Maanmittauslaitos: Recent submissions

Now showing items 1-20 of 380
  • Visuri, Hanna; Jokela, Joonas; Mesterton, Nils; Latvala, Pekka; Aarnio, Timo (Copernicus Publications, 2019)
    The International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences
    The amount and the quality of 3D spatial data are growing constantly, but the data is collected and stored in a distributed fashion by various data collecting organizations. This may lead to problems regarding interoperability, usability and availability of the data. Traditionally, national spatial data infrastructures have focused on 2D data, but recently there has been great progress towards introducing also 3D spatial data in governmental services. This paper studies the process of creating a country-wide 3D data repository in Finland and visualizing it for the public by using an open source map application. The 3D spatial data is collected and stored into one national topographic database that provides information for the whole society. The data quality control process is executed with an automated data quality module as a part of the import process to the database. The 3D spatial data is served from the database for the visualization via 3D service and the visualization is piloted in the National Geoportal.
  • Matikainen, Leena; Pandzic, Milos; Li, Fashuai; Karila, Kirsi; Hyyppä, Juha; Litkey, Paula; Kukko, Antero; Lehtomäki, Matti; Karjalainen, Mika; Puttonen, Eetu (SPIE, 2019)
    Journal of Applied Remote Sensing
    The rapid development of remote sensing technologies pro-vides interesting possibilities for the further development of nationwide mapping procedures that are currently based mainly on passive aerial images. In particular, we assume that there is a large undiscovered potential in multitemporal airborne laser scanning (ALS) for topographic mapping. In this study, automated change detection from multitemporal multispectral ALS data was tested for the first time. The results showed that direct comparisons between height and intensity data from different dates reveal even small chang-es related to the development of a suburban area. A major challenge in future work is to link the changes with objects that are interesting in map production. In order to effectively utilize multisource remotely sensed data in mapping in the future, we also investigated the potential of satellite images and ground-based data to complement multispectral ALS. A method for continuous change monitoring from a time series of Sentinel-2 satellite images was developed and tested. Finally, a high-density point cloud was acquired with terres-trial mobile laser scanning and automatically classified into four classes. The results were compared with the ALS data, and the possible roles of the different data sources in a fu-ture map updating process were discussed.
  • Perheentupa, Viljami; Mäkinen, Ville; Oksanen, Juha (Copernicus Publications, 2019)
    The Abstracts of the International Cartographic Association
    Glacial isostatic adjustment (GIA) is an ongoing phenomenon that characterizes the landscape of the High Coast (63°04'N, 18°22'E, Sweden) / Kvarken archipelago (63°16'N, 21°10'E, Finland) UNESCO World Heritage site. GIA occurs as the Earth’s crust that was depressed by the continental ice sheet during the last glacial period is slowly rebounding towards isostatic equilibrium. The maximum rate of land uplift in the area is more than eight millimetres per year, which – along with the very different topographical reliefs of the opposite coasts – makes the region an excellent study area for land uplift as a phenomenon. As there is a marine area between the coasts, shore displacement is an essential part of the phenomenon in the study area. The cartographic representation of GIA and shore displacement has classically relied on static maps representing isobases of the uplift rates and of ancient shorelines. However, to dynamically visualize and communicate the continuity and the nature of the phenomena, an animated map is required. To create a visually balanced, seamless animation, we need to create high-resolution image frames that represent digital elevation models (DEMs) together with extracted shorelines of different moments of time. To create these frames, we developed a mathematical model to transform the DEM in a given time for the past ~9300 years. We used the most recent LiDAR-derived DEMs of Finland and Sweden, and a bathymetric model of the Gulf of Bothnia as our initial data, along with a land uplift rate surface derived from geophysical measurements. We compared the current uplift rates with the shoreline observations of the ancient Baltic Sea stages, Litorina Sea and Ancylus Lake, and created a linear model between the elevations of the shorelines and the present-day uplift rates, as there was a near-linear correlation in both cases. Based on the current uplift rates and the elevations and the dating of the ancient shorelines, we derived an exponential model to describe the non-linear correlation between the elapsed time and the occurred land uplift. Near the present time, we adapted the formula proposed by Ekman (2001) to make the model more robust closer to the present day. We assumed that although the uplift rate varies in time, the spatial relation of uplift rates remains the same. Furthermore, as the land uplift is an exponentially decelerating phenomenon occurring with a significantly lower annual rate than shortly after the de-glaciation (Eronen et al. 2001, Nordman et al. 2015), and with most of the total uplift already having occurred (Ekman 1991), we assumed a constant rate of uplift from the present day to the near geological future. We did not consider potential sea level changes caused by human-driven climate change in the predictions, as the geological time scale vastly exceeds the time range of the climate models. Neither did we take into account the historical transgression phases, as they did not appear dominating in the area. The elevation and bathymetry data were harmonized and resampled into 4K (3840 x 2160) pixel dimensions to utilize the best commercially available screen resolutions and to avoid unnecessary sub-pixel level computations. This resulted in a spatial pixel size of about 200 metres. The initial spatial resolution of the DEMs of Finland and Sweden was 2 metres and 1 metre, respectively, while the bathymetric data had a spatial pixel size of 400 metres. This, along with the fact that the bathymetric data was partly modelled and inaccurate near the coastlines, meant that it had to be oversampled to generate plausible coastal bathymetry and to allow any future estimations of shore displacement. All the datasets were resampled to EPSG:3857 Pseudo-Mercator projection to facilitate any future use in web map applications. As the visualized area is only about 430 kilometres in the north-south direction, the use of this projection did not introduce cartographic issues. The rendered frames required by the animation were produced with a programmatic conversion of raster files to RGBimages. The visualization of shore displacement was implemented by a discontinuity in elevation dependent colour scale at sea level. The bathymetry was visualized with a continuous colour scale in shades of blue until the elevation of zero metres. Elevations above zero were visualized with a colour scale starting from green to create an impression of a discrete shoreline (Figure 1). Figure 1. Examples of individual frames for the land uplift animation. Litorina stage 7300 BP (a), 3000 BP (b), current stage (c), and 1000 years after present (d). The imprecision of the predicted shoreline placement compared to the past reconstructions can be observed in the last frame. The whole process from computing the DEMs to rendering the frames was implemented in Python, without the need for traditional GUI operated GIS or image processing software. The raster data was read and processed with GDAL and NumPy libraries, and the visualization was carried out using Matplotlib and Python Imaging Library. Each DEM was given the same elevation based colour scale and an individually created hillshading that was blended with the image by multiplication. The whole process was carried out as an open source solution. The interval between the calculated frames was set to five years as, particularly at the Swedish coast, the shore displacement can appear abrupt with a longer time interval. The frame duration was set to 0.05 seconds, which means a 100-second duration for an animation of 10 000 years. The resulting DEM reconstructions show good agreement with comparable data, such as the Litorina reconstructions by the Geological Survey of Finland (GTK). Also, the mathematical model appears to be in line with previous reconstructions conducted in the area (e.g. Nordman et al. 2015). So far, any continuous series of paleogeographic DEM reconstructions comparable to ours has not been published for this area. The animation provides an understandable way of perceiving the continuous but decelerating nature of the land uplift phenomenon and also highlights the differences in the post-glacial history of Finnish and Swedish coasts. To further improve the visualization, we must consider the removal of post-glacially developed features in the present day DEM, e.g. the various rivers that can both cause bias in the shore displacement and uplift estimations and appear visually distractive. In the very early frames of the animation, the retracting ice sheet must also be present. Also, a balanced addition of other cartographic elements, such as present-day hydrography and place names, can further improve the overall presentation.
  • Hashemi, Amin; Thombre, Sarang; Ferrrara, N. Giorgia; Bhuiyan, M. Zahidul H.; Pattinson, Michael (IEEE, 2019)
    International Conference on Localization and GNSS (ICL-GNSS) 2019
  • Peltonen-Sainio, Pirjo; Jauhiainen, Lauri; Laurila, Heikki; Sorvali, Jaana; Honkavaara, Eija; Wittke, Samantha; Karjalainen, Mika; Puttonen, Eetu (Elsevier, 2019)
    Land Use Policy
    Recent studies assessing agricultural policies, including the EU’s Agri-Environment Scheme, have shown that these have been successful in attaining some environmental goals. In Finland, however, the economic situation of farms has dramatically fallen and hence, the actions do not result in social acceptability. Sustainable intensification is a means to combine the three dimensions of sustainability: environmental, economic and social. Here we introduce a novel land use optimization and planning tool for the sustainable intensification of high-latitude agricultural systems. The main rationale for the development of the tool was to achieve a systematic and comprehensive conception for land allocation across Finland, where field parcels vary substantially in their conditions. The developed tool has a three-step scoring system based on seven physical characteristics (parcel size, shape, slope, distance to the farm center and waterways, soil type and logistic advantages) and the productivity of field parcels. The productivity estimates are based on vegetation indices derived from optical satellite data. The tool allocates virtually all >1 million field parcels in Finland either to sustainable intensification, extensification or afforestation. The tool is dynamic in the sense that its boundary values for land allocation can be fixed according to changes in social targets and supporting policies. Additionally, it can be applied year after year by acknowledging new available data, e.g., on vegetation indices and field parcel rearrangements between farms. Furthermore, it can be applied to all farm types and across Finland. It is a tool for land use planning, implementation and monitoring, but its thorough implementation calls for further development of policy instruments, which are currently more supportive towards land sharing than land sparing activities.
  • 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)
    Sensors
    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.