Data Models for Moving Objects in Road Networks – Implementation and Experiences

Paper deals with the specific LBS scenario – Fleet management (FM) and more specifically with systems for Automatic vehicle location (AVL). Well designed and implemented spatial data model for moving objects is one of the most significant elements of any AVL system. In practical applications the results of the latest scientific research are seldom applied, despite the fact that this area has been developing intensively for more than 20 years. The reasons for this are analysed in the paper. Short analysis of functionality of these systems is presented considering the impact of these functionalities on the implemented data model for moving objects and more specifically their impact on spatio-temporal component of the model. The paper especially reviews the possibility of using road networks as a basis for the representation of moving objects data models and a fact that these models are rarely used in practical applications. A solution overcoming this situation is proposed. The solution assumes transition from the system that is not based on road network to the system that is based on network. There are quite few research papers dealing with OSM data models. Therefore, a significant space in this paper is dedicated to the description of these models since OSM data can be valuable for this type of applications

Airborne Laser Scanning (ALS) point cloud ground filtering for area of an active landslide (Doren, Western Austria)

Ground filtering of point cloud is the primary step required for Digital Terrain Model (DTM) generation. The procedure is especially interesting for forested areas, since LiDAR systems can measure terrain elevation under vegetation cover with a high level of penetration. This work analyzes the potential of ALS data ground filtering for area of an active landslide. The results of ALS filtering, for example, may improve geomorphological and motiondetection studies. ALS data was collected during flight campaign 2011 under leaf-off conditions for Doren region, Vorarlberg, Western Austria. In this area, non-ground objects are mostly low vegetation such as shrubs, small trees etc. The vegetation is more dense in lower part of the landslide where erosion is smaller. Vegetation points can be removed based on the hypothesis that these are significantly higher than their neighboring points. However, in case of steep terrain, ground points may have the same heights as vegetation points, and thus, local slope should be considered. Also, if terrain roughness increases, the classification may become even more complex. Software system OPALS (Orientation and Processing of Airborne Laser Scanning data, Vienna University of Technology) was used for processing the ALS data. Labeling ground points has been made using physical and geometrical attributes (parameters) of ALS points. Also additional attributes were calculated in order to improve extraction. Since bare ground surface is usually smooth and continuous unlike vegetation, standard deviation of local elevations was used as roughness measure to differentiate these surfaces. EchoRatio (ER) was adopted as a measure of surface penetrability, while number of echoes and differentiation between echoes (EchoNumber) were also deployed in filtering. Since the ground points are measurements from bare-earth that are usually the lowest surface features in a local area, normalized height was defined as a rank of neighboring points. Additionally, a so-called openness parameter was used as a convexity/concavity measure of surface. All of the mentioned point attributes have been combined in a decision tree in order to extract bare ground points. Based on a preliminary analysis, it is noted that implemented filtering procedure has difficulties with surfaces with rough terrain or steep relief. There is an assumption for lack of ground points in areas with dense vegetation that reduced the penetration of laser beams to the ground (lower part of a landslide). Also, points representing low vegetation were often labeled as ground points. Procedure produced holes in point cloud which demanded appropriate interpolation methods to be applied.Geophysical Research Abstract

New Downscaling Approach Using ESA CCI SM Products for Obtaining High Resolution Surface Soil Moisture

ESA CCI SM products have provided remotely-sensed surface soil moisture (SSM) content with the best spatial and temporal coverage thus far, although its output spatial resolution of 25 km is too coarse for many regional and local applications. The downscaling methodology presented in this paper improves ESA CCI SM spatial resolution to 1 km using two-step approach. The first step is used as a data engineering tool and its output is used as an input for the Random forest model in the second step. In addition to improvements in terms of spatial resolution, the approach also considers the problem of data gaps. The filling of these gaps is the initial step of the procedure, which in the end produces a continuous product in both temporal and spatial domains. The methodology uses combined active and passive ESA CCI SM products in addition to in situ soil moisture observations and the set of auxiliary downscaling predictors. The research tested several variants of Random forest models to determine the best combination of ESA CCI SM products. The conclusion is that synergic use of all ESA CCI SM products together with the auxiliary datasets in the downscaling procedure provides better results than using just one type of ESA CCI SM product alone. The methodology was applied for obtaining SSM maps for the area of California, USA during 2016. The accuracy of tested models was validated using five-fold cross-validation against in situ data and the best variation of model achieved RMSE, R2 and MAE of 0.0518 m3/m3, 0.7312 and 0.0374 m3/m3, respectively. The methodology proved to be useful for generating high-resolution SSM products, although additional improvements are necessary

Primena bliskopredmetne fotogrametrije za potrebe izrade geodetsko-tehničke dokumentacije objekata visokogradnje

Methods for application of digital photogrammetry for building surveying technical documentation for building constructions are considered in the paper. Based on our own and world-wide experiences, procedure for the production of surveying technical documentation in completely digital form is presented in the paper. The procedure of making technical documentation is divided in two logical phases. The first one is comprised of photographic recording, required field measurements and of making archive documentation. The second phase is comprised of making detailed geometric documentation, such as: precise digital orthophoto, 2D, 2.5D or 3D object model and the like, all in digital form. Considering that this phase is the most complex and the most expensive part of making technical documentation, it is not compulsory, but optional, i.e. if needed.U ovom radu se razmatraju načini primene digitalne fotogrametrije za potrebe formiranja geodetsko-tehničke dokumentacije za objekte visokogradnje. Na osnovu svetskih i sopstvenih iskustava u radu daje se prikaz procedure za izradu geodetsko-tehničke dokumentacije u potpuno digitalnom obliku. Postupak izrade tehničke dokumentacije je podeljen u dve logične faze. Prva se sastoji iz fotogrametrijskog snimanja, neophodnih terenskih merenja i izrade arhivske dokumentacije. Drugu fazu čini izrada detaljne geometrijske dokumentacije kao što su: precizni digitalni ortofoto, 2D, 2.5D ili 3D model objekta i slično, sve u digitalnom obliku. S obzirom da predstavlja najsloženiji i najskuplji deo izrade tehničke dokumentacije, ova faza se ne radi obavezno, nego po potrebi

Developing Serbian 3D Cadastre System - Challenges and Directions

The real estate cadastre in the Republic of Serbia is based on 2D cadastral maps and procedures that do not support unequivocal registration and visualization of complex 3D property situations or complex objects located on/below several parcels, especially in urban areas. Within this study, we analyzed and documented specific situations concerning registration challenges for the current cadastral system in the Republic of Serbia.Furthermore, the analysis of additional functionalities which will enable overcoming the limitations of the current cadastre in the short to the medium-termtime period is represented. Themain objective is to use the current cadastral data and procedures as far as possible in order to keep the transition smoother and economicallyfeasible. Having in mindthis objective,thevariation ofthe hybridapproach as the solution for Serbian 3D real estate cadastrewas analyzed. One of the preliminary assumptions of this research is that it is possible to develop a systemthat is simple enoughforimplementationand maintenance,but at the same comprehensive enough to overcome the difficulties ofthe current real estate cadastre.Within the case study,3D objects based ondata currently provided by licensed surveying agenciesare presented

Terrain Surface Modeling Using Triangular Spline Patches

Algorithms and software for digital terrain modeling using TIN based surface model are presented in the paper. Processing of all types of terrain surface data are supported: mass points, local extrema, contours, breaklines, structure lines, fault lines, etc. TIN topology and Bézier triangular surface patches are used for terrain surface reconstruction. Special attention is dedicated to the problem of respecting all implicit information about terrain surface that are contained within the input data. This is especially important in cases when terrain surface has to be reconstructed by using mostly contour data, since there are a lot of additional information that are implicitly contained within the data of this type. The software also contains functions for efficient verification of collected terrain data and DTM. Special consideration is given to the numerical procedures and algorithms aiming at providing contours and other outputs of DTM analysis of cartographic quality as required by many surveyors and their clients. The results of experiments demonstrated that the quality of terrain surface reconstruction from contours and/or other data using developed procedures and software is better, or at least as good as the quality achieved by using procedures and methods implemented within standard GIS/DTM software

Мобилно ласерско скенирање за детаљно дигитално топографско картирање

Mobile Laser Scanning (MLS) is a technique characterized by high data acquisition efficiency and level of detail. However, a lot of information contained in the LiDAR point cloud is only implicitly available. Therefore, in order to create a digital topographic map from a large quantity of MLS survey data, it is necessary to define a methodology that requires a combination of various software tools. In general, the applied methodology mainly depends on the final product specifications (data model, accuracy, level of detail, etc.). This paper describes the standard methodology of creating a detailed digital topographic map using data collected by MLS, which proved to be two times faster than the conventional methods (total station or GNSS survey)

Impact of New Technologies for Spatial Data Acquisition and Management on Land Consolidations in Serbia

Significant innovations and improvements in the technologies for spatial data acquisition and management data have emerged in the last few decades. Introduction of GPS and the technology of GIS and digital photogrammetry in surveying practice are definitely the most important ones. In spite of this, during the last few decades there were no actual projects of land consolidations in Serbia, so these advances in technology were not implemented within land consolidations and benefits were not obvious and quantified. However, in the last few years interest in land consolidations in Serbia has been intensified and a number of projects have been started and some were already finished using the latest technologies mentioned above. The role and impact of these technologies on all the relevant activities within major phases of land consolidation projects were analyzed and the resulting benefits were estimated and given in the paper. Improvements and benefits were estimated using data from a real land consolidation project. The benefits were expressed in terms of savings in time and costs and in terms of increased quality of the land consolidation results

Using nosql databases in the 3d cadastre domain

The 3D cadastre concept brings data models, which are more complex than traditional 2D cadastral data models and could be followed by a large amount of data. The 3D cadastral data should be stored in database management systems, since the cadastral data integrity and consistency have to be satisfied. Relational database management system requires a tabular structure where data are stored within predefined columns and data types, and this could be uncomfortable for 3D cadastre until relational provides full 3D support. This study examines the possibility of using NoSQL databases in the 3D cadastre domain. NoSQL database stores unstructured data, which means that it is not required to define in advance what data types and categories will be used. From the 3D cadastre point of view, the NoSQL approach provides flexibility in data types and allows easier implementation of the 3D cadastral models. The implementation is conducted by using MongoDB and 3D Cadastral Data Model, where 3D cadastral data, including both alphanumerical and geometry part of data, are prepared for importing and then stored, managed, queried, and updated within NoSQL database. Furthermore, data stored in MongoDB are visualized and queried inside a web browser by using Cesium library