Unmanned Aerial Vehicle (UAV) for monitoring soil erosion in Morocco

This article presents an environmental remote sensing application using a UAV that is specifically aimed at reducing the data gap between field scale and satellite scale in soil erosion monitoring in Morocco. A fixed-wing aircraft type Sirius I (MAVinci, Germany) equipped with a digital system camera (Panasonic) is employed. UAV surveys are conducted over different study sites with varying extents and flying heights in order to provide both very high resolution site-specific data and lower-resolution overviews, thus fully exploiting the large potential of the chosen UAV for multi-scale mapping purposes. Depending on the scale and area coverage, two different approaches for georeferencing are used, based on high-precision GCPs or the UAV’s log file with exterior orientation values respectively. The photogrammetric image processing enables the creation of Digital Terrain Models (DTMs) and ortho-image mosaics with very high resolution on a sub-decimetre level. The created data products were used for quantifying gully and badland erosion in 2D and 3D as well as for the analysis of the surrounding areas and landscape development for larger extents

Monitoring soil erosion in the Souss basin, Morocco, with a multiscale object-based remote sensing approach using UAV and satellite data

This article presents a multiscale approach for detecting and monitoring soil erosion phenomena (i.e. gully erosion) in the agro-industrial area around the city of Taroudannt, Souss basin, Morocco. The study area is characterized as semi-arid with an annual average precipitation of 200 mm. Water scarcity, high population dynamics and changing land use towards huge areas of irrigation farming present numerous threats to sustainability. The agro-industry produces citrus fruits and vegetables in monocropping, mainly for the European market. Badland areas strongly affected by gully erosion border the agricultural areas as well as residential areas. To counteract the significant loss of land, land-leveling measures are attempted to create space for plantations and greenhouses. In order to develop sustainable approaches to limit gully growth the detection and monitoring of gully systems is fundamental. Specific gully sites are monitored with unmanned aerial vehicle (UAV) taking small-format aerial photographs (SFAP). This enables extremely high-resolution analysis (SFAP resolution: 2-10 cm) of the actual size of the gully channels as well as a detailed continued surveillance of their growth. Transferring the methodology on a larger scale using Quickbird satellite data (resolution: 60 cm) leads to the possibility of a large-scale analysis of the whole area around the city of Taroudannt (Area extent: ca. 350 km²). The results will then reveal possible relationships of gully growth and agro-industrial management and may even illustrate further interdependencies. The main objective is the identification of areas with high gully-erosion risk due to non-sustainable land use and the development of mitigation strategies for the study area

An object-based classification approach for mapping "migrant housing" in the mega-urban area of the Pearl River Delta (China)

Urban areas develop on formal and informal levels. Informal development is often highly dynamic, leading to a lag of spatial information about urban structure types. In this work, an object-based remote sensing approach will be presented to map the migrant housing urban structure type in the Pearl River Delta, China. SPOT5 data were utilized for the classification (auxiliary data, particularly up-to-date cadastral data, were not available). A hierarchically structured classification process was used to create (spectral) independence from single satellite scenes and to arrive at a transferrable classification process. Using the presented classification approach, an overall classification accuracy of migrant housing of 68.0% is attained

Population estimation in urban areas based on "mixed/cross" stereo models

In the project X3D4Pop we investigate if "mixed" satellite image pairs acquired on two different dates can be used to calculate meaningful building heights in urban areas. Based on These results, the dependency of urban population estimation models on the availability and quality of 3D data is tested. Study areas are Port-au-Prince and Salzburg. The 3D-models are validated against LiDAR-derived elevation models, population numbers are compared with rastered population data from Statistik Austria. The project explores first steps towards an urban population estimation Service by remote sensing, for the humanitarian community

A Proposal for Mapping Historic Irrigation Channels to Reveal Insights into Agro-Climatic Systems: A Case Study in Upper Austria. GI_Forum 2013 – Creating the GISociety|

Recently, the remains of two historic irrigation channels were re-discovered in the Upper Austrian municipality of Regau. Since the current average precipitation in the region is sufficient to sustain a productive agricultural land use, the irrigation channels raise several questions related to climate variability. To verify different hypotheses such as the construction as a response to a changing climate or the assumed purpose of grassland irrigation, potential coherences are discussed. In addition, remote sensing techniques for the detection of hidden structures overprinted by physical and human activities are outlined. The analysis of available references enables a first assessment of the channels purpose. Several indicators such as the shape and incline of the remaining topographic imprints support the hypothesis of their irrigation function. Furthermore, the qualitative analysis of today’s agro-climatic conditions reveals the general vulnerability of the system to climate changes. Moreover, a dendrochronological analysis shows a phase of remarkable climate variability in conjunction with significant drying periods throughout the 3rd and 4th century. This may have posed a reason for the construction of the irrigation system. Further research is necessary to verify the possible alternative hypothesis, which suggests grassland fertilization as the main irrigation purpose. Therefore, a long term analysis of water nutrient contents is required. Moreover, the application of remote sensing techniques may help to identify the extent of the formerly irrigated area

A Proposal for Mapping Historic Irrigation Channels to Reveal Insights into Agro-Climatic Systems: A Case Study in Upper Austria. GI_Forum 2013 – Creating the GISociety|

Recently, the remains of two historic irrigation channels were re-discovered in the Upper Austrian municipality of Regau. Since the current average precipitation in the region is sufficient to sustain a productive agricultural land use, the irrigation channels raise several questions related to climate variability. To verify different hypotheses such as the construction as a response to a changing climate or the assumed purpose of grassland irrigation, potential coherences are discussed. In addition, remote sensing techniques for the detection of hidden structures overprinted by physical and human activities are outlined. The analysis of available references enables a first assessment of the channels purpose. Several indicators such as the shape and incline of the remaining topographic imprints support the hypothesis of their irrigation function. Furthermore, the qualitative analysis of today’s agro-climatic conditions reveals the general vulnerability of the system to climate changes. Moreover, a dendrochronological analysis shows a phase of remarkable climate variability in conjunction with significant drying periods throughout the 3rd and 4th century. This may have posed a reason for the construction of the irrigation system. Further research is necessary to verify the possible alternative hypothesis, which suggests grassland fertilization as the main irrigation purpose. Therefore, a long term analysis of water nutrient contents is required. Moreover, the application of remote sensing techniques may help to identify the extent of the formerly irrigated area

Detection of Gully-Affected Areas by Applying Object-Based Image Analysis (OBIA) in the Region of Taroudannt, Morocco

This study aims at the detection of gully-affected areas by applying object-based image analysis in the region of Taroudannt, Morocco, which is highly affected by gully erosion while simultaneously  representing a major region of agro-industry with a high demand of arable land. As high-resolution optical satellite data are readily available from various sensors and with a much better temporal resolution than 3D terrain data, an area-wide mapping approach to extract gully-affected areas using only optical satellite imagery was developed. The methodology additionally incorporates expert knowledge and freely-available vector data in a cyclic object-based image analysis approach. This connects the two fields of geomorphology and remote sensing. The classification results show the successful implementation of the developed approach and allow conclusions on the current distribution of gullies. The results of the classification were checked against manually delineated reference data incorporating expert knowledge based on several field campaigns in the area, resulting in an overall classification accuracy of 62%. The error of omission accounts for 38% and the error of commission for 16%, respectively. Additionally, a manual assessment was carried out to assess the quality of the applied classification algorithm. The limited error of omission contributes with 23% to the overall error of omission and the limited error of commission contributes with 98% to the overall error of commission. This assessment improves the results and confirms the high quality of the developed approach for area-wide mapping of gully-affected areas in larger regions. In the field of landform mapping, the overall quality of the classification results is often assessed with more than one method to incorporate all aspects adequately

Processing of extremely high resolution LiDAR and RGB data: outcome of the 2015 IEEE GRSS data fusion contest—Part B: 3-D Contest

In this paper, we report the outcomes of the 2015 data fusion contest organized by the Image Analysis and Data Fusion Technical Committee (IADF TC) of the IEEE Geoscience and Remote Sensing Society. As for previous years, the IADF TC organized a data fusion contest aiming at fostering new ideas and solutions for multisource studies. The 2015 edition of the contest proposed a multiresolution and multisensorial challenge involving extremely high resolution RGB images (with a ground sample distance of 5 cm) and a 3-D light detection and ranging point cloud (with a point cloud density of approximatively 65 pts/m2 ). The competition was framed in two parallel tracks, considering 2-D and 3-D products, respectively. In this Part B, we report the results obtained by the winners of the 3-D contest, which explored challenging tasks of road extraction and ISO containers identification, respectively. The 2-D part of the contest and a detailed presentation of the dataset are discussed in Part A

AGIT Journal für Angewandte Geoinformatik / Bevölkerungsabschätzung in Städten anhand von Stereo-Bildpaarungen, di e nicht am selben Tag aufgenommen wurden

Im Projekt X3D4Pop wird untersucht, inwiefern Bildpaare, die an unterschiedlichen Tagen aufgenommen wurden, geeignet sind, um daraus brauchbare Höheninformation von Gebäuden in Städten abzuleiten. Darauf aufbauend wird getestet, wie stark die Abschätzung der Bevölkerungszahl von der Verfügbarkeit von 3D-Daten abhängt. Testgebiete sind Salzburg und Port-au-Prince. Als Referenz dienen aus LiDAR-Daten abgeleitete Höhenmodelle sowie gerasterte Bevölkerungsdaten von Statistik Austria. Ziel ist, die Arbeitsabläufe eines Services zur urbanen Bevölkerungsabschätzung basierend auf Fernerkundungsdaten für humanitäre Organisationen zu entwickeln.In the project X3D4Pop we investigate if “mixed” satellite image pairs acquired on two different dates can be used to calculate meaningful building heights in urban areas. Based on These results, the dependency of urban population estimation models on the availability and quality of 3D data is tested. Study areas are Port-au-Prince and Salzburg. The 3D-models are validated against LiDAR-derived elevation models, population numbers are compared with rastered population data from Statistik Austria. The project explores first steps towards an urban population estimation Service by remote sensing, for the humanitarian community.(VLID)448205