Dr. Hristo S. Nikolov Profile

Dr. Hristo S. Nikolov

Assoc. prof. at Space Research and Technology Institute - BAS

SPIE Involvement:

Author

Publications (29)

Proceedings Article | 19 November 2024 Presentation + Paper

Improving the quality of information received from synthetic aperture radars implementing innovative passive reflectors

Hristo Nikolov, Mila Atanasova-Zlatareva, Konstantin Metodiev

Proceedings Volume 13195, 131950H (2024) https://doi.org/10.1117/12.3031980

KEYWORDS: Synthetic aperture radar, Reflectors, Design, Satellites, Interferometry, Geodesy, Remote sensing, Data processing

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In the last two decades the use of satellite remote sensing (RS) methods and technologies to study the ongoing processes on land surface and more specifically to obtain information about movements of the earth's surface due to geodynamic processes with different magnitudes (earthquakes, tectonic movements, landslides and collapse processes and etc.) has become ubiquitous due to more data available from operational synthetic aperture radars. The main driving force for this increase of the application of RS in studying the mentioned processes are the technological progress in the space industry, the creation of RS instruments for monitoring different objects from the Earth's surface with better spatial accuracy, improvement of the computational capabilities of modern computer systems as well as the increasingly and widespread development of innovative SAR data processing methods. One of the data sources for the thematic categories under the Copernicus program is the Sentinel-1 (S-1) satellite, which provides reliable SAR data regardless of atmospheric conditions. After their thematic processing by using the method of differential interferometry (DInSAR) and its improvements it is possible to obtain information about undelaying topography as well as the displacements that have occurred on the earth's surface. In order to increase the quality of this information for non-urbanized territories, it is necessary to deploy artificial, passive persistent reflectors (also known as corner reflectors - CRs) at well-known positions having verified backscattering characteristics. And since on the territory of Bulgaria, to the best knowledge of the authors, there are no available such passive reflectors as described above that are used to improve the reliability of the information obtained in SAR data processing from S-1 we designed, developed, and put into operation on a pilot basis a network of six reflectors. In this paper we present the setting-up process as well as first results after their deployment at selected site to study surface deformations caused by active fault structures.

Proceedings Article | 19 November 2024 Poster + Paper

Complex analysis of co-seismic deformations using SAR satellite data: application for the Balkan Peninsula

Mila Atanasova-Zlatareva, Hristo Nikolov

Proceedings Volume 13195, 131950N (2024) https://doi.org/10.1117/12.3031731

KEYWORDS: Earthquakes, Deformation, Synthetic aperture radar, Satellites, Interferometry, Satellite navigation systems, Interferometric synthetic aperture radar, Radar, Interferograms, Analytical research

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Proceedings Article | 13 September 2024 Open Access

Monitoring and inversion of three co-seismic events on the Balkan peninsula

Mila Atanasova, Hristo Nikolov, Lyuba Dimova, Reneta Raykova

Proceedings Volume 13212, 132120F (2024) https://doi.org/10.1117/12.3035471

KEYWORDS: Earthquakes, Deformation, Satellite navigation systems, Interferometry, Satellites, Interferometric synthetic aperture radar, Synthetic aperture radar, Interferograms, Modeling, Radar

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Proceedings Article | 21 September 2023 Paper

Framework concept of the project "The ancient wheat: growth and physiological characteristics under unfavorable stress factors and possibilities to alleviate the negative effects"

Denitsa Borisova, Hristo Nikolov, Ventzeslav Dimitrov, Anna Bouzekova-Penkova

Proceedings Volume 12786, 127860A (2023) https://doi.org/10.1117/12.2681932

KEYWORDS: Spectroscopy, Spectrometers, Remote sensing, Data acquisition, Agriculture, Tolerancing, Reflectivity, Aerospace engineering, Genetics

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The project “Тhe ancient wheat - growth and physiological characteristics under unfavorable stress factors and possibilities to alleviate the negative effects” is in line with the scientific priorities of the Bulgarian National Research Strategy: Improvement of the quality of life – food, environment protection, with the EU FP „Horizon Europe": Food, bioeconomy, agriculture & environment, and with launching an International Research Initiative for Wheat Improvement. This initiative is based on the urgent need for all countries to speed the progress in wheat in relation to its productivity, adaptivity, stress tolerance and efficient use of nutrients. In the same time the project match the objectives of the European Space Strategy and the European Space Policy - to support the appropriate research activities fostering the exploitation of the technical capabilities of the space community with the objective of seizing market opportunities and meeting the demands of the society. The project's goal is to use the technical capabilities for spectral measurements in remote sensing monitoring of wheat crops under unfavorable stress factors that is relevant to the European Policies in the domain of the most advances information technologies. Aiming optimal combination, integration and dissemination of data and services, the project will create further interdisciplinary perspectives. Spectral measurement data will enable the validation of information products with respect to the accuracy and reliability of the data. The planned spectral measurements and the acquired data closely correspond to the "Copernicus" program. The remotely sensing obtained data will be used for knowledge upgrading about relation between unfavorable stress factors and spectral data. This will contribute to the widespread dissemination of scientific results and will be used to link space remote monitoring and ground-truth data. This work is supported by the Bulgarian National Science Fund under Project KP-06-N56/15 (КП-06- Н56/15).

Proceedings Article | 26 October 2022 Presentation + Paper

Determination of surface deformations in the zone of nuclear power plant Kozloduy

Hristo Nikolov, Mila Atanasova-Zlatareva

Proceedings Volume 12267, 122670T (2022) https://doi.org/10.1117/12.2636265

KEYWORDS: Synthetic aperture radar, Interferometry, Coherence (optics), Buildings, Satellites, Geodesy, Data acquisition, Spatial resolution, Safety, Radar

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Proceedings Article | 26 October 2022 Poster + Presentation + Paper

Monitoring of coastal landslides using Sentinel-1 imagery

Mila Atanasova-Zlatareva, Hristo Nikolov, Anton Ivanov

Proceedings Volume 12267, 122670C (2022) https://doi.org/10.1117/12.2636221

KEYWORDS: Landslides, Satellite navigation systems, Synthetic aperture radar, Geodesy, Interferometry, Satellites, Radar, Interferometric synthetic aperture radar, Data processing, Remote sensing

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Proceedings Article | 12 September 2021 Presentation + Paper

Obtaining ground deformations by multitemporal DInSAR processing in vicinity of archaeological site “Solnitsata-Provadia”

Hristo Nikolov, Mila Atanasova

Proceedings Volume 11861, 118610C (2021) https://doi.org/10.1117/12.2599762

KEYWORDS: Synthetic aperture radar, Interferometry, Image processing, Signal processing, Satellites, Geodesy, Radar, Reliability, Data acquisition, Radar signal processing

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The Differential Radar Interferometry (DInSAR) technique provides fast and accurate means for detecting small displacements of the Earth’s surface having a magnitude in centimeters range. Applying this method monitoring of ground movements of natural or anthropogenic origin are reliably registered. The information is produced from the interferograms resulting from purposely processing the phase signal present in two SAR images from different dates over the one and the same area. The motivation behind this research was to study the crustal deformations that pose treat to the archaeological site “Solnitsa-Provadia” located in the area Mirovo salt deposit near the town Provadia, NE Bulgaria. It needs to be mentioned that the said monument is dated back to VI-V millennium BC and includes the remnants of an ancient city near Provadia. The registered deformations in the region are due to natural and anthropogenic factors. The mentioned factors have undisputable negative impact on the preservation of this historical site and justify the necessity of regular monitoring of the ongoing geodynamic processes. In this research the authors provide results based on multitemporal processing of freely accessible SAR data from Sentinel-1 mission by ESA. The information concerning the detected surface deformations was obtained by the DInSAR method. The multitemporal processing included creation of set of interferometric images from several periods with time span of four months. This interval was selected since it was needed to decrease the decorrelation of the phase signal caused by the vegetation and noise introduced by the atmosphere. In order to increase the reliability of the output information SAR data from ascending and descending orbits were processed which provided two different stereoscopic-like views to the investigated area. The results also have been compared with the trends of ground motions using data from repeated multi-year results geodetic measurements made at Mirovo geodynamic network.

Proceedings Article | 12 September 2021 Poster + Presentation + Paper

Surface displacements determinations at "Fish-Fish" landslide area based on UAV photogrammetric surveys and remotely sensed SAR data

Mila Atanasova, Hristo Nikolov

Proceedings Volume 11863, 1186317 (2021) https://doi.org/10.1117/12.2599416

KEYWORDS: Landslide (networking), Unmanned aerial vehicles, Synthetic aperture radar, Interferometry, Satellites, 3D modeling, Data acquisition, Signal processing, Image processing, Data modeling

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Proceedings Article | 20 September 2020 Presentation + Paper

Integrative use of GNSS and InSAR data: a case study of landslide on the Thracian rocks coastal slope

Mila Atanasova, Hristo Nikolov

Proceedings Volume 11534, 115340S (2020) https://doi.org/10.1117/12.2573641

KEYWORDS: Landslide (networking), Satellite navigation systems, Interferometric synthetic aperture radar, Synthetic aperture radar, Interferometry, Data archive systems, Geodesy, Stanford Linear Collider, Satellites, Reliability

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Proceedings Article | 20 September 2020 Presentation + Paper

Studying the slope deformations in a Bulgarian mountain by multitemporal DInSAR data processing

Hristo Nikolov, Mila Atanasova, Plamen Ivanov, Boyko Berov

Proceedings Volume 11533, 1153319 (2020) https://doi.org/10.1117/12.2573945

KEYWORDS: Data processing, Synthetic aperture radar, Satellites, Data acquisition, Roads, Bridges, Stochastic processes, Geodesy, Laser scanners, Analytical research

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Proceedings Article | 26 August 2020 Open Access

Spectral measurements over test site Novi Iskar for creating a specific data base

Denitsa Borisova, Valentina Hristova, Ventzeslav Dimitrov, Hristo Nikolov, Margarita Goranova

Proceedings Volume 11524, 115240E (2020) https://doi.org/10.1117/12.2570741

KEYWORDS: Databases, Spectroscopy, Remote sensing, Soil science, Satellites, Satellite imaging, Earth observing sensors, Reflectivity, Sensing systems, Aerospace engineering

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Proceedings Article | 26 August 2020 Paper

Evaluation of urban atlas and street tree layer 2012 local component datasets for Bulgaria

Ventzeslav Dimitrov, Nadezhda Ilieva, Hristo Nikolov

Proceedings Volume 11524, 1152417 (2020) https://doi.org/10.1117/12.2570763

KEYWORDS: Roads, Visualization, Accuracy assessment, Satellite imaging, Earth observing sensors, Satellites, Associative arrays, Geographic information systems, Vegetation, Agriculture

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Proceedings Article | 26 August 2020 Paper

Study of the contemporary state of the landslides in the northern Bulgarian Black Sea coast

Hristo Nikolov, Mila Atanasova, Keranka Vassileva, Rosen Nankin, Plamen Ivanov, Nikolay Dimitrov

Proceedings Volume 11524, 115241C (2020) https://doi.org/10.1117/12.2570678

KEYWORDS: Satellites, Satellite imaging, Raster graphics

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Proceedings Article | 26 August 2020 Paper

Studying seismic events via satellite interferometry

Hristo Nikolov, Valentina Protopopova, Mila Atanasova

Proceedings Volume 11524, 115241B (2020) https://doi.org/10.1117/12.2570676

KEYWORDS: Radar, Stanford Linear Collider, Coherence (optics)

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Proceedings Article | 4 October 2019 Presentation + Paper

Thematic spectral remote sensing data in land covers' monitoring over test region

Denitsa Borisova, Valentina Hristova, Ventzeslav Dimitrov, Hristo Nikolov, Margarita Goranova

Proceedings Volume 11156, 111560C (2019) https://doi.org/10.1117/12.2533119

KEYWORDS: Remote sensing, Databases, Aerospace engineering, Spectroscopy, Nomenclature, Sensing systems, Soil science, Vegetation, Spectrometers

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Proceedings Article | 3 October 2019 Paper

Studying the coastal landslides processes by InSAR

Mila Atanasova, Hristo Nikolov

Proceedings Volume 11156, 1115619 (2019) https://doi.org/10.1117/12.2532799

KEYWORDS: Landslides, Synthetic aperture radar, Geodesy, Interferometry, Satellites, Data processing, Interferometric synthetic aperture radar, Buildings, Image processing, Signal processing

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The landslides are one of the well-known natural hazards occurring on the North East Black Sea coast of Bulgaria. The previous researches that take into account the geological and meteorological peculiarities of this region confirmed that the geomorphological conditions in this region are extremely favorable for landslide formation. Two are the main drivers that are being responsible for activation of the landslide processes in the area investigated. The first one is the sea erosion and the other is the increasing groundwater level. The influence of those is highly aggravated by the construction activities that took place in the last decades and the lack of sewerage networks. Those findings are based on information provided by the national authority responsible for monitoring and filing the landslides in Bulgaria. This was the motivation for developing and implementing reliable and accurate method for operational monitoring of the landslide processes in the said area. For development of such method data from SAR instruments were used. In this specific study data from Sentinel-1 SAR mission were processed by the freely provided by ESA SNAP software. Final results are interferometric images (IFIs) providing information about the ground movements. In this paper we present results reflecting the subsidence in the area of a landslide located some 20km north of the Albena resort. In the last decade two events have caused damages to the infrastructure in the area - one occurred in January 2015 which was attributed to the heavy rains the previous summer and the other took place in mid of August 2018. Both have been studied by processing SAR data for the periods mentioned. The results obtained are considered reliable since they have been reaffirmed by geodetic surveys and other terrain measurements. The outcomes of this research will contribute to better understanding the ongoing slow movements of the Earth’s crust, and for forecasting and early warning of geological hazards.

Proceedings Article | 6 August 2018 Paper

Remote sensing measurements in creating thematic spectral library

Denitsa Borisova, Doyno Petkov, Roumen Nedkov, Hristo Nikolov, Ventzeslav Dimitrov, Margarita Metodieva Goranova, Daniela Avetisyan, Kameliya Radeva

Proceedings Volume 10773, 107730D (2018) https://doi.org/10.1117/12.2326005

KEYWORDS: Spectroscopy, Spectrometers, Remote sensing, Soil science, Minerals, Aerospace engineering, Reflectivity, Sensors

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Proceedings Article | 3 October 2017 Paper

Influence of different DEMs on the quality of the InSAR results: case study over Bankya and Mirovo areas

Hristo Nikolov, Mila Atanasova

Proceedings Volume 10426, 104260M (2017) https://doi.org/10.1117/12.2278393

KEYWORDS: Synthetic aperture radar, Interferometric synthetic aperture radar, Landslides, Data processing, Geodesy, Interferometry

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One of the key input parameters in obtaining end products from SAR data is the DEM used during their processing. This holds true especially when persistent scatterers InSAR method should be applied for example to study slow moving landslides or subsidence. Since nowadays most of the raw SAR data are of space borne origin for their correct processing to high precision products for relatively small areas with centimeter accuracy a DEM taking into account the particularities of the local topography is needed. Most of the DEMs used by the SAR processing software such as SRTM or ASTER are obtained by the same type of instrument and present some disagreements with height information acquired by leveling measurements or other geodetic means. This was the motivation for initiating this research – to prove the need of creating and using local DEM in SAR data processing at small scale and to check what the magnitude of the discrepancy between final InSAR products is in both cases where SRTM/ASTER and local DEM has been used. In addition investigated were two scenarios for SAR data processing – one with small baseline between image pairs and one having large baseline image pairs – in order to find out in which case local DEM has bigger impact. In course of this study two reference areas were considered – Bankya village near Sofia (SW region of Bulgaria) and Mirovo salt extraction site (NE region of Bulgaria). The reason those areas were selected lies in the high number of landslides registered and monitored by the competent authorities in the mentioned locations. The significance of the results obtained is witnessed by the fact that both sites we used have been included as reference sites for Bulgaria in the PanGeo EU funded project dealing with delivering information regarding ground instability geohazard as areas prone to subsidence of natural and manmade origin. In the said project largest part of the information has been extracted from Envisat SAR data, but now this information could be supplemented by adding such from Sentinel-1 derived by us. During this research two local DEMs have been extracted from the tiles including the areas of investigation, one using SRTM data and one from ASTER, and after this procedure both were compared to the DEM gathered by leveling measurements. Finally conclusions are drawn and a direction for future research steps is provided.

Proceedings Article | 23 October 2014 Paper

A framework for air quality monitoring based on free public data and open source tools

Hristo Nikolov, Denitsa Borisova

Proceedings Volume 9245, 92451P (2014) https://doi.org/10.1117/12.2067328

KEYWORDS: NOx, Data modeling, Atmospheric modeling, Gases, Satellites, Meteorology, Raster graphics, Carbon monoxide, Open source software, Geographic information systems

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In the recent years more and more widely accepted by the Space agencies (e.g. NASA, ESA) is the policy toward provision of Earth observation (EO) data and end products concerning air quality especially in large urban areas without cost to researchers and SMEs. Those EO data are complemented by increasing amount of in-situ data also provided at no cost either from national authorities or having crowdsourced origin. This accessibility together with the increased processing capabilities of the free and open source software is a prerequisite for creation of solid framework for air modeling in support of decision making at medium and large scale. Essential part of this framework is web-based GIS mapping tool responsible for dissemination of the output generated. In this research an attempt is made to establish a running framework based solely on openly accessible data on air quality and on set of freely available software tools for processing and modeling taking into account the present status quo in Bulgaria. Among the primary sources of data, especially for bigger urban areas, for different types of gases and dust particles, noted should be the National Institute of Meteorology and Hydrology of Bulgaria (NIMH) and National System for Environmental Monitoring managed by Bulgarian Executive Environmental Agency (ExEA). Both authorities provide data for concentration of several gases just to mention CO, CO₂, NO₂, SO₂, and fine suspended dust (PM10, PM2.5) on monthly (for some data on daily) basis. In the framework proposed these data will complement the data from satellite-based sensors such as OMI instrument aboard EOS-Aura satellite and from TROPOMI instrument payload for future ESA Sentinel-5P mission. Integral part of the framework is the modern map for the land use/land cover which is provided from EEA by initiative GIO Land CORINE. This map is also a product from EO data distributed at European level. First and above all, our effort is focused on provision to the wider public living in urbanized areas with one reliable source of information on the present conditions concerning the air quality. Also this information might be used as indicator for presence of acid rains in agriculture areas close to industrial or electricity plants. Its availability at regular basis makes such information valuable source in case of manmade industrial disasters or incidents such as forest fires. Key issue in developing this framework is to ensure the delivery of reliable data products related to air quality at larger scale that those available at the moment.

Proceedings Article | 24 October 2013 Paper

Ground-based multispectral measurements for airborne data verification in non-operating open pit mine “Kremikovtsi”

Denitsa Borisova, Hristo Nikolov, Doyno Petkov

Proceedings Volume 8893, 88930V (2013) https://doi.org/10.1117/12.2029151

KEYWORDS: Iron, Minerals, Mining, Reflectivity, Chemical analysis, Soil contamination, Soil science, Near infrared, Land mines, Aerospace engineering

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The impact of mining industry and metal production on the environment is presented all over the world. In our research we set focus on the impact of already non-operating ferrous “Kremikovtsi”open pit mine and related waste dumps and tailings which we consider to be the major factor responsible for pollution of one densely populated region in Bulgaria. The approach adopted is based on correct estimation of the distribution of the iron oxides inside open pit mines and the neighboring regions those considered in this case to be the key issue for the ecological state assessment of soils, vegetation and water. For this study the foremost source of data are those of airborne origin and those combined with ground-based in-situ and laboratory acquired data were used for verification of the environmental variables and thus in process of assessment of the present environmental status influenced by previous mining activities. The percentage of iron content was selected as main indicator for presence of metal pollution since it could be reliably identified by multispectral data used in this study and also because the iron compounds are widely spread in the most of the minerals, rocks and soils. In our research the number of samples from every source (air, field, lab) was taken in the way to be statistically sound and confident. In order to establish relationship between the degree of pollution of the soil and mulspectral data 40 soil samples were collected during a field campaign in the study area together with GPS measurements for two types of laboratory measurements: the first one, chemical and mineralogical analysis and the second one, non-destructive spectroscopy. In this work for environmental variables verification over large areas mulspectral satellite data from Landsat instruments TM/ETM+ and from ALI/OLI (Operational Land Imager) were used. Ground-based (laboratory and in-situ) spectrometric measurements were performed using the designed and constructed in Remote Sensing Systems Department at Space Research and Technology Institute thematically oriented spectrometric system TOMS working in the 0.4-0.9 μm range of the electromagnetic spectrum (EMS). For proper comparison between the data obtained from the different sources mentioned spectral transformations such as normalized difference and rationing data for two wavelengths were applied in order to avoid misinterpretation. Statistically significant dependence between the various spectral transformations and the quantitative content of the iron in the different type of compounds was established. The achieved results provided evidence that methodology used could be extended to other regions of the country polluted by the mining activities and should be also tested in the region of the copper and zinc extraction. In the next step of our research we intend to use the results obtained by the multitemporal analysis of the satellite and ground-based multispectral data for the same and the similar regions of interest.

Proceedings Article | 25 October 2012 Paper

Multitemporal satellite data in mine waste monitoring of Medet copper deposit

Denitsa Borisova, Hristo Nikolov, Doyno Petkov, Banush Banushev

Proceedings Volume 8538, 85380J (2012) https://doi.org/10.1117/12.974423

KEYWORDS: Mining, Copper, Satellites, Landsat, Environmental sensing, Remote sensing, Reflectivity, Land mines, Multispectral imaging, Earth observing sensors

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Proceedings Article | 19 October 2012 Paper

Remote sensing spectrometric system for emergency response on board of unmanned helicopter

Doyno Petkov, Hristo Nikolov, Denitsa Borisova

Proceedings Volume 8532, 85320A (2012) https://doi.org/10.1117/12.974593

KEYWORDS: Spectroscopy, Reflectivity, Vegetation, Unmanned aerial vehicles, Remote sensing, Visible radiation, Near infrared, Sensing systems, Agriculture, Computing systems

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Proceedings Article | 14 April 2012 Paper

Simultaneous vibration and high-speed microscopy to study mechanotransduction in living cells

David Holdsworth, Hristo Nikolov, Jen Au, Kim Beaucage, Jessica Kishimoto, S. Jeffrey Dixon

Proceedings Volume 8317, 831715 (2012) https://doi.org/10.1117/12.913312

KEYWORDS: Microscopy, Optical microscopy, Microscopes, Calcium, Prototyping, Tissues, Photometry, Bone, High speed imaging, Digital cameras

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Proceedings Article | 27 October 2011 Paper

Sub-pixel method for analysis of optical data in determining the overburden dumps and open pit mines

D. Borisova, H. Nikolov, D. Petkov, B. Banushev

Proceedings Volume 8181, 81811C (2011) https://doi.org/10.1117/12.898267

KEYWORDS: Mining, Reflectivity, Data modeling, Vegetation, Target detection, Near infrared, Spatial resolution, Landsat, Associative arrays, Earth observing sensors

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Mining plants are one of the factors having major negative impact on the area where they are situated. In our study this is the case of the mine production plant consisting of Elacite mine and Mirkovo floatation plant both located in central part of Stara Planina Mountain. In this study an attempt is made to delineate the overburden dumps and open pit mines by means of remotely sensed multispectral data with moderate spatial resolution (e.g. Landsat TM/ETM+ 30m) is a challenging task. The major difficulties arise from: 1) large period using the dump (introducing the need for multitemporal data); 2) the unknown proportions of vegetation, soil and embedding rock samples in the boundary areas and their seasonal variations; 3) relatively restricted access to places of interest. A variety of methods have been proposed to overcome the problems with pixels corresponding to two or more end-members, but a promising one is the soft classification which assign single pixel to several land cover classes in proportion to the area of the pixel that each class covers. In this scenario for every pixel of the data the correct proportion of the end-members should be found and then co-registered with the corresponding original pixel. As a result this sub-pixel classification procedure generates a number of fraction images equal to the number of land cover classes (end-members). The sub-pixel mapping algorithms we have exploited so far have one property in common: accuracy assessment of sub-pixel mapping algorithms is not easy because of missing high resolution ground truth data. One possible solution is to incorporate in the method adopted additional ex-situ and in-situ measured data from field and laboratory spectrometers with bandwidth about 1 nm. This study presents a successful implementation of soft classification method with additional, precise spectrometric data for determination of dump areas of the copper plant and open ore mine. The results achieved are proving that the in-situ gathered data provide coincidence of 93.5%. The main advantage of the presented technique is that mixed pixels are used during the training phase. Compared to these other techniques, the present one is simple, cheap and objective oriented. The results of this sub-pixel mapping implementation indicate that the technique can be useful to increase the resolution while keeping the classification accuracy high.

Proceedings Article | 17 March 2011 Paper

Image performance evaluation of a 3D surgical imaging platform

Ivailo Petrov, Hristo Nikolov, David Holdsworth, Maria Drangova

Proceedings Volume 7961, 79615O (2011) https://doi.org/10.1117/12.878804

KEYWORDS: Image analysis, 3D image processing, Modulation transfer functions, 3D acquisition, Magnesium, Image resolution, Stereoscopy, Surgery, 3D image reconstruction, Imaging systems

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Proceedings Article | 26 October 2010 Paper

Unmixing techniques for better segmentation of urban zones, roads, and open pit mines

Hristo Nikolov, Denitsa Borisova, Doyno Petkov

Proceedings Volume 7831, 78311L (2010) https://doi.org/10.1117/12.865027

KEYWORDS: Image segmentation, Roads, Reflectivity, Spectroscopy, Mining, Spatial resolution, Image processing, Multispectral imaging, Sensors, Earth observing sensors

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Proceedings Article | 7 October 2009 Paper

Fusion of Landsat TM and ground spectrometry data in monitoring of non-operating mine

Denitsa Borisova, Hristo Nikolov

Proceedings Volume 7478, 74781V (2009) https://doi.org/10.1117/12.830653

KEYWORDS: Mining, Reflectivity, Copper, Landsat, Vegetation, Data fusion, Spectroscopy, Data processing, Land mines, Earth observing sensors

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Proceedings Article | 12 April 2005 Paper

Virtual angiography for visualization and validation of computational fluid dynamics models of aneurysm hemodynamics

Matthew Ford, Gordan Stuhne, Hristo Nikolov, Stephen Lownie, David Holdsworth, David Steinman

Proceedings Volume 5744, (2005) https://doi.org/10.1117/12.594499

KEYWORDS: Angiography, 3D modeling, Hemodynamics, X-rays, Data modeling, Visualization, In vivo imaging, Visual process modeling, Blood circulation, Blood

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Proceedings Article | 28 April 2004 Paper

Doppler ultrasound in vitro modeling of turbulence in carotid vascular disease

Meghan Thorne, Tamie Poepping, Richard Rankin, Hristo Nikolov, David Holdsworth

Proceedings Volume 5373, (2004) https://doi.org/10.1117/12.535904

KEYWORDS: Turbulence, Doppler effect, In vitro testing, Arteries, Blood, Ultrasonography, Simulation of CCA and DLA aggregates, Independent component analysis, Data acquisition, Computer simulations

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