Maanmittauslaitos: Recent submissions

Now showing items 1-20 of 412
  • Kirkko-Jaakkola, Martti; Marila, Simo; Sarang, Thombre; Honkala, Salomon; Koivula, Hannu; Kuusniemi, Heidi; Söderholm, Stefan (2019)
    Proceedings of the 32nd International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS+ 2019) September 16 - 20, 2019, Hyatt Regency Miami, Miami, Florida
    This paper presents a hybrid navigation algorithm based on loose coupling of the on-board speedometer and inertial sensors of a land vehicle with a GNSS receiver. An Extended Kalman Filter estimating ten error states is used as the hybridization framework. The algorithm is developed to serve as a baseline for the evaluation of the navigation infrastructure of the Aurora ecosystem which is an Arctic test bed for autonomous vehicles and intelligent transport systems. In the experimental tests we focus on the performance of the navigation algorithm during GNSS outages. First, the tests indicate that the quality of GNSS updates has an immediate effect on how fast the position errors accumulate when GNSS becomes unavailable. Second, using low-cost sensors together with the current navigation infrastructure available at the Aurora test site, GNSS position fixes need to be obtained at intervals no longer than 4 seconds in order to maintain a 95 % horizontal positioning accuracy better than 0.2 meters. The results serve as a basis for recommendations for further development of the Aurora ecosystem, suggesting that further positioning infrastructure could be deployed for guaranteeing a navigation performance adequate for autonomous vehicles.
  • Perheentupa, Viljami; Mäkinen, Ville; Habicht, Hando-Laur; Oksanen, Juha (Elsevier, 2020)
    Applied Computing and Geosciences
    Post-glacial land uplift and shore displacement are dynamic processes that are challenging to present with cartography and geovisualization. To communicate these phenomena, we have created a dynamic visualization in the form of high-quality animation, utilizing automated processes in the computation and rendering of large raster datasets. We have developed a simplified model to assess the past and future elevation models, and applied it to the High Coast/Kvarken Archipelago UNESCO World Heritage Site, which is considered one of the best places in the world to observe land uplift. Additionally, the ice decline in the area has been evaluated and visualized. Based on the model and the present-day topography/bathymetry data, we provide a 40 fps 4K-resolution animation with an 80-s duration of the post-glacial history at the World Heritage Site and its vicinity, extending from 10,500 years ago to 1000 years in the future. Although they do not aim to contain the precision of thorough paleogeographic reconstructions, we have found that the individual frames of the animation are closely aligned with comparable geological data. We also present the computational process flow and the visualization principles used in the automated rendering, and thus aim to contribute to the cartographic presentation of geodynamic processes.
  • Kettunen, Pyry; Koski, Christian; Rönneberg, Mikko; Oksanen, Juha; Hansen, Henning Sten; Schrøder, Lise (2020)
    BONUS BASMATI
    This deliverable presents Baltic Explorer, a collaborative GIS and spatial decision support system (SDSS) for the maritime spatial planning (MSP), that was designed, built, and studied in the BONUS BASMATI Work Package 5. Sec-tion 1 summarises the general concept, key functionalities, use tests and free release of the Baltic Explorer, and Sec-tion 2 describes and guides the usage of the system. Previ-ous deliverables and published or forthcoming scientific articles provide more information about the creation and assessment of the Baltic Explorer. Baltic Explorer is available for use at http://balticexplorer.eu and its source code at https://github.com/FGI-GEOINFO/Baltic-Explorer. Key functionalities of the Baltic Explorer: • User-friendly map interface • Multi-device usability • Multi-user access model • Workspaces for group work • Up-to-date spatial maritime data from a large num-ber of providers • Create, edit and add vector features Use tests of the Baltic Explorer: 1. MSP workshop, Umeå, Sweden 2. PhD course, Turku, Finland 3. MSP workshop, Riga. Latvia 4. MSP course, University of Turku, Finland 5. MSP course, University of Gothenburg, Sweden 6. Denmark
  • Brauer, Anna; Mäkinen, Ville; Oksanen, Juha (Elsevier, 2021)
    Computers Environment and Urban Systems
    Mobile activity tracking data, i.e. data collected by mobile applications that enable activity tracking based on the use of the Global Navigation Satellite Systems (GNSS), contains information on cycling in urban areas at an un-precedented spatial and temporal extent and resolution. It can be a valuable source of information about the quality of bicycling in the city. Required is a notion of quality that is derivable from plain GNSS trajectories. In this article, we quantify urban cycling quality by esti-mating the fluency of cycling traffic using a large set of GNSS trajectories recorded with a mobile tracking appli-cation. Earlier studies have shown that cyclists prefer to travel continuously and without halting, i.e. fluently. Our method extracts trajectory properties that describe the stopping behaviour and dynamics of cyclists. It aggre-gates these properties to segments of a street network and combines them in a descriptive index. The suitability of the data to describe the cyclists' behaviour with street-level detail is evaluated by comparison with various data from independent sources. Our approach to characterizing cycling traffic fluency offers a novel view on the cyclability of a city that could be valuable for urban planners, application providers, and cyclists alike. We find clear indications for the data's ability to estimate characteristics of city cycling quality correctly, despite behaviour patterns of cyclists not caused by external circumstances and the data's inher-ent bias. The proposed quality measure is adaptable for different applications, e.g. as an infrastructure quality measure or as a routing criterion.
  • Häkli, Pasi; Koivula, Hannu (2020)
    Positio
  • Kettunen, Pyry; Koski, Christian; Rönneberg, Mikko; Oksanen, Juha (2020)
    Positio
  • Brauer, Anna; Mäkinen, Ville; Oksanen, Juha (2020)
    Proceedings of GISRUK
    Activity tracking data collected by mobile applications opens up a new, data-driven perspective on monitoring cycling in the city. In this work, we demonstrate how a large set of trajectories can be used to measure the cyclability of an urban infrastructure. We achieve this by defining the cycling traffic fuency index that describes the smoothness of cycling traffic on segments of a street network. Bias, uncertainty, and the divergence of infrastructure popularity presents challenges to the method, but within these limits, the index could be applied in city planning or as a routing criterion.
  • Kaasalainen, Sanna (CRC Press, 2020)
    The development of multispectral terrestrial laser scan-ning (TLS) is still at the very beginning, with only four instruments worldwide providing simultaneous three-dimensional (3D) point cloud and spectral measurement. Research on multiwavelength laser returns has been carried out by more groups, but there are still only about ten research instruments published and no commercial availability. This chapter summarizes the experiences from all these studies to provide an overview of the state of the art and future developments needed to bring the multispectral TLS technology into the next level. Alt-hough the current number of applications is sparse, they already show that multispectral lidar technology has po-tential to disrupt many fields of science and industry due to its robustness and the level of detail available.
  • Andrei, Constantin-Octavian; Johansson, Jan; Koivula, Hannu; Poutanen, Markku (IEEE, 2020)
    Proceedings of the International Conference on Localization and GNSS
    On 12 February 2020, the latest four Galileo satellites had completed one full year of space operational service. The satellites were launched on 25 July 2018. The quartet increased the operational capacity of the Galileo constellation to 22 satellites. This study reports on three signal-in-space (SiS) performance indicators - status, availability, and ranging accuracy - from 11 February 2019 to 12 February 2020. In addition, the study looks also at how the on-board satellite clocks have performed. The data analysis shows 100% data validity and signal health status for three our of the four satellites, whereas NAPA (No Accuracy Prediction Available) events accounted for about 2% of the time. In addition, SiS availability was higher than 95% in the first operational year. Furthermore, the 95th percentile of the global average of the instantaneous signal in space error is found to vary between 0.17 to 0.33 m on monthly basis. Lastly, the precise satellite clock biases show high short-term performance with 0.1 ps/s (10-13 s/s) standard deviations during the first operational year. The numerical results indicate a robust performance and high reliability for the youngest Galileo satellites in the constellation. They increase the number of operational satellites in the constellation and thus contribute to the Galileo’s increased popularity in the satellite-based positioning and navigation user community.
  • Ghobadi, Hossein; Spogli, Luca; Alfonsi, Lucilla; Cesaroni, Claudio; Cicone, Antonio; Linty, Nicola; Romano, Vincenzo; Cafaro, Massimo (Springer, 2020)
    GPS Solutions
    We contribute to the debate on the identification of phase scintillation induced by the ionosphere on the global navigation satellite system (GNSS) by introducing a phase detrending method able to provide realistic values of the phase scintillation index at high latitude. It is based on the fast iterative filtering signal decomposition technique, which is a recently developed fast implementation of the well-established adaptive local iterative filtering algorithm. FIF has been conceived to decompose nonstationary signals efficiently and provide a discrete set of oscillating functions, each of them having its frequency. It overcomes most of the problems that arise when using traditional time–frequency analysis techniques and relies on a consolidated mathematical basis since its a priori convergence and stability have been proved. By relying on the capability of FIF to efficiently identify the frequencies embedded in the GNSS raw phase, we define a method based on the FIF-derived spectral features to identify the proper cutoff frequency for phase detrending. To test such a method, we analyze the data acquired from GPS and Galileo signals over Antarctica during the September 2017 storm by the ionospheric scintillation monitor receiver (ISMR) located in Concordia Station (75.10° S, 123.33° E). Different cases of diffraction and refraction effects are provided, showing the capability of the method in deriving a more accurate determination of the σϕ index. We found values of cutoff frequency in the range of 0.73–0.83 Hz, providing further evidence of the inadequacy of the choice of 0.1 Hz, which is often used when dealing with ionospheric scintillation monitoring at high latitudes.
  • Vilppola, Maria (2020)
    Positio
  • Luokkala, Pekka (2020)
    Positio
  • Vilppola, Maria (2020)
    Positio
  • Kivekäs, Riikka (2020)
    Positio
  • Kivekäs, Riikka (2020)
    Positio
  • Vallet Garcia, José M. (MDPI, 2020)
    Journal of Sensor and Actuator Networks
    Using the classical received signal strength (RSS)-distance log-normal model in wireless sensor network (WSN) applications poses a series of characteristic challenges derived from (a) the model’s structural limitations when it comes to explaining real observations, (b) the inherent hardware (HW) variability typically encountered in the low-cost nodes of WSNs, and (c) the inhomogeneity of the deployment environment. The main goal of this article is to better characterize how these factors impact the model parameters, an issue that has received little attention in the literature. For that matter, I qualitatively elaborate on their effects and interplay, and present the results of two quantitative empirical studies showing how much the parameters can vary depending on (a) the nodes used in the model identification and their position in the environment, and (b) the antenna directionality. I further show that the path loss exponent and the reference power can be highly correlated. In view of all this, I argue that real WSN deployments are better represented by random model parameters jointly accounting for HW and local environmental characteristics, rather than by deterministic independent ones. I further argue that taking this variability into account results in more realistic models and plausible results derived from their usage. The article contains example values of the mean and standard deviation of the model parameters, and of the correlation between the path loss exponent and the reference power. These can be used as a guideline in other studies. Given the sensitivity of localization algorithms to the proper model selection and identification demonstrated in the literature, the structural limitations of the log-normal model, the variability of its parameters and their interrelation are all relevant aspects that practitioners need to be aware of when devising optimal localization algorithms for real WSNs that rely on this popular model.
  • Savola, Sakeri (2020)
    Positio
  • Vilppola, Maria (2020)
    Positio