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1

Historical and projected land-use / land cover changes of the Welmel River Watershed, Genale Dawa Basin, Ethiopia

Ayalew Solomon E., Nigussie Tewodros A.

Journal of Water and Land Development

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2023

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no. 58

89--98

EN

Human activities on land have grown significantly changing the entire landscape, while most of the changes have occurred in the tropics. The change has become a serious environmental concern at the local, regional and global scales. The intensity, speed, and degree of land use / land cover (LULC) changes are nowadays quicker compared to the past because of the development of society. Moreover, the rapid increase in population resulted in disturbing a large number of landscapes on the Earth. The main objective of this study was to detect historical (1990-2020) and predicted (2020-2050) LULC changes in the Welmel River Watershed, which is located in the Genale-Dawa Basin, South Eastern Ethiopia. The dataset of 1990, 2005, and 2020 was generated from Landsat 5, Landsat 7 and Landsat 8 respectively to determine the historical LULC map. The result of this study revealed that agriculture/ settlement increased by 6.85 km2 ∙y-1, while forestland declined by 9.16 km2 ∙y-1 over the last 31 years between 1990 and 2020. In the coming 31 years (by 2050), if the existing trend of the LULC change continues, agriculture/settlement land is expected to increase from 290.64 km2 in 2020 to 492.51 km 2 in 2050 at the rate of 6.73 km2 ∙y-1, while forestland is expected to shrink from 690.48 km2 in 2020 to 427.01 km2 in 2050 by a rate of 8.78 km2 ∙y-1.

2

A study of vegetation cover dynamics using landsat images: case of the beni haroun watershed (Algeria)

Roukia Namous, Abdelaziz Louamri, Khallef Boubaker

Geomatics, Landmanagement and Landscape

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2023

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no. 4

315--328

EN

Conducting a diachronic study of vegetation cover helps to assess its transformations over a period of time, allowing for a comprehensive assessment of the factors influencing these transformations. The purpose of this research is to analyze the vegetation cover spatio-temporal changes within Beni Haroun watershed, located in the northeast region of Algeria. Based on remote sensing data, two satellite images for the years 2009 and 2020 from Landsat 7 ETM+ and Landsat 8 OLI/TIRS were downloaded. The Normalized Difference Vegetation Index was employed to remotely detect and monitor the changes of the vegetation cover. It was calculated for both chosen dates, and the results were classified into four classes (no vegetation, sparse vegetation, moderate vegetation, dense vegetation), each representing a different vegetation density. The obtained maps showed a regression of the vegetation cover. The NDVI values have decreased from 0.77 in 2009 to 0.58 in 2020. Spatial patterns in the classified NDVI maps illustrated reduced vegetation cover demonstrated by an expansion of the no vegetation class: 35,3479 ha in 2009 and 56,7916 ha in 2020. The final map of the change detection depicted a predominance of the negative change throughout Beni Haroun watershed, in consequence of various controlling factors, including climate and human interventions.

3

Dynamics of Land Use and Land Cover Change Using Geospatial Techniques – A Case Study of Baghdad, Iraq

Mezaal Mustafa Ridha, Mahmoud Ammar S., Jasim Mohammed A., Naje Ahmed Samir

Ecological Engineering & Environmental Technology

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2022

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Vol. 23, iss. 6

216--226

EN

Urban land-cover change is increasing dramatically in most emerging countries. In Iraq and in the capital city (Baghdad). Active socioeconomic progress and political stability have pushed the urban border into the countryside at the cost of natural ecosystems at ever- growing rates. Widely used classifier of Maximum Likelihood was used for classification of 2003 and 2021 Landsat images. This classifier achieved 83.20% and 99.58% overall accuracies for 2003 and 2021 scenes, respectively. This study found that the urban area decreases by 16.4% and the agriculture area decrease by 5.4% over the period. On the other hand, barren land has been expanded up to more than 7% as well as increasing in water land that should probably due to flooding (almost 15% more than 2003). To reduce the undesirable effects of land-cover changes over urban ecosystems in Baghdad and in the municipality in specific, it is suggested that Baghdad develops an urban development policy. The emphasis of policy must be the maintenance an acceptable balance among urban infrastructure development, ecological sustainability and agricultural production.

4

Forest cover change detection in relation to climate variability and LULC changes using GIS and RS techniques. A case of the Kafa zone, southwest Ethiopia

Lemma Dejene Beyene, Gebretsadik Kinde Teshome, Debela Seifu Kebede

Journal of Water and Land Development

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2021

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no. 51

152--162

EN

Ethiopia has lost sizable forest resources due to rapid population growth and subsequent increase in the demand for agricultural land and fuel woods. In this study, GIS and remote sensing techniques were used to detect forest cover changes in relation to climate variability in the Kafa zone, southwest Ethiopia. Landsat Thematic Mapper (TM) images of 1986 and 1990, Enhanced Thematic Mapper plus (ETM+) image of 2010 and Landsat-8 Operational Land Imager (OLI-8) image of 2018 were acquired at a resolution of 30 m to investigate spatial-temporal forest cover and land use changes. A supervised image classification was made using a maximum likelihood method in ERDAS imagine V9.2 to identify the various land use and land cover classes. Both spectral (normalised difference vegetation index – NDVI) and post classification change detection methods were used to determine the forest cover changes. To examine the extent and rate of forest cover changes, post classification comparisons were made using ArcGIS V 10.4.1. A net forest cover change of 1168.65 ha (12%) was detected during the study period from 1986 to 2018. The drop in the NDVI from 0.06–0.64 in 1986 to (–0.08)–0.12 in 2018 indicated a marked forest cover change in the study area. The correlation of NDVI values with climate data indicated the forest was not in a stable condition. The declining of the forest cover was most likely caused by climate variability in the study area.

5

Performance of Unsupervised Change Detection Method Based on PSO and K-means Clustering for SAR Images

Shehab Jinan N., Abdulkadhim Hussein A.

International Journal of Electronics and Telecommunications

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2021

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Vol. 67, No. 3

403--408

EN

This paper presents unsupervised change detection method to produce more accurate change map from imbalanced SAR images for the same land cover. This method is based on PSO algorithm for image segmentation to layers which classify by Gabor Wavelet filter and then K-means clustering to generate new change map. Tests are confirming the effectiveness and efficiency by comparison obtained results with the results of the other methods. Integration of PSO with Gabor filter and k-means will providing more and more accuracy to detect a least changing in objects and terrain of SAR image, as well as reduce the processing time.

6

Monitoring and forecasting spatio-temporal LULC for Akure rainforest habitat in Nigeria

Aliyu Yahaya A, Youngu Terwase T., Abubakar Aliyu Z., Bala Adamu, Jesulowo Christianah I.

Reports on Geodesy and Geoinformatics

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2020

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Vol. 110

29--38

EN

For several decades, Nigerian cities have been experiencing a decline in their biodiversity resulting from rapid land use land cover (LULC) changes. Anticipating short/long-term consequences, this study hypothesised the effects of LULC variables in Akure, a developing tropical rainforest city in south-west Nigeria. A differentiated trend of urban LULC was determined over a period covering 1999–2019. The study showed the net change for bare land, built-up area, cultivated land, forest cover and grassland over the two decades to be -292.68 km2, +325.79 km2, +88.65 km2, +8.62 km2 and -131.38 km2, respectively. With a projected population increase of about 46.85%, the study identified that the built-up land cover increased from 1.98% to 48.61%. The change detection analysis revealed an upsurge in built area class. The expansion indicated a significant inverse correlation with the bare land class (50.97% to 8.66%) and grassland class (36.33% to 17.94%) over the study period. The study observed that the land consumption rate (in hectares) steadily increased by 0.00505, 0.00362 and 0.0687, in the year 1999, 2009 and 2019, respectively. This rate of increase is higher than studies conducted in more populated cities. The Cellular Automata (CA) Markovian analysis predicted a 37.92% growth of the study area will be the built-up area in the next two decades (2039). The 20-year prediction for Akure built-up area is within range when compared to CA Markov prediction for other cities across the globe. The findings of this study will guide future planning for rational LULC

7

The comparison of usage of satellite SAR and optical data in the process of urban growth monitoring

Opido P., Leśniak A.

Geology, Geophysics and Environment

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2016

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Vol. 42, no. 1

107--108

EN

The aim of this project was to monitor the temporal growth of the urban areas, on the example of the Krakow city (Poland). In recent years more frequent use of satellite data in environmental monitoring can be observed. Definitely the optical data are the most popular type of it. This kind of data are commonly used in many applications like land cover change detection, biomass study and in the map preparation process. Despite their many advantages they are very sensitive on the weather conditions. Thus they cannot be gathered in cloudy or rainy day. This case doesn’t occur when the satellite SAR (Synthetic Aperture Radar) system are used. The ability of SAR and optical systems in monitoring the temporal growth of the urban areas were presented in the past (Al Rawashdeh & Saleh 2006, Opido & Leśniak 2015). In these projects SAR and optical satellite systems were compared. The study presented here was performed on fifty archival SAR and optical images acquired between years 1992 and 2010. The images were grouped into five two-year time intervals. Each interval contains data stack of eight SAR and 2 Landsat images. For each group the analysis of land cover was performed. Each optical image was classified into three following classes: water, urban and green areas. The study of the SAR data was based on the analysis of coherent scatterers (Porzycka-Strzelczyk & Strzelczyk 2015). The most commonly used methods of coherent scatterer’s identification were tested: dispersion of amplitude, Log-Cumulant (Nicolas et al. 2004), Signal-to-cluter ratio (Ulander et al. 2010) and coherency method (Touzi 1999). The growth of the urban area was calculated by studying changes in the numbers of coherent scatterers on the SAR images. For the Landsat images changes in the area of the urban class were analyzed. Furthermore, regions of most and least intensive urban growth were detected. The next step of the project is to compare the presented results with those provided by new ESA (European Space Agency) satellites. Sentinel-1 provides SAR images with a much better spatial resolution than ERS-1, ERS-2 and Envisat satellites. Sentinel-2 has better spatial resolution and more spectral bands than Landsat-8 (Masek 2015). This will allow to achieve more precise maps of coherent scatterers.

8

Możliwości opracowania fotogrametrycznego lotniczych zdjęć ukośnych

Ostrowski W.

Archiwum Fotogrametrii, Kartografii i Teledetekcji

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2016

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Vol. 28

65--78

PL

Lotnicze zdjęcia ukośne stają się coraz popularniejszym źródłem danych fotogrametrycznych, a liczba zamawiających je miast rośnie również w Polsce. Tego typu zobrazowania dostarczają znacznie więcej informacji niż typowe zdjęcia pionowe, ponadto wielu użytkowników postrzega je jako „bardziej naturalne”. Rosnące zainteresowanie takimi danymi widoczne jest również na poziomie urzędów centralnych odpowiedzialnych za tworzenie opracowań kartograficznych w wielu państwach europejskich. Zdjęcia ukośne przez lata postrzegane były jako dane uzupełniające do lotniczego skaningu laserowego (ALS), uzupełnianie to ograniczało się w wielu wypadkach jedynie do wykorzystania zdjęć jako źródła tekstur dla modeli 3D powstających z danych ALS. Innym popularnym obszarem zastosowań było tworzenie przeglądarek zdjęć ukośnych, które w połączniu z Numerycznym Modelem Terenu pozwały na uproszczony pomiary wysokości obiektów na pojedynczym zdjęciu. Sytuacja ta zmienia się w ostatnich latach, gdy wraz z rozwojem technologii fotogrametrycznych możliwa stała się dokładna orientacja zdjęć ukośnych z wykorzystaniem automatycznej aerotriangulacji, a algorytmy służące do gęstego dopasowania obrazów przystosowane zostały do pracy z takimi danymi. Niniejszy artykuł z zawiera przegląd opublikowanych w ostatnich latach wyników orientacji bloków zdjęć ukośnych, w szczególności porównano wyniki testów dotyczących metod orientacji zdjęć ukośnych przeprowadzonych przez EuroSDR i ISPRS z wynikami badań prowadzonymi na innych polach testowych. Przeprowadzone badania eksperymentalne skupione były na dwóch głównych aspektach, pierwszym była ocena dokładności odwzorowania geometrii fasad budynków z wykorzystaniem gęstego dopasowania obrazów w przypadku bloku zdjęć ukośnych, w którym ze względu na małe pokrycia fasada odfotografowana jest jedynie na pojedynczym modelu. Drugim z poruszonych tematów badań była próba wykorzystania zdjęć ukośnych do wykrywania zmian w obrębie fasad budynków co nie jest możliwe z wykorzystaniem innych danych pozyskiwanych z pułapu lotniczego.

EN

Oblique aerial images are becoming an increasingly popular source of photogrammetric data, and they are being acquired by more and more municipalities in Poland also. This type of imagery can provide much more information than typical vertical photographs, and many users actually see them as "more natural." The growing interest in such data is becoming apparent even at the level of national mapping agencies responsible for the development of cartographic materials in many European countries. For years, oblique photographs were perceived as supplementary data for aerial laser scanning (ALS). Often, their supplementary role was limited to providing a source of textures for 3D models developed from ALS data. They were also commonly applied in dedicated oblique images viewers, which in conjunction with a Digital Terrain Model enabled simplified height measurements of features on a single photograph. With the advancement of photogrammetric technologies in recent years, the situation has been changing, and it has become possible to accurately orientate oblique images using automatic aerotriangulation and to apply adapted dense image matching (DIM) algorithms to work with this kind of data. This paper overviews the results of orientation of blocks of oblique photographs that have been published in recent years, focusing in particular on benchmarking results obtained by EuroSDR and ISPRS for methods of orientating oblique images. The purpose of the performed experimental tests was to determine the capacity for mapping the geometry of building façades using dense image matching and for detecting changes in urban space using oblique photographs with respect to façades. The research was focused on two main issues, the first one concerning the assessment of accuracy and the second an attempt to apply oblique photographs to the detection of changes in building façades, which is not possible using any other aerial photogrammetric data.

9

Random projections and Hotelling’s T2 statistics for change detection in high-dimensional data streams

Skubalska-Rafajłowicz E.

International Journal of Applied Mathematics and Computer Science

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2013

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Vol. 23, no. 2

447--461

EN

The method of change (or anomaly) detection in high-dimensional discrete-time processes using a multivariate Hotelling chart is presented. We use normal random projections as a method of dimensionality reduction. We indicate diagnostic properties of the Hotelling control chart applied to data projected onto a random subspace of Rn. We examine the random projection method using artificial noisy image sequences as examples.

10

Detekcja zmian pokrycia terenu na zdjęciach satelitarnych Landsat - porównanie trzech metod

Niedzielko J., Lewiński S.

Teledetekcja Środowiska

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2012

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T. 47

87--98

EN

Environmental changes are amongst the most important research subjects in geography. The changes may be natural, but also may be caused by human activity. Land cover is a significant component of the changing environment. Monitoring of its changes involves usage of satellite techniques. Landsat mission provides comparable data since forty years, very useful in land cover studies. Utilization of satellite techniques in such researches is developing quickly. This paper is an example of methods that enable quick and quite accurate assessment of range and spatial distribution of land cover changes. Practical application of image difference, principal component analysis and supervised classification to detect land cover changes is presented. Methods are applied to study area containing different land cover classes. Accuracy of methods was tested and compared. Combining methods presented in earlier researches, five new methods were developed: image difference, image difference with classification, classification, principal component analysis, principal component analysis with classification. Methods were applied to three different input datasets: pairs of images with different level of preprocessing. First dataset was a pair of georeferenced Landsat Thematic Mapper images. The second dataset was the same pair of images, atmospherically corrected using dark object subtraction method. Normalization of one image to the other provided the third dataset. Accuracy assessment was executed. Results were obtained from confusion matrices. Overall accuracy of methods was high, from 77% to 91%. Supervised classification was the most accurate method. Combining fully automatic methods with supervised classification has increased overall accuracy of automatic change detection, however not significantly. Studies on combining change detection methods should be continued. Future studies should concentrate on the automation of change detection process.

11

Change Detection for SAR Imagery Using Connected Components Analysis

Gromek A., Jenerowicz M.

International Journal of Electronics and Telecommunications

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2012

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Vol. 58, No. 2

111-116

EN

Objective of the described analysis is to provide consistent change detection method based on image processing techniques applied to the Synthetic Aperture Radar (SAR) images acquired over the same geographical area, but at two different time instances. The approach adopted in our work requires incorporation of results with the additional information derived from analysis based on mathematical morphology (MM) techniques and visual interpretation of multitemporal VHR optical satellite images.

12

Zastosowanie transformacji IR-MAD w detekcji zmian na zdjęciach satelitarnych

Aleksandrowicz S., Lewiński S., Kotarba A.

Archiwum Fotogrametrii, Kartografii i Teledetekcji

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2012

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Vol. 23

11--17

PL

W drugiej połowie lat dziewięćdziesiątych została opublikowana metoda analizy MAD (Multivariate Alteration Detection) służąca do wykrywania różnic występujących w wielowymiarowych zbiorach danych. Opracowano ją specjalnie dla celów detekcji zmian na podstawie zdjęć wielospektralnych i hiperspektralnych zarejestrowanych w różnym czasie. W ramach programu SATChMo/Geoland2 w Centrum Badań Kosmicznych rozpoznano możliwości zastosowania transformacji IR-MAD do detekcji zmian podstawowych form pokrycia terenu na zdjęciach satelitarnych wysokiej rozdzielczości. Prezentowana praca została wykonana na podstawie pary zdjęć KOMPSAT-2 obrazującej tereny północnej Hiszpanii w roku 2008 i 2010. Zaproponowany algorytm postępowania analizuje wyniki transformacji IR-MAD oraz dodatkowo informacje o pokrywie roślinnej i teksturze. Transformacja IR-MAD wykonywana jest na podstawie czterech kanałów spektralnych B, G, R i IR o rozdzielczości 4m, zdjęcia z pierwszego i drugiego terminu. Informacje uszczegóławiające możliwość zmian pokrywy roślinnej są pozyskiwane na podstawie wskaźników NDVI, natomiast źródłem informacji o teksturze są przetworzone za pomocą filtrów Sigma kanały panchromatyczne o rozdzielczości 1 m. Przyjęto założenia rozpoznawania zmian w pokryciu terenu, które nie są wynikiem naturalnych cykli fenologicznych. Najpierw identyfikowane są miejsca występowania zmian, następnie istnieje możliwość uzyskania informacji o ich charakterze.

EN

In the second half of the 1990s, MAD (Multivariate Alteration Detection) method designed for detecting differences in multidimensional datasets was published. It was developed specifically for change detection performed on the basis of multispectral and hyperspectral images collected at different times. Within the framework of the European program SATChMo/Geoland2, the Space Research Centre of Polish Academy of Sciences has recognized the possibility of applying the IR-MAD transformation to detect changes of the main form of land cover on high resolution satellite images. Presented work was performed on the basis of a pair of KOMPSAT-2 images presenting area of Northern Spain in 2008 and 2010. The proposed algorithm analyses the results of the IR-MAD transformation and also additional information about vegetation cover and texture. Transformation of IR-MAD is performed on the basis of four spectral channels; B, G, R and IR with a resolution of 4 m, of the images from the first and second term. Additional information concerning a possibility of appearing changes in vegetation are derived on the basis of NDVI index and texture layer produced by Sigma filters of panchromatic channel of 1m resolution. An assumption was made for classified changes of land cover, which are independent of natural phenological cycles. First, places of changes are located and next information of their nature (direction of changes) is obtained.

13

XML documents change detection system based on boolean linear programming task

Globa L., Alieksieiev M., Molchanov I.

Metody Informatyki Stosowanej

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2011

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nr 2

25-35

EN

This paper describes the main ideas of XML change detection system which is based on developed linear programming algorithm for XML change detection. The linear programming algorithm for XML change detection is developed to compare the trees of old web page and modified web page to find the changes between them. The approach presented in this paper differs from the previously cited ones. The first main idea of proposed algorithm is in paying attention only to quantitative changes in the tracked documents, instead of searching the exact changes sequence that produces the new document. The second main idea is in comparison of two document versions as if they are different documents. Such approach doesn’t need the reference map between XML tags of two documet versions. The proposed technique represents the change detection problem as the Boolean linear programming task and proposes effective solution method.

14

SETHI: The Flying Lab

Bruyant J. P., Dreuillet P., Du Plessis O. R., Oriot H., Dubois-Fernandez P., Cantalloube H.

International Journal of Electronics and Telecommunications

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2011

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Vol. 57, No. 1

29-35

EN

This paper presents the new-generation test bench SETHI, developed by ONERA, the French Aerospace Lab. SETHI is a medium range platform dedicated to environmental, scientific and security applications. The first part of this paper describes the system architecture, the development state and the future capabilities. A set of recent significant results are presented: these results cover various applications, such as high spatial resolution imaging, change detection between two acquisitions, biomass measurement in the rain forest, bistatic imaging and innovative measurements, such as air-to-air imaging or circular imaging.

15

Image change detection as a supplement for adaptive cruise control with stop&go functionality

Komoda J., Dybała J.

Diagnostyka

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2010

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nr 4(56)

43-47

EN

The theme of the project was to develop algorithms for image sequence analysis, allowing for improved functionality of adaptive cruise control equipped with Stop & Go function. Using Doppler radar could cause that on the small distances the object that crosses the path of the vehicle may not be detected. This is particularly important because of the Stop & Go function that allows the host vehicle to stop when preceding vehicle stops, and start automatically when the preceding vehicle pulls away. In such a situation collision with an undetected object located between the vehicles can occur. The requirement was to propose such algorithms that will work in real time and ensure compatibility with the existing system architecture.

PL

Tematem projektu było opracowanie algorytmów analizy sekwencji obrazów pozwalających na polepszenie funkcjonalności tempomatu adaptacyjnego wyposażonego w funkcję stop&go. Wykorzystanie dalekosiężnego radaru Dopplera może spowodować, że na małych odległościach nie zostanie wykryty obiekt przecinający trasę pojazdu. Ma to szczególne znaczenie ze względu na funkcję stop&go, która pozwala na zatrzymanie pojazdu, gdy pojazd poprzedzający się zatrzyma, oraz automatyczne ruszenie, gdy pojazd poprzedzający odjedzie. W takiej sytuacji może dojść do kolizji z niewykrytym obiektem znajdującym się pomiędzy pojazdami. Wymaganiem było zaproponowanie takich algorytmów, które pozwolą na pracę w czasie rzeczywistym oraz zapewnią kompatybilność z dotychczas wykorzystywaną architekturą sprzętu.

16

Models for monitoring the detection of land use change through the classification of urban areas

AlHaddad B., Burns M. C., Cladera J. R.

Roczniki Geomatyki

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2009

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T. 7, z. 2

7-12

EN

Remote sensing in urban areas has been a challenge for quite some time, due to theircomplexity and fragmentation with the combination of man-made and natural features. High-resolution satellite images offer potential for feature extraction and spatial modelling of urbanareas. Land use classification of urban areas may become possible by exploiting currenthigh-resolution sensor data. This proposed approach incorporates spectral information frommulti-spectral Spot images in an hierarchical image segmentation based on semanticallymeaningful thresholds. Urban areas are divided into various structure densities dependingupon land occupation and pixel neighbours, each region relating an administrative area, alreadyconverted (each pixel), to Points Of Interest (POIs) to form a geographic database for ourstudy in the income sections. The first stage, based on the identification of groups of points,exploits the fact that POIs are geographically distributed in clusters. In highly urban regions,the spatial density of the POIs is high, while in sparsely populated areas the density of pointsis much lower. To identify these different regions, a spatial density-based clustering techniquewas adopted. Once the groups of points are identified, the calculation of the boundaries ofthe areas containing each group of points defines the new regions. The third stage is wherethe regions are classified. This research is intended to find a way to delineate areas of differentland use and identify the land use type in every delineated area. Delaunay triangulation isdeployed to create spatial associations and structural analysis toward the spatial clustering ofphysical features in image space, with the aim of identifying land use. Delaunay triangulationhas been widely used in spatial analysis and spatial modelling (Bundy, Furse, 1995). We useDelaunay triangulation for deriving spatial relations between image objects and for structuralanalysis; mathematical morphology is applied to find the solid core of a spatial unit in 2Dspace; a Kernel Density function used to calculate a magnitude per cluster area from thecentroid point features using a kernel function to fit a smoothly tapered surface to each point.The Voronoi algorithm is proposed for deriving explicit boundaries between spatially adjacentland-use units. To test the approach, we selected a site in a suburban area within Barcelona Municipality, Spain.

PL

Na przestrzeni ostatnich kilku dekad zaobserwować można występowanie niekontrolowanego, nieskoordynowanego i nieplanowanego rozwoju urbanizacyjnego, powodującego rozprzestrzenianie sięmiast w wielu częściach globu. Gwałtowność dynamiki urbanizacyjnej ma znaczący wpływ na układyprzestrzenne związane z rozwojem i ekspansją wielkomiejskich obszarów. Hiszpania, w której terenpodlega urbanizacji w o wiele wyższym stopniu, niż wynikałoby to ze wzrostu populacji, nie stanowiwyjątku. Znaczna część ekspansji obszarów (pod)miejskich odbywa się kosztem gospodarstw rolnych, lasów oraz innych obszarów otwartych i zazwyczaj jest wynikiem niskiego zaludnienia tychobszarów. Rozsądne planowanie użytkowania terenu oraz zachowanie otwartej przestrzeni są wHiszpanii ważnymi problemami, jednakże obecnie dostępne informacje na temat rozprzestrzenianiasię miast i zmian użytkowania ziemi są bardzo niewielkie. Niniejszy artykuł przybliża kwestie pomiaruzmian miejskich obszarów zabudowanych z perspektywy czysto morfologicznej, oparte na poprzednich eksperymentalnych analizach obrazów satelitarnych datowanych na lata 1986-2004, pokazujących, że podejście pikselowe jest skuteczne dla grupowania przestrzennego, celem kwantyfikacji ianalizy procesu "peri-urbanizacji", co było celem doświadczenia w Barcelonie na przestrzeni tegookresu. Równolegle sprawdzana jest przydatność podejścia estymacji gęstości jądra (KDE) celemokreślenia najwyższej gęstości na podstawie "obszarów hot spot" centroidów klastrów, by zilustrować wykrywanie zmian obszarów zabudowanych. Poprzez diagram Voronoi'a sprawdzono równieżukłady centroidów w celu zrozumienia zachowania układu obszarów zabudowanych, które zwyklejest szeroko klasyfikowane jako losowe, jednorodne lub zgrupowane, zarówno w ramach oficjalnychgranic miejskich Barcelony, jak i poza nimi. Niniejsze badanie podzielić można na podstawowe etapy:1. wyodrębnienie rozłącznych obiektów z klasyfikacji użytkowania terenu na podstawie triangulacji Delone'a,2. monitorowanie nielicznych zmian obszarów zabudowanych przy użyciu parametru wygładzającego oraz gęstości jądra, 3. wykrywanie zmian obszarów zabudowanych przy użyciu dynamicznej struktury danych Voronoi'a, ,4. obliczenie statystyki odległości najbliższego sąsiada oraz dokładności. Na koniec warto nadmienić, iż zaprezentowane podejście można wykorzystać do monitorowaniazmian różnego rodzaju klas użytkowania ziemi na podstawie klasyfikacyjnych zbiorów danych.

17

Tracing cluster transitions for different cluster types

Ntoutsi I., Spiliopoulou M., Theodoridis Y.

Control and Cybernetics

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2009

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Vol. 38, no 1

239-259

EN

Clustering algorithms detect groups of similar population members, like customers, news or genes. In many clustering applications the observed population evolves and changes over time, subject to internal and external factors. Detecting and understanding changes is important for decision support. In this work, we present the MONIC+ framework for cluster-type-specific transition modeling and detection. MONIC+ encompasses a typification of clusters and cluster-type-specific transition indicators, by exploiting cluster topology and cluster statistics for the transition detection process. Our experiments on both synthetic and real datasets demonstrate the usefulness and applicability of our framework.

18

Change Detection of Remote Sensing Images with Semi-supervised Multilayer Perceptron

Patra S., Ghosh S., Ghosh A.

Fundamenta Informaticae

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2008

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Vol. 84, nr 3-4

429-442

EN

A context-sensitive change-detection technique based on semi-supervised learning with multilayer perceptron is proposed here. In order to take contextual information into account, input patterns are generated considering each pixel of the difference image along with its neighboring pixels. A heuristic technique is suggested to identify a few initial labeled patterns without using ground truth information. The network is initially trained using these labeled data. The unlabeled patterns are iteratively processed by the already trained perceptron to obtain a soft class label. Experimental results, carried out on two multispectral and multitemporal remote sensing images, confirm the effectiveness of the proposed approach.

19

Presenting a technique for registering images and range data using a topological representation of a path within an environment

Ferreira F., Davim L., Rocha R., Dias J., Santos V.

Journal of Automation Mobile Robotics and Intelligent Systems

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2007

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Vol. 1, No. 3

47-56

EN

This article presents a novel method to the utilize topological representation of a path, thatpath that is created from sequences of images from digital cameras and sensor data from range sensors. A topological representation of the environment is created by leading the robot around the environment during a familiarisation phaseLeading the robot around the environment during a familiarisation phase creates a topological representation of the environment. While moving down the same path, the robot is able to localise itself within the topological representation that is has been previously created. The principal contribution to the state of the art is that, by using a topological representation of the environment, individual 3D data sets acquired from a set of range sensors need not be registered in a single, [Global] Coordinate Reference System. Instead, 3D point clouds for small sections of the environment are indexed to a sequence of multi-sensor views, of images and range data. Such a registration procedure can be useful in the construction of 3D representations of large environments and in the detection of changes that might occur within these environments.

20

Software and methods for steganography

Bailey K., Condeli J., Curran K.

Image Processing & Communications

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2005

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Vol. 10, no 2

103-130

EN

The object of steganography is to send a message through some innocuous carrier to a receiver while preventing anyone else from knowing that a message is being sent. The carrier can be one of several forms of digital media however the most common type of carrier used is an image. The image should not attract any attention as a carrier of a message and should look as close as possible to an ordinary image. This paper summarises recent research in the area of steganography with the aim of evaluating the trends in this area and developing a perspective on it. It looks at the application of steganography to digital images. Different ways of hiding the message sender arc discussed. An extensive study of existing steganography software is provided. Watermarking and cryptography are briefly described. Watermarking is the process of hiding information in a carrier in order to protect the ownership of text, music, films and art. Steganography techniques can be used for the purposes of watermarking. It is important also to briefly mention cryptography as it is commonly used along with steganography to generate an encrypted message to be hidden in a carrier.