Browsing by Subject "Morphological processing"
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Item Open Access A comparative study of five algorithms for processing ultrasonic arc maps(2005) Kurt, ArdaIn this work, one newly proposed and four existing algorithms for processing ultrasonic arc maps are compared for map-building purposes. These algorithms are the directional maximum, Bayesian update, morphological processing, voting and thresholding, and arc-transversal median algorithm. The newly proposed method (directional maximum) has a basic consideration of the general direction of the mapped surface. Through the processing of arc maps, each method aims at overcoming the intrinsic angular uncertainty of ultrasonic sensors in map building, as well as eliminating noise and cross-talk related misreadings. The algorithms are implemented in computer simulations with two distinct motion-planning schemes for ground coverage, wall following and Voronoi diagram tracing. As success criteria of the methods, mean absolute difference with the actual map/profile, fill ratio, and computational cost in terms of CPU time are utilized. The directional maximum method performed superior to the existing algorithms in mean absolute error, was satisfactory in fill ratio and performed second best in processing times. The results indicate various trade-offs in the choice of algorithms for arc-map processing.Item Open Access Comparison of two methods of surface profile extraction from multiple ultrasonic range measurements(Institute of Physics Publishing, 2000) Barshan, B.; Backent, D.Two novel methods for surface profile extraction based on multiple ultrasonic range measurements are described and compared. One of the methods employs morphological processing techniques, whereas the other employs a spatial voting scheme followed by simple thresholding. Morphological processing exploits neighbouring relationships between the pixels of the generated arc map. On the other hand, spatial voting relies on the number of votes accumulated in each pixel and ignores neighbouring relationships. Both approaches are extremely flexible and robust, in addition to being simple and straightforward. They can deal with arbitrary numbers and configurations of sensors as well as synthetic arrays. The methods have the intrinsic ability to suppress spurious readings, crosstalk and higher-order reflections, and process multiple reflections informatively. The performances of the two methods are compared on various examples involving both simulated and experimental data. The morphological processing method outperforms the spatial voting method in most cases with errors reduced by up to 80%. The effect of varying the measurement noise and surface roughness is also considered. Morphological processing is observed to be superior to spatial voting under these conditions as well.Item Open Access Impaired morphological processing: insights from multiple sclerosis(Routledge, 2023-06-13) Boudelaa, S.; Boujraf, S.; Belahcen, F.; Ben Zagmout, M; Farooqui, AusafMultiple Sclerosis (MS) is a neurological disease characterised by damage affecting large bundles of white matter fibres. Morphological segmentation of complex words (e.g. walked) into stems (walk) and suffixes (∼ed) is thought to depend on intact white matter. We tested the hypothesis that Arabic speaking patients with MS may lose the ability to segment morphologically complex words in a primed lexical decision task using word pairs that shared either a root and a semantic relationship (+R + S, e.g. “AnzAl”–“nuzwl” lowering-landing), a root without semantics (+R–S, e.g. “rtAbp”–“trtyb” monotony-tidying up),a semantic relationship (–R + S, e.g. “xyr”–“nEmp” good-grace), or a phonological relationship (–R + Phon, e.g. “mEdn”–“mEAnd” mineral-stubborn). While healthy controls showed priming by root regardless of semantics and inhibition by phonology, the patients showed facilitation by semantics (+R + S and –R + S), and inhibition by phonology (–R + Phon). These findings are used to adjudicate three contending models of lexical processing.Item Open Access Kentsel yapıların biçimbilimsel bölütlenmesi(IEEE, 2007-06) Akçay, H. Gökhan; Aksoy, SelimYüksek çözünürlükteki uzaktan algılamalı uydu görüntülerinde bölütleme kent uygulamalarında önemli bir problemdir çünkü elde edilen bölütlemelerle sınıflandırma için piksel tabanlı spektral bilginin yanında uzamsal ve yapısal bilgiler elde edilebilir. Bu bildiride, biçimbilimsel işlemlerle çıkarılan yapısal bilgi ve ana bileşenler analizi ile özetlenen spektral bilgi kullanılarak gürültüden etkilenmeyen bölütler elde eden bir yöntem sunduk. Yapılan deneyler yöntemin görüntü üzerinde komşuluk bilgisini ve spektral bilgiyi beraber kullanmayan başka bir yönteme göre daha düzgün ve anlamlı yapılar bulduğunu göstermiştir. Automatic segmentation of high-resolution remote sensing imagery is an important problem in urban applications because the resulting segmentations can provide valuable spatial and structural information that are complementary to pixel-based spectral information in classification. We present a method that combines structural information extracted by morphological processing with spectral information summarized using principal components analysis to produce precise segmentations that are also robust to noise. The experiments show that the method is able to detect structures in the image which are more precise and more meaningful than the structures detected by another approach that does not make strong use of neighborhood and spectral information.Item Open Access Morphological surface profile extraction with multiple range sensors(Elsevier, 2001) Barshan, B.; Başkent, D.A novel method is described for surface pro"le extraction based on morphological processing of multiple range sensor data. The approach taken is extremely #exible and robust, in addition to being simple and straightforward. It can deal with arbitrary numbers and con"gurations of sensors as well as synthetic arrays. The method has the intrinsic ability to suppress spurious readings, crosstalk, and higher-order re#ections, and process multiple re#ections informatively. The performance of the method is investigated by analyzing its dependence on surface structure and distance, sensor beamwidth, and noise on the time-of-#ight measurements. 2001 Pattern Recognition Society. Published by Elsevier Science Ltd. All rights reserved.Item Open Access Surface profile determination from multiple sonar data using morphological processing(Sage Publications Ltd., 1999-08) Başkent, D.; Barshan, B.This paper presents a novel method for surface profile determination using multiple sensors. Our approach is based on morphological processing techniques to fuse the range data from multiple sensor returns in a manner that directly reveals the target surface profile. The method has the intrinsic ability of suppressing spurious readings due to noise, crosstalk, and higher-order reflections, as well as processing multiple reflections informatively. The approach taken is extremely flexible and robust, in addition to being simple and straightforward. It can deal with arbitrary numbers and configurations of sensors as well as synthetic arrays. The algorithm is verified both by simulating and experiments in the laboratory by processing real sonar data obtained from a mobile robot. The results are compared to those obtained from a more accurate structured-light system, which is, however, more complex and expensive.