Integration, Processing and Dissemination of LiDAR Data in a 3D Web-GIS

The rapid increase in applications of Light Detection and Ranging (LiDAR) scanners, followed by the development of various methods that are dedicated for survey data processing, visualization, and dissemination constituted the need of new open standards for storage and online distribution of collected three-dimensional data. However, over a decade of research in the area has resulted in a number of incompatible solutions that offer their own ways of disseminating results of LiDAR surveys (be it point clouds or reconstructed three-dimensional (3D) models) over the web. The article presents a unified system for remote processing, storage, visualization, and dissemination of 3D LiDAR survey data, including 3D model reconstruction. It is built with the use of open source technologies and employs open standards, such as 3D Tiles, LASer (LAS), and Object (OBJ) for data distribution. The system has been deployed for automatic organization, processing, and dissemination of LiDAR surveys that were performed in the city of Gdansk. The performance of the system has been measured using a selection of LiDAR datasets of various sizes. The system has shown to considerably simplify the process of data organization and integration, while also delivering tools for easy discovery, inspection, and acquisition of desired datasets.

Międzyuczelniany kierunek studiów technologie kosmiczne i satelitarne - edycja trzecia

politechnika gdańska już po raz trzeci rekrutuje kandydatów na interdyscyplinarny kierunek studiów II stopnia - technologie kosmiczne i satelitarne (TKiS). Jak w latach poprzednich, studia organizowane są we współpracy z Uniwersytetem Morskim w Gdyni oraz Akademią Marynarki Wojennej w Gdyni. Od tego roku akademickiego w przedsięwzięciu weźmie udział także Uniwersytet Gdański. W poprzednich latach studenci osiągnęli wiele sukcesów w ramach zespołów oraz kół naukowych. Mieli także możliwość kontaktu z ekspertami z krajowego rynku pracy, w tym przedstawicieli z sektora kosmicznego.

Three Editions of Inter-University Studies on Space and Satellite Technology. Candidate and/vs. Graduate, a Case Study

Currently, there is a growing demand for most up-to-date academic courses that will fulfil the needs of modern society. Each candidate has to make choices and judgements carefully, in order to succeed on the market. This is particularly important when educating individuals with different backgrounds, especially on an inter-university course in the field of space sciences and technology. This paper describes a case study carried out on a group of candidates and graduates from different editions of Space and Satellite Technologies interdisciplinary master studies at Gdansk University of Technology as well as two maritime universities in Gdynia. The education process itself is realized in cooperation with business partners. The paper provides both qualitative and quantitative data, considering the whole group and particular individuals. In addition, some examples of individual achievements of outstanding students are presented.

3D Object Shape Reconstruction from Underwater Multibeam Data and Over Ground Lidar Scanning

The technologies of sonar and laser scanning are an efficient and widely used source of spatial information with regards to underwater and over ground environment respectively. The measurement data are usually available in the form of groups of separate points located irregularly in three-dimensional space, known as point clouds. This data model has known disadvantages, therefore in many applications a different form of representation, i.e. 3D surfaces composed of edges and facets, is preferred with respect to the terrain or seabed surface relief as well as various objects shape. In the paper, the authors propose a new approach to 3D shape reconstruction from both multibeam and LiDAR measurements. It is based on a multiple-step and to some extent adaptive process, in which the chosen set and sequence of particular stages may depend on a current type and characteristic features of the processed data. The processing scheme includes: 1) pre-processing which may include noise reduction, rasterization and pre-classification, 2) detection and separation of objects for dedicated processing (e.g. steep walls, masts), and 3) surface reconstruction in 3D by point cloud triangulation and with the aid of several dedicated procedures. The benefits of using the proposed methods, including algorithms for detecting various features and improving the regularity of the data structure, are presented and discussed. Several different shape reconstruction algorithms were tested in combination with the proposed data processing methods and the strengths and weaknesses of each algorithm were highlighted.

Seafloor Characterisation Using Underwater Acoustic Devices

The problem of seafloor characterisation is important in the context of management as well as investigation and protection of the marine environment. In the first part of the paper, a review of underwater acoustic technology and methodology used in seafloor characterisation is presented. It consists of the techniques based on the use of singlebeam echosounders and seismic sources, along with those developed for the use of sidescan and multibeam sonar systems. In the second part, the review is followed by a description of the combined approach to seafloor characterisation developed by the authors. It is based on extraction of three types of information from multibeam sonar recordings, namely: 1) the sonar image of seabed surface, 2) the point cloud describing seabed surface shape, 3) the set of echo envelopes corresponding to particular sonar beams. Then the seafloor classification is performed using the set of parameters (descriptors) which are calculated on the basis of 3 types of sonar data mentioned above. The proposed approach has been tested using field sonar data recordings in the water region of the Southern Baltic Sea. In this region, four sites differing by seabed type were investigated.

“Space & Satellite Technologies" intercollegiate master-degree courses of study in Tri-City (Poland)

Since summer semester of the academic year 2016/2017, two faculties of Gdansk University of Technology GUT (Faculty of Mechanical Engineering and Faculty of Electronics, Telecommunications and Informatics) together with the Gdynia Maritime University (Faculty of Electronics) and the Polish Naval Academy in Gdynia (Faculty of Command and Naval Operations) have opened intercollegiate master - degree studies called: Space and Satellite Technologies (TKiS). Each of these faculties offer for their candidates and conduct special education in case of certain speciality. This initiative is supported by Polish Space Agency and received additional funding from the National Centre for Research and Development. Under the project entitled: Adaptation of the second -degree studies Space and Satellite Technologies, to the needs of the labor market, people involved in the space industry were included in the didactics.

Multibeam data processing for 3D object shape reconstruction

The technology of hydroacoustic scanning offers an efficient and widely-used source of geospatial information regarding underwater environments, providing measurement data which usually have the structure of irregular groups of points known as point clouds. Since this data model has known disadvantages, a different form of representation based on representing surfaces with simple geometric structures, such as edges and facets, is preferred for data featuring seabed surface relief and various underwater objects. In this paper, the authors propose a multiple-step approach to three-dimensional surface reconstruction from multibeam sonar measurements, relying on the proper application of various algorithms for noise reduction, data rasterization and classification. The results obtained by combining several different surface reconstruction algorithms with the proposed data processing technique were tested, and the strengths and weaknesses of each method were highlighted.

Multibeam Sonar Data Processing for Seafloor Classification

Despite many years of the development of methodology for sensing the seafloor by means of underwater acoustics, the currently used techniques are still not mature enough and not ready to be utilised in numerous different (i.e. with respect to a water region character, used equipment type etc.) tasks. Therefore the hydroacoustic methods, both utilising vertical observations (e.g. by singlebeam echosounders), as well as those relying on wide-angle sensing (by sidescan sonars and multibeam sonars), are still the subject of extensive research. In this paper, after a short review on underwater acoustic equipment and methodology used nowadays in seafloor characterisation, the concept and the results of a combined method of multibeam sonar data processing for seabed classification are presented.

On Algorithm Details in Multibeam Seafloor Classification

Remote sensing of the seafloor constitutes an important topic in exploration, management, protection and other investigations of the marine environment. In the paper, a combined approach to seafloor characterisation is presented. It relies on calculation of several descriptors related to seabed type using three different types of multibeam sonar data obtained during seafloor sensing, viz.: 1) the grey-level sonar images (echograms) of the seabed, 2) the 3D model of the seabed surface which consists of bathymetric data, 3) the set of time domain bottom echo envelopes received in the consecutive sonar beams. The proposed methodology has been tested using field data records acquired from several bottom types in the Southern Baltic Sea. Using the examples of particular parameters, the influence on the specific manner and details regarding their calculation, i.e. the size of the applied current local window to a sonar image, on the obtained classification performance, is discussed.

Optimized AVHRR land surface temperature downscaling method for local scale observations: case study for the coastal area of the Gulf of Gdańsk

Satellite imaging systems have known limitations regarding their spatial and temporal resolution. The approaches based on subpixel mapping of the Earth’s environment, which rely on combining the data retrieved from sensors of higher temporal and lower spatial resolution with the data characterized by lower temporal but higher spatial resolution, are of considerable interest. The paper presents the downscaling process of the land surface temperature (LST) derived from low resolution imagery acquired by the Advanced Very High Resolution Radiometer (AVHRR), using the inverse technique. The effective emissivity derived from another data source is used as a quantity describing thermal properties of the terrain in higher resolution, and allows the downsampling of low spatial resolution LST images. The authors propose an optimized downscaling method formulated as the inverse problem and show that the proposed approach yields better results than the use of other downsampling methods. The proposed method aims to find estimation of high spatial resolution LST data by minimizing the global error of the downscaling. In particular, for the investigated region of the Gulf of Gdansk, the RMSE between the AVHRR image downscaled by the proposed method and the Landsat 8 LST reference image was 2.255°C with correlation coefficient R equal to 0.828 and Bias = 0.557°C. For comparison, using the PBIM method, it was obtained RMSE = 2.832°C, R = 0.775 and Bias = 0.997°C for the same satellite scene. It also has been shown that the obtained results are also good in local scale and can be used for areas much smaller than the entire satellite imagery scene, depicting diverse biophysical conditions. Specifically, for the analyzed set of small sub-datasets of the whole scene, the obtained RSME between the downscaled and reference image was smaller, by approx. 0.53°C on average, in the case of applying the proposed method than in the case of using the PBIM method.