Displays

Suspended particulate matter (SPM) plays a fundamental role in the impact and eventual fate of sediment, pollutants, pathogens, nutrients and manufactured nano-materials in aquatic environments. SPM usually exists in aquatic systems as flocs; complex, fragile and loosely-bound aggregates of fine sediment particles, bacteria, organic matter and fluid-filled pore space. Floc settling velocity is widely considered to be the most important dynamic characteristic that determines SPM fate and transport, and is dependent on the size, shape, density, porosity, fractal dimension and composition of the flocs formed in suspension. Of these characteristics, floc density and porosity are thought to exert the greatest impact on settling velocity, yet neither parameter can currently be measured. As such, transport model parameters are typically estimated from Stokes’ Law, based on an assumption of a spherical shape for the floc. Due to a lack of available observational data, such assumptions cannot be validated and porosity is often omitted with flocs treated as essentially impermeable spherical entities, despite pores accounting for much of the defined ‘floc-space’ (often estimated to be > 90% within larger macro-flocs).

As part of a wider project exploring the 3D nature of floc structure and dynamics (NERC-3D Flocs), this study reports a first application of high-resolution 3D X-Ray microtomography on populations of flocs, offering a method that quantifies 3D floc porosity based on observation rather than assumption of floc structural properties. High resolution (3 µm voxel size) scans of both laboratory-generated and natural floc populations, from which sub-populations of different-sized micro- and macro-flocs (30 in each of 5 size categories for each floc population) are extracted. A data-processing workflow is presented which applies 3D morphological filters to systematically define a realistic expression of the total pore-space associated with individual flocs. Floc pore-space is further partitioned into isolated and effective pores, based on a 12 µm pore throat diameter threshold below which fluid flow is hydrodynamically minimal. Analysis of these realistic floc porosity data populations indicates that previous assumptions of floc porosity lack meaning in terms of settling dynamics. Substitution with meaningful, realistic floc porosity will have a significant impact on the prediction of floc settling velocity within SPM sediment transport models. 

How to cite: Carr, S., Lawrence, T., Spencer, K., Manning, A., Wheatland, J., and Bushby, A.: Realistic estimates of floc porosity based on high resolution 3D X-Ray microtomography, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-7725, https://doi.org/10.5194/egusphere-egu2020-7725, 2020.

Within coastal and estuarine environments suspended cohesive sediments that are often closely associated with carbon, nutrients, pathogens and pollutants form aggregates commonly known as ‘flocs’. Understanding the settling dynamics and eventual fate of flocculated sediment is therefore a major issue for the management of aquatic environments. Several factors have been reported to influence the hydrodynamic behaviour of flocs, including size, shape, density and porosity. Recent evidence suggests that of these shape exerts the greatest influence on settling rates. Yet means of characterising shape have been limited to easy to measure quantities such as fractal dimension and circularity measured in 2-dimensions (2D) that fail to capture the highly complex, irregular geometries of sediment flocs. However, recent improvements in sampling methods, 3D imaging capabilities and data processing software enable for the first time the characterisation of flocs based on their 3D morphology.

This study compares the morphologies of natural and artificial flocs generated under different environmental conditions. By employing a novel apparatus for the capture, immobilisation and handling of delicate floc samples, 3D X-ray micro-computed tomography (X-ray µCT) scans are successfully obtained and used to derive accurate volumetric reconstructions of tens of thousands of individual flocs. Using these datasets we compare different methods for describing shape, and test these for their ability to predict floc settling behaviours.

How to cite: Wheatland, J., Spencer, K., Grieve, S., Gu, C., Carr, S., Manning, A., Bushby, A., and Botto, L.: A New 3D Descriptor for Irregularly Shaped Suspended Sediment Aggregates, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-11673, https://doi.org/10.5194/egusphere-egu2020-11673, 2020.

Representatives of the scientific community collect and store huge amounts of spatial data resulting from years of their studies. However, there is a common problem of visualization methods of data which would be interesting to understand for a recipient from outside of the area as well as according to the current trends. In the modern day, many spheres of our life have been moved to the virtual reality and that is why representatives of areas such as industry, science, culture and art need to deal with the representation of the real world in a 3D reality.

This work is concerned with the current issue of visualization of spatial data collected by surveyors as well as representatives of many other areas. The proposed method of presentation of collected research data is not only low-cost at preparation but is also distinguished by its simplicity of implementation. Its functionality will be presented by using an example of the Agora area located in the Archaeological Park of Kato Paphos in Cyprus. The mentioned area was created in order to protect and promote the archaeological sites as well as the artefacts from the former epoch which have been found in the area. Such historic places are very often not fully available to see by visitors and that is why the documentation and visualization of them in 3D reality might be incredibly helpful. This kind of activity not only contributes to the popularization of archaeological research but also meets the expectations of a modern recipient who uses virtual reality more and more often in order to learn about new places. It is worth mentioning that the presented visualization of measurement data is a versatile method that is intended to be used in many different scientific and research areas.

From a technical point of view, the presented work guides a recipient through the complete process of development of an advanced animation in the environment used in the creation of 3D computer games – the game engine Unity. In the first part of the article the suitability of the data results obtained in digital photogrammetry as well as laser scanning was estimated for purposes of applying the presented method. The work also brings up the issues of limitation of free software and raises a question of methods allowing to meet the requirements with minimized loss of quality and accuracy of the data. The next step was to present the method of importing data (a mesh model and a high-resolution texture). Operating mechanism in Unity as well as a transfer of interactive visualization into the online browser Unity Connect were discussed in the further part of the article. It is worth mentioning that thanks to the FPP (First Person Perspective) technique the developed visualization allows a user to be transferred right into the centre of the archaeological sites where the admission for the third party is usually significantly restricted.

How to cite: Janos, D., Ruchała, J., Puniach, E., and Ćwiąkała, P.: Unity game engine as a method of presentation of data collected from UAV, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-11970, https://doi.org/10.5194/egusphere-egu2020-11970, 2020.

Unmanned Aerial Vehicles (UAV) are currently one of the most popular methods of colleting photogrammetric data. A short time of data acquisition and low costs are the key advantages of this solution, especially important during cyclical measurements of various types of objects.

The aim of this paper is to assess the possibility of using images obtained from UAV to determine the deformation of earth structures. The object of measurement was Krakus Mound located in Cracow (Poland). It is one of the oldest mounds in Cracow, preserved to this day. The history of this hill is unknown but it is assumed that the mound was built in stages. In 2013, the site was renovated.

As a part of the research, between 2015 and 2019, cyclic photogrammetric flights were carried out over Krakus Mound. For this purpose, DJI S900 aircraft equipped with a non-metric visible light camera Sony Alpha a6000 was used. The measurements were taken every year in spring and autumn. In total, 7 measurement sessions were performed, during which the coordinates of ground control points and check points were measured each time. As part of fieldwork, numerous comparative measurements were also carried out using other surveying instruments, such as GNSS receivers, total stations and terrestrial laser scanner.

This paper presents the results of research aimed at observing the geometry of the mound in 2015-2019. Low-altitude images obtained in combination with the Structure from Motion technique allowed to generate photogrammetric products to determine the deformation of the object. Generated UAV-derived point clouds and digital terrain models were used for the analyses. They were compared with reference data, i.e. photogrammetric products created on the basis of data obtaining during the first UAV flight and the results of total station and satellite measurements. This made it possible to determine the influence of the low vegetation on the results of measurements and to check whether the object is deforming. The research also included terrestrial laser scanning of the mound and usage of available LiDAR data to compare scanning data with low-altitude photogrammetric products. Numerous analyses allowed to create methodology of inventory measurements of earth structure covered with low vegetation using UAV-based photogrammetry. 

How to cite: Bochniarz, A., Wójcik, A., Puniach, E., and Ćwiąkała, P.: Application of UAV in measurements of earth structure deformation , EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-12048, https://doi.org/10.5194/egusphere-egu2020-12048, 2020.

            With the technological progress, the demand for a three-dimensional presentation of the world around us is growing. Currently, modelling of urban space in 3d based on presenting it as simple geometric solids is not able to satisfy the needs of the constantly growing market. There are also noticeable trends aimed at representing the real world as faithfully as possible in virtual space.

            The purpose of this work is to show the differences between the individual levels of detail (LoD) of the building facade model obtained using classic geodetic measurements as well as ground photogrammetry and UAV photogrammetry. For this purpose, pictures of the building facade were taken and its characteristic elements were measured so that the generated model was metric.

            Creating a vector model of the facade consisted in modelling individual blocks based on points obtained from the total station measurement. The model was generalized for individual levels of detail using fewer points to make it. Subsequently, vector models were textured by photos.

In addition, oblique facade photos were developed, and then a triangular mesh model was made from the dense point cloud generated on their basis. The model was analyzed for meeting the accuracy criteria of individual LoDs in order to determine whether the use of only photogrammetric data allows the generation of a suitably detailed spatial model.

The resulting models were compared with each other, thanks to which it is possible to verify whether the facade is symmetrical and how repeatable its architectural elements are. The outcome also enables the assessment of the accuracy with which the building elements should be measured in order to obtain a reliable model that meets the criteria of the assumed LoD level for the resulting product.

How to cite: Dziok, W., Jasińska, A., Puniach, E., and Ćwiąkała, P.: Generation of 3D building model using different LoD, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-16720, https://doi.org/10.5194/egusphere-egu2020-16720, 2020.

Immersive Technology has been widely discussed in various applications; the development of this technology creates an experience which is not possible in our physical reality. The rapid development of computer software and hardware makes the 3D visualisation and simulation of real-world scenarios could be represented in much higher resolutions. Recent studies show that visualising natural disasters immersively could be beneficial to increase people’s awareness and prepare the public for future event. In a recent research project, we visualized and simulated a flooding event, Storm Frank, in 2015 and its damage to the local residence of a town called Ballater outside Aberdeen, UK on Virtual Reality form. To provide accurate simulation, topographic data and real-world environmental data such as weather, rainfalls, river level data etc., are applied and analysed in this project. This immersive experience provides significant opportunities for effective communication among all users. The project used 3D modelling and simulation of the flooding encompasses the development and exemplification of the model of the town and real scenario flooding event, retrieving data from various sources such as geographical data and environment data. The gamification of this application shows great potential to be used for public engagement event, policy making and educational purposes. 

How to cite: Jiang, Y., Alza Santos, J., Wang, C., and Mabon, L.: Immersive Flooding Event Simulation for Climate Resilience Analysis, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-18273, https://doi.org/10.5194/egusphere-egu2020-18273, 2020.

The Rhine-Ruhr region is located in the state of North Rhine-Westphalia (NRW) in western Germany. Due to the transition from coal to low-carbon heat sources, potential locations in NRW must be explored regarding to their geothermal potential. The Bavarian area has shown for the last 20 years, that deep geothermal energy is both feasible and economical in Germany. Compared to the mentioned Molasse basin in south Germany, the geological setting is much more complex in the Rhine-Ruhr region. Based on a typical geothermal gradient of 30 °C/km, the optimal depth of a reservoir should be between 3000 m to 5000 m. In this depth, carbonate layers from Devonian times were identified in NRW. Due to the lack of accessibility, minor reservoir characterization was done, yet. Therefore, a geological model which reflects local lithological properties is essential for further geothermal projects. The model of the Rhine-Ruhr region is based on field surveys, top formations, geological sections and maps, respectively. The geometrical model is supplemented by rock properties, like density, porosity, and P- respectively S-wave velocities. These properties are derived from well logs, laboratory measurements and literature, transferring the derived properties to the grid require an analysis of upscaling techniques and distribution of such properties in the model. The result is a heterogeneous model representing the geological structure and rock property distribution of the Rhine-Ruhr region. Representative lithological units like Ruhrsandstone or interbedded coal, clay, and sandstone strata are also implemented as dominant fracture orientations. In this work we are considering several parameters to find a balance between the resolution of the model, property scaling and computational efficiency. One key aspect is that geological models are built with irregular grids while for our wave propagation simulations a regular and cartesian grid with equal grid spacing is required. Of course, such regular grids can be used for several modelling techniques and can be used as a basis for different studies. Overall goal is to evaluate local geological models to assess the feasibility of geothermal projects in the area.

How to cite: Gonzalez de Lucio, G. D. L. A., Balcewicz, M., and Saenger, E. H.: Establishing a 3D model for the Rhine-Ruhr region based on the geology and property distribution., EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-20592, https://doi.org/10.5194/egusphere-egu2020-20592, 2020.

Digital terrain model (DTM) reconstruction in coral reef environments through traditional mapping methods, using either singlebeam or multibeam echosounder systems, often presents difficulties in obtaining a continuous 3-dimensional representation, due to the complex topography and the considerable extension of very shallow areas (i.e. reef flat areas). The present-day most advanced techniques used to collect high-resolution elevation data both for land surface and the seafloor, in coral reef environments, include the use of satellite-derived bathymetry, LIDAR technology, Unmanned Aerial Vehicles coupled with photogrammetry and traditional bathymetric surveys. Data processing represents in all the cases a fundamental step for ensuring the accuracy and reliability of obtained measurements, especially for allowing a precise integration of all data sources into a continuous DTM. In our work, we present a tested methodological protocol for the generation of a continuous fine-scale digital terrain model (DTM) in coral reef environments. A portion of an atoll reef (Magoodhoo reef located in the Maldivian archipelago, the southern part of Faafu atoll) has been remotely mapped from the reef flat area to the connected and deeper lagoon environment, collecting elevation data by different sources according to the surveyed depths. In particular, we acquired acoustic depth measurements using a multibeam echosounder and 3D point clouds applying the Structure from Motion (SfM) technique to RGB images, collected using an Unmanned Aerial Vehicle (UAV). All obtained data were calibrated and validated with RTK-GNSS measurements and successfully integrated in order to generate a harmonized DTM for the surveyed sector of the Magoodhoo reef.

How to cite: Savini, A., Marchese, F., Fallati, L., Corselli, C., and Galli, P.: Integrating acoustics and photogrammetry-based 3D point clouds for the generation of a continuous bathymetric model in coral reef environment., EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-22054, https://doi.org/10.5194/egusphere-egu2020-22054, 2020.