Maanmittauslaitos: Recent submissions

Now showing items 1-20 of 374
  • Leppälä, Laura; Honkala, Salomon; Ferrara, Giorgia; Kirkko-Jaakkola, Martti; Kuusniemi, Heidi; Miettinen-Bellevergue, Seija (IEEE, 2019)
    European Navigation Conference (ENC)
    This paper underlines the challenges of navigation in the Arctic from the user perspective by means of an online survey. The main target of the survey was to find out the users' views and real-life experiences on the challenges in navigation and geospatial information-based services in the Arctic region. The paper studies relations between the represented industry, encountered challenges and areas of operation. Navigation in the Arctic area and similar circumstances in high latitudes is known to be challenging in terms of weather conditions, lack of services and infrastructure. As the novel technologies, e.g., intelligent transport systems mature, the need for exact and timely geospatial information will increase. According to the results, the most significant challenges are uneven coverage of positioning, untimely weather information, and telecommunication issues. Although the number of respondents was lower than expected (83 complete responses), the results indicate the differences in navigation and location-based services between countries and public versus commercial actors. We found two major dependent variables (nationality and market segment), which are analyzed further. The results suggest guidelines for the future developments of the navigation and positioning services in the high latitudes.
  • Latvala, Pekka; Lehto, Lassi; Kytö, Samuli (Stichting AGILE, 2019)
    Cascading download services combine various background services together so that their contents can be queried via a single service. A common problem with cascading services in a multinational setting is that the features coming from the services of different countries often do not match across border areas. Usually, edge-matching is executed iteratively as an off-line process between the neighbouring countries where adjustments and tests can be made during the matching process. On-the-fly edge-matching process is carried out during the service request and it leaves no room for modifications or negotiations. We present in this paper a method for performing on-the-fly edge-matching for linear features in a multinational cascading service environment. The proposed algorithm uses a country boundary lines data set and a connecting feature points data set that contains pre-determined locations on the boundary lines where the features should be matched. The results show that the proposed approach is suitable for most edge-matching situations where the connecting feature points are available. Problematic cases include situations, where the features are alternating across the border and cases where the features don’t reach near enough to the border line. In the proposed approach, the edge-matching is executed simply by moving selected line end points to the locations of connecting feature points. In future, the process could be improved by adopting conflation methods that produce visually smoother results and extending the edge-matching functionality to cover also polygonal features.
  • Mäkinen, Ville; Oksanen, Juha; Sarjakoski, Tapani (Stichting AGILE, 2019)
    The digital elevation model (DEM) is an invaluable product in numerous geospatial applications from orthorectification of aerial photographs to hydrological modelling and advanced 3D visualisation. With the current aerial laser scanning methods, superior quality digital elevation models can be produced over land areas, but surfaces over water bodies are visually problematic, especially for streams in 3D. We present a method to generate smooth, monotonically decreasing elevation surfaces over water bodies in DEMs. The method requires the point cloud data and the polygons delineating the water bodies as input data. We show how DEM visualisations improve by applying the presented method.
  • Linty, Nicola; Dovis, Fabio (MDPI, 2019)
    Applied Sciences
    The quality of positioning services based on Global Navigation Satellite Systems (GNSS) is improving at a fast pace, driven by the strict requirements of a plethora of new applications on accuracy, precision and reliability of the services. Nevertheless, ionospheric errors still bound the achievable performance and better mitigation techniques must be devised. In particular, the harmful effect due to non-uniform distribution of the electron density that causes amplitude and phase variation of the GNSS signal, usually named as scintillation effects. For many high-accuracy applications, this is a threat to accuracy and reliability, and the presence of scintillation effect needs to be constantly monitored. To this purpose, traditional receivers employ closed-loop tracking architectures. In this paper, we investigate an alternative architecture and a related metric based on the statistical processing of the received signal, after a code-wipe off and a noise reduction phase. The new metric is based on the analysis of the statistical features of the conditioned signal, and it brings the same information of the S4 index, normally estimated by means of closed-loop receivers. This new metric can be obtained at a higher rate as well as in the case of strong scintillations when a closed-loop receiver would fail the tracking of the GNSS signals.
  • Bhuiyan, M. Zahidul. H.; Ferrara, Nunzia Giorgia; Thombre, Sarang; Hashemi, Amin; Pattinson, M.; Dumville, M.; Alexandersson, M.; Axell, E.; Eliardsson, P.; Pölöskey, M.; Manikundalam, V.; Lee, S.; Reyes Gonzalez, J. (European Microwave Association, 2019)
    Proceedings of European Microwave Conference in Central Europe
    The H2020 project STRIKE3 contributes enormously for lifting EU industry and institutions to the premier position in the global market for GNSS interference monitoring, detection, reporting, receiver standardization, applica-tions and services. This has been achieved over the last three years through the deployment and operation of an international GNSS interference monitoring network to capture the scale and state of the problem, and through work with international GNSS partners to develop, nego-tiate, promote and implement standards for GNSS threat reporting and GNSS receiver testing. The achievements of STRIKE3 are based on the following cornerstones: i. STRIKE3 global interference monitoring network, ii. A draft interference reporting standard, iii. A draft receiver testing standard against interference, and iv. Internation-al knowledge sharing and awareness building against interference among key GNSS stakeholders across pub-lic and private sectors. All these aspects will be present-ed herein with greater details.
  • Lehto, Lassi; Kähkönen, Jaakko; Oksanen, Juha; Sarjakoski, Tapani (IARIA, 2019)
    International Conference on Advanced Geographic Information Systems, Applications, and Services
    A viable approach for tackling the challenges of integration and analysis of geospatial raster data is to pre-process datasets into a common framework and store them into a cloud repository, accessible through a set of well-defined access protocols. This paper describes an initiative called GeoCubes Finland, where the aim is to provide a number of country-wide raster geodatasets in a common schema. In addition to more traditional access methods, a custom Application Programming Interface (API) has been designed for supporting the various tasks related to retrieval, use, visualisation and analysis of the contained raster datasets.
  • Thombre, Sarang; Marila, Simo; Kirkko-Jaakkola, Martti; Honkala, Salomon; Koivisto, Michelle; Koivula, Hannu; Bhuiyan, M. Zahidul. H.; Petovello, Mark (Inside GNSS Media & Research LLC., 2019)
    Inside GNSS
    This article describes how a European Space Agency-supported research project called the Arctic-PNT Innovation Platform is investigating navigation accuracy and availability of signal and correction data using a specially equipped road segment in northern Finland and Norway.
  • Kettunen, Pyry; Oksanen, Juha (Taylor & Francis, 2019)
    Cartography and Geographic Information Science
    Animations have become a frequently utilized illustration technique on maps but changes in their graphical loading remain understudied in empirical geovisualization and cartographic research. Animated streamlets have gained attention as an illustrative animation technique and have become popular on widely viewed maps. We conducted an experiment to investigate how altering four major animation parameters of animated streamlets affects people’s reading performance of field maxima on vector fields. The study involved 73 participants who performed reaction-time tasks on pointing maxima on vector field stimuli. Reaction times and correctness of answers changed surprisingly little between visually different animations, with only a few occasional statistical significances. The results suggest that motion of animated streamlets is such a strong visual cue that altering graphical parameters makes only little difference when searching for the maxima. This leads to the conclusion that, for this kind of a task, animated streamlets on maps can be designed relatively freely in graphical terms and their style fitted to other contents of the map. In the broader visual and geovisual analytics context, the results can lead to more generally hypothesizing that graphical loading of animations with continuous motion flux could be altered without severely affecting their communicative power.
  • Puttonen, Eetu; Lehtomäki, Matti; Litkey, Paula; Näsi, Roope; Feng, Ziyi; Liang, Xinlian; Wittke, Samantha; Pandzic, Milos; Hakala, Teemu; Karjalainen, Mika; Pfeifer, Norbert (Frontiers Reseach Foundation, 2019)
    Frontiers in Plant Science
    Terrestrial Laser Scanning (TLS) can be used to monitor plant dynamics with a frequency of several times per hour and with sub-centimeter accuracy, regardless of external lighting conditions. TLS point cloud time series measured at short intervals produce large quantities of data requiring fast processing techniques. These must be robust to the noise inherent in point clouds. This study presents a general framework for monitoring circadian rhythm in plant movements from TLS time series. Framework performance was evaluated using TLS time series collected from two Norway maples (Acer platanoides) and a control target, a lamppost. The results showed that the processing framework presented can capture a plant's circadian rhythm in crown and branches down to a spatial resolution of 1 cm. The largest movements in both Norway maples were observed before sunrise and at their crowns' outer edges. The individual cluster movements were up to 0.17 m (99th percentile) for the taller Norway maple and up to 0.11 m (99th percentile) for the smaller tree from their initial positions before sunset.
  • Peltonen-Sainio, Pirjo; Jauhiainen, Lauri; Honkavaara, Eija; Wittke, Samantha; Karjalainen, Mika; Puttonen, Eetu (Frontiers Reseach Foundation, 2019)
    Frontiers in Plant Science
    Monocultural land use challenges sustainability of agriculture. Pre-crop value indicates the benefits of a previous crop for a subsequent crop in crop sequencing and facilitates diversifi-cation of agricultural systems. Traditional field experiments are resource intensive and evaluate pre-crop values only for a limited number of previous and subsequent crops. We deve-loped a dynamic method based on Sentinel-2 derived Norma-lized Difference Vegetation Index (NDVI) values to estimate pre-crop values on a field parcel scale. The NDVI-values were compared to the region specific 90th percentile of each crop and year and thereby, an NDVI-gap was determined. The NDVI-gaps for each subsequent crop in the case of mo-nocultural crop sequencing were compared to that for other previous crops in rotation and thereby, pre-crop values for a high number of previous and subsequent crop combinations were estimated. The pre-crop values ranged from +16% to -16%. Especially grain legumes and rapeseed were valuable as pre-crops, which is well in line with results from field expe-riments. Such data on pre-crop values can be updated and expanded every year. For the first time, a high number of previous and following crop combinations, originating from farmer’s fields, is available to support diversification of cur-rently monocultural crop sequencing patterns in agriculture.
  • Bhuiyan, Mohammad Zahidul H.; Ferrara, Nunzia Giorgia; Hashemi, Amin; Thombre, Sarang; Pattinson, Michael; Dumville, Mark (MDPI, 2019)
    GNSS-based applications are susceptible to different threats, including radio frequency interference. Ensuring that the new applications can be validated against the latest threats supports the wider adoption and success of GNSS in higher value markets. Therefore, the availability of standardized GNSS receiver testing procedures is central to developing the next generation of receiver technologies. The EU Horizon2020 research project STRIKE3 (Standardization of GNSS Threat reporting and Receiver testing through International Knowledge Exchange, Experimentation and Exploitation) proposed standardized test procedures to validate different categories of receivers against real-world interferences, detected at different monitoring sites. This paper describes the recorded interference signatures, their use in standardized test procedures, and analyzes the result for two categories of receivers, namely mass-market and professional grade. The result analysis in terms of well-defined receiver key performance indicators showed that performance of both receiver categories was degraded by the selected interference threats, although there was considerable difference in degree and nature of their impact.
  • Olsson, Per-Anders; Breili, Kristian; Ophaug, Vegard; Steffen, Holger; Bilker-Koivula, Mirjam; Nielsen, Emil; Oja, Tõnis; Timmen, Ludger (Oxford University Press, 2019)
    Geophysical Journal International
    For the first time, we present a complete, processed compilation of all repeated absolute gravity (AG) observations in the Fennoscandian postglacial land uplift area and assess their ability to accurately describe the secular gravity change, induced by Glacial Isostatic Adjustment (GIA). The dataset spans over more than three decades and consists of 688 separate observations at 59 stations. Ten different organisations have contributed with measurements using 14 different instruments. The work was coordinated by the Nordic Geodetic Commisson (NKG). Representatives from each country collected and processed data from their country, respectively, and all data were then merged to one dataset. Instrumental biases are considered and presented in terms of results from international comparisons of absolute gravimeters. From this dataset, gravity rates of change (g_dot) are estimated for all stations with more than two observations and a timespan larger than two years. The observed rates are compared to predicted rates from a global GIA model as well as the state of the art semi-empirical land uplift model for Fennoscandia, NKG2016LU. Linear relations between observed g_dot and the land uplift, h_dot (NKG2016LU), are estimated from the absolute gravity observations by means of weighted least squares adjustment (WLSA) as well as weighted orthogonal distance regression (WODR). The empirical relations are not significantly different from the modelled, geophysical relation g_dot = 0:03 - 0:163(+-0.016)h_dot. We also present a g_dot -model for the whole Fennoscandian land uplift region. At many stations, the observational estimates of g_dot still suffer from few observations and/or unmodelled environmental effects (e.g. local hydrology). We therefore argue that, at present, the best predictions of GIA-induced gravity rate of change in Fennoscandia are achieved by means of the NKG2016LU land uplift model, together with the geophysical relation between g_dot and h_dot.
  • Koistinen, Kai (2019)
    Positio - paikkatiedon erikoislehti
  • Lundvall, Anniina (2019)
    Positio - paikkatiedon erikoislehti
  • Oksanen, Juha; Puranen, Laura (2019)
    Positio - paikkatiedon erikoislehti
  • Karila, Kirsi; Matikainen, Leena; Litkey, Paula; Hyyppä, Juha; Puttonen, Eetu (Taylor & Francis, 2018)
    International Journal of Remote Sensing
    Multispectral airborne laser scanning (MS-ALS) sensors are a new promising source of data for auto-mated mapping methods. Finding an optimal time for data acquisition is important in all mapping applica-tions based on remotely sensed datasets. In this study, three MS-ALS datasets acquired at different times of the growing season were compared for automated land cover mapping and road detection in a suburban area. In addition, changes in the intensity were studied. An object-based random forest classi-fication was carried out using reference points. The overall accuracy of the land cover classification was 93.9% (May dataset), 96.4% (June) and 95.9% (August). The use of the May dataset acquired under leafless conditions resulted in more complete roads than the other datasets acquired when trees were in leaf. It was concluded that all datasets used in the study are applicable for suburban land cover map-ping, however small differences in accuracies between land cover classes exist.
  • Isomäki, Harri (Maanmittauslaitos, 2019)
    Maanmittauslaitoksen julkaisuja