Intertidal bars are common features on meso-and macro-tidal sandy beaches with low to moderate wa... more Intertidal bars are common features on meso-and macro-tidal sandy beaches with low to moderate wave energy environments. Understanding their morphodynamics is, hence, crucial for enhancing our knowledge on beach processes which is beneficial for coastal management. However, most studies have been limited by assessing bar systems two-dimensionally and typically over the short-term. Morphology and dynamics of an intertidal bar system in a macro-tidal environment have been investigated using bi-annual LiDAR topographic surveys over a period of seven years and along 3.2 km at Groenendijk beach (Belgium). The detected bars demonstrate that a morphology of an intertidal bar is permanently on the beach. However, these individual features are dynamic and highly mobile over the course of half a year. The mean height and width of the bars were 1.1 and 82 m, respectively. The highest, steepest, and asymmetric features were found on the upper beach, while they were least developed in the lower ...
2007 International Workshop on the Analysis of Multi-temporal Remote Sensing Images, 2007
ABSTRACT Change detection based on satellite remote sensing relies on the comparison of multispec... more ABSTRACT Change detection based on satellite remote sensing relies on the comparison of multispectral reflectance acquired at different dates. A major problem in forest change detection is to separate the signal change related to forest conversion from other sources of noise such as the ever-changing state of a forest stand from the regrowth to the mature age. This research aims at characterizing spectral reflectance over the whole forest succession in order to quantify the reflectance dynamics and to identify the most appropriate spectral signal thanks to a robust object-based change detection approach. From a large sample of spruce stands, spectral trajectories of forest cycle were derived for green, red and NIR reflectances and the NDVI derived from SPOT-HRVIR images. These trajectories were found typical for spruce stands and consistent between satellite images. Based on the object-based change detection method using image differencing, the combination of all spectral bands was proved more efficient to detect changes and more discriminant to distinguish them than any single spectral band or NDVI. Two forest changes, namely the clearing and the regrowth, have been distinguished based on multivariate analysis for different temporal resolutions. Finally, tills study emphasized the need of a better characterization of changes of interest for defining appropriate forest monitoring systems.
... non-invasive determination of shallow subsurface hydrogeophysical properties at the field sca... more ... non-invasive determination of shallow subsurface hydrogeophysical properties at the field scale through the ... Therefore, quantifying the relative difference between the near-infrared reflectance 'peak' and the ... Logarithmic scale 10800 ohm.m. Data collected on the 4th April 2005 ...
ABSTRACT: Future Remote Sensing data will include hyperspectral data more and more. This study fr... more ABSTRACT: Future Remote Sensing data will include hyperspectral data more and more. This study frames in the preliminary studies to investigate the possibilities of these types of data. In this framework experimen-tal flights were organised by VITO (Flemish Institute for ...
ABSTRACT In this study it is shown how kriging with measurement errors (KME) is useful as opposed... more ABSTRACT In this study it is shown how kriging with measurement errors (KME) is useful as opposed to more conventional kriging methods. The goal of the study was to properly account for field measured soil electrical conductivity (EC) as soft data for the spatial prediction of soil salinity. Samplings were done in autumn 2009 (first dataset), spring and autumn 2010 (second and third datasets) around Uromieh Lake, northwest of Iran. The salinity was measured both in the field and laboratory for the first and second datasets. The first dataset was used for error measurements from which an error variance can be estimated. The measured errors were then used for characterizing probabilistic type soft data using the second dataset. The KME with only soft data (SKME), KME with both soft and hard data (HSKME) and ordinary kriging methods were compared. Validation criteria, mean error (ME) and mean squared error (MSE) were used for comparing the methods. Finally, the SKME method was applied as a way of improving the salinity prediction for the third dataset where only field measured soil salinity data were available. Comparing different kriging methods, Ordinary Kriging (OK) showed the best results among the comparing methods with ME and MSE equal to −0.12 and 0.55 respectively. SKME with ME equal to −0.13 was slightly different from OK and SKME with ME equal to −0.24 resulted in more bias predictions among others. KME method has shown to be useful for soil salinity monitoring and can effectively reduce sampling time.
Forest monitoring requires more automated systems to analyse the large amount of remote sensing d... more Forest monitoring requires more automated systems to analyse the large amount of remote sensing data. A new method of change detection is proposed for identifying forest land cover change using high spatial resolution satellite images. Combining the advantages of image segmentation, image differencing and stochastic analysis of the multispectral signal, this OB-Reflectance method is object-based and statistically driven. From a multidate image, a single segmentation using region-merging technique delineates multidate objects characterised by their reflectance differences statistics. Objects considered as outliers from multitemporal point of view are successfully discriminated thanks to a statistical procedure, i.e., the iterative trimming. Based on a chi-square test of hypothesis, abnormal values of reflectance differences statistics are identified and the corresponding objects are labelled as change. The object-based method performances were assessed using two sources of reference ...
We present an integrated modeling procedure for near-field ground-penetrating radar (GPR) and ele... more We present an integrated modeling procedure for near-field ground-penetrating radar (GPR) and electromagnetic induction (EMI) for the non-invasive determination of the constitutive properties of planar layered media in a high-resolution digital soil mapping framework. We validated the approach using GPR and EMI instruments set up using vector network analyzer technology, though the proposed methods also apply to conventional instruments. The antennas are modeled using a set of infinitesimal dipoles and characteristics, frequency-dependent, global reflection and transmission coefficients. The GPR and EMI antennas were calibrated using measurements at different heights over water. The electromagnetic models were then successfully validated using measurements acquired over water subject to different salinity levels. Finally, GPR and EMI data fusion strategies were investigated for resolving non-uniqueness issues that are inherent to multilayered media reconstruction
Intertidal bars are common features on meso-and macro-tidal sandy beaches with low to moderate wa... more Intertidal bars are common features on meso-and macro-tidal sandy beaches with low to moderate wave energy environments. Understanding their morphodynamics is, hence, crucial for enhancing our knowledge on beach processes which is beneficial for coastal management. However, most studies have been limited by assessing bar systems two-dimensionally and typically over the short-term. Morphology and dynamics of an intertidal bar system in a macro-tidal environment have been investigated using bi-annual LiDAR topographic surveys over a period of seven years and along 3.2 km at Groenendijk beach (Belgium). The detected bars demonstrate that a morphology of an intertidal bar is permanently on the beach. However, these individual features are dynamic and highly mobile over the course of half a year. The mean height and width of the bars were 1.1 and 82 m, respectively. The highest, steepest, and asymmetric features were found on the upper beach, while they were least developed in the lower ...
2007 International Workshop on the Analysis of Multi-temporal Remote Sensing Images, 2007
ABSTRACT Change detection based on satellite remote sensing relies on the comparison of multispec... more ABSTRACT Change detection based on satellite remote sensing relies on the comparison of multispectral reflectance acquired at different dates. A major problem in forest change detection is to separate the signal change related to forest conversion from other sources of noise such as the ever-changing state of a forest stand from the regrowth to the mature age. This research aims at characterizing spectral reflectance over the whole forest succession in order to quantify the reflectance dynamics and to identify the most appropriate spectral signal thanks to a robust object-based change detection approach. From a large sample of spruce stands, spectral trajectories of forest cycle were derived for green, red and NIR reflectances and the NDVI derived from SPOT-HRVIR images. These trajectories were found typical for spruce stands and consistent between satellite images. Based on the object-based change detection method using image differencing, the combination of all spectral bands was proved more efficient to detect changes and more discriminant to distinguish them than any single spectral band or NDVI. Two forest changes, namely the clearing and the regrowth, have been distinguished based on multivariate analysis for different temporal resolutions. Finally, tills study emphasized the need of a better characterization of changes of interest for defining appropriate forest monitoring systems.
... non-invasive determination of shallow subsurface hydrogeophysical properties at the field sca... more ... non-invasive determination of shallow subsurface hydrogeophysical properties at the field scale through the ... Therefore, quantifying the relative difference between the near-infrared reflectance 'peak' and the ... Logarithmic scale 10800 ohm.m. Data collected on the 4th April 2005 ...
ABSTRACT: Future Remote Sensing data will include hyperspectral data more and more. This study fr... more ABSTRACT: Future Remote Sensing data will include hyperspectral data more and more. This study frames in the preliminary studies to investigate the possibilities of these types of data. In this framework experimen-tal flights were organised by VITO (Flemish Institute for ...
ABSTRACT In this study it is shown how kriging with measurement errors (KME) is useful as opposed... more ABSTRACT In this study it is shown how kriging with measurement errors (KME) is useful as opposed to more conventional kriging methods. The goal of the study was to properly account for field measured soil electrical conductivity (EC) as soft data for the spatial prediction of soil salinity. Samplings were done in autumn 2009 (first dataset), spring and autumn 2010 (second and third datasets) around Uromieh Lake, northwest of Iran. The salinity was measured both in the field and laboratory for the first and second datasets. The first dataset was used for error measurements from which an error variance can be estimated. The measured errors were then used for characterizing probabilistic type soft data using the second dataset. The KME with only soft data (SKME), KME with both soft and hard data (HSKME) and ordinary kriging methods were compared. Validation criteria, mean error (ME) and mean squared error (MSE) were used for comparing the methods. Finally, the SKME method was applied as a way of improving the salinity prediction for the third dataset where only field measured soil salinity data were available. Comparing different kriging methods, Ordinary Kriging (OK) showed the best results among the comparing methods with ME and MSE equal to −0.12 and 0.55 respectively. SKME with ME equal to −0.13 was slightly different from OK and SKME with ME equal to −0.24 resulted in more bias predictions among others. KME method has shown to be useful for soil salinity monitoring and can effectively reduce sampling time.
Forest monitoring requires more automated systems to analyse the large amount of remote sensing d... more Forest monitoring requires more automated systems to analyse the large amount of remote sensing data. A new method of change detection is proposed for identifying forest land cover change using high spatial resolution satellite images. Combining the advantages of image segmentation, image differencing and stochastic analysis of the multispectral signal, this OB-Reflectance method is object-based and statistically driven. From a multidate image, a single segmentation using region-merging technique delineates multidate objects characterised by their reflectance differences statistics. Objects considered as outliers from multitemporal point of view are successfully discriminated thanks to a statistical procedure, i.e., the iterative trimming. Based on a chi-square test of hypothesis, abnormal values of reflectance differences statistics are identified and the corresponding objects are labelled as change. The object-based method performances were assessed using two sources of reference ...
We present an integrated modeling procedure for near-field ground-penetrating radar (GPR) and ele... more We present an integrated modeling procedure for near-field ground-penetrating radar (GPR) and electromagnetic induction (EMI) for the non-invasive determination of the constitutive properties of planar layered media in a high-resolution digital soil mapping framework. We validated the approach using GPR and EMI instruments set up using vector network analyzer technology, though the proposed methods also apply to conventional instruments. The antennas are modeled using a set of infinitesimal dipoles and characteristics, frequency-dependent, global reflection and transmission coefficients. The GPR and EMI antennas were calibrated using measurements at different heights over water. The electromagnetic models were then successfully validated using measurements acquired over water subject to different salinity levels. Finally, GPR and EMI data fusion strategies were investigated for resolving non-uniqueness issues that are inherent to multilayered media reconstruction
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Papers by Patrick Bogaert