doubled (sGLOH2) local image descriptor inspired by RootSIFT ‘square rooting’ as a way to indirectly alter the matching distance used to compare the descriptor vectors. The extended descriptor, named RootsGLOH2, achieved the best results in terms of matching accuracy and robustness among the latest state-of-the-art non-deep descriptors in recent evaluation contests dealing with both planar and non-planar scenes. RootsGLOH2 also achieves a matching accuracy very close to that obtained by the best deep descriptors to date. Beside confirming that ‘square rooting’ has beneficial effects on sGLOH2 as it happe…

FEATURE EXTRACTIONLOCAL FEATUREComputer scienceFeature extractionComputingMethodologies_IMAGEPROCESSINGANDCOMPUTERVISIONScale-invariant feature transformFEATURE MATCHING02 engineering and technologyRobustness (computer science)Euclidean geometryComputer Science::Multimedia0202 electrical engineering electronic engineering information engineeringBeneficial effectsSettore ING-INF/05 - Sistemi Di Elaborazione Delle InformazioniSettore INF/01 - Informaticabusiness.industryImage matching020206 networking & telecommunicationsPattern recognitionCOMPUTER VISIONImage Matching Local Image Descriptors RootSIFT sGLOH2Computer Science::Computer Vision and Pattern RecognitionEmbedding020201 artificial intelligence & image processingComputer Vision and Pattern RecognitionArtificial intelligencebusinessSoftwareSquare rootingIMAGE MATCHING
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Keypoint descriptor matching with context-based orientation estimation

2014

Abstract This paper presents a matching strategy to improve the discriminative power of histogram-based keypoint descriptors by constraining the range of allowable dominant orientations according to the context of the scene under observation. This can be done when the descriptor uses a circular grid and quantized orientation steps, by computing or providing a global reference orientation based on the feature matches. The proposed matching strategy is compared with the standard approaches used with the SIFT and GLOH descriptors and the recent rotation invariant MROGH and LIOP descriptors. A new evaluation protocol based on an approximated overlap error is presented to provide an effective an…

GLOHComputingMethodologies_IMAGEPROCESSINGANDCOMPUTERVISIONScale-invariant feature transformContext basedReference orientationImage descriptorLIOPDiscriminative modelMROGHHistogramKeypoint matchingSIFTComputer Science::MultimediaComputer visionInvariant (mathematics)MathematicsDominant orientationSettore INF/01 - Informaticabusiness.industryPattern recognitionGridLocal featureRotation invarianceComputer Science::Computer Vision and Pattern RecognitionSignal ProcessingImage descriptors; Local features; Dominant orientation; Rotation invariance; Keypoint matching; SIFT; LIOP; MROGHComputer Vision and Pattern RecognitionArtificial intelligencebusiness
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PHOTOGRAMMETRY NOW AND THEN - FROM HAND-CRAFTED TO DEEP-LEARNING TIE POINTS

2022

Abstract. Historical images provide a valuable source of information exploited by several kinds of applications, such as the monitoring of cities and territories, the reconstruction of destroyed buildings, and are increasingly being shared for cultural promotion projects through virtual reality or augmented reality applications. Finding reliable and accurate matches between historical and present images is a fundamental step for such tasks since they require to co-register the present 3D scene with the past one. Classical image matching solutions are sensitive to strong radiometric variations within the images, which are particularly relevant in these multi-temporal contexts due to differen…

Settore ING-INF/05 - Sistemi Di Elaborazione Delle InformazioniRANSACtie pointsSettore INF/01 - Informaticadeep learningimage matchingcultural heritageHistorical imageslocal features
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HarrisZ$^+$: Harris Corner Selection for Next-Gen Image Matching Pipelines

2022

Due to its role in many computer vision tasks, image matching has been subjected to an active investigation by researchers, which has lead to better and more discriminant feature descriptors and to more robust matching strategies, also thanks to the advent of the deep learning and the increased computational power of the modern hardware. Despite of these achievements, the keypoint extraction process at the base of the image matching pipeline has not seen equivalent progresses. This paper presents HarrisZ$^+$, an upgrade to the HarrisZ corner detector, optimized to synergically take advance of the recent improvements of the other steps of the image matching pipeline. HarrisZ$^+$ does not onl…

Settore ING-INF/05 - Sistemi Di Elaborazione Delle InformazioniFOS: Computer and information sciencesHarris detectorSettore INF/01 - InformaticaComputer Vision and Pattern Recognition (cs.CV)ComputingMethodologies_IMAGEPROCESSINGANDCOMPUTERVISIONComputer Science - Computer Vision and Pattern Recognitionlocal featurecorner detectorArtificial IntelligenceSignal Processingkeypoint detectorStructure-from-MotionComputer Vision and Pattern RecognitionHarrisZSoftware
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Local methods for complex spatio-temporal point processes

2022

spatial statisticsecond-order characteristicspatio temporal point processesummary statisticsSettore SECS-S/01 - Statisticalocal feature
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Local test of random labelling for functional marked point processes

2022

We introduce the local t-weighted marked nth-order inhomogeneous K-function, in a Functional Marked Point Processes framework. We employ the proposed summary statistics to run a local test of random labelling, useful to identify points, and consequently regions, where this assumption does not hold, i.e. the functional marks are spatially dependent.

K-functionrandom labellingenvelopesSettore SECS-S/01 - StatisticaSpatio-temporal point proceLocal feature
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