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Prof. Juha Oksanen
Department of Geoinformatics and Cartography, Finnish Geospatial Research Institute in the National Land Survey of Finland, Geodeetinrinne 2, FI-02430 Masala, Finland

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0 DEM
0 DTM
0 Geovisual Analytics
0 Spatial data infrastructures
0 High-performance geocomputing

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DEM
Geovisual Analytics
Uncertainty-aware geospatial analysis

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Journal article
Published: 07 November 2020 in Applied Computing and Geosciences
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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.

ACS Style

Viljami Perheentupa; Ville Mäkinen; Hando-Laur Habicht; Juha Oksanen. Animated visualization of post-glacial land uplift and shore displacement from modeled paleotopographic reconstructions. Applied Computing and Geosciences 2020, 8, 100042 .

AMA Style

Viljami Perheentupa, Ville Mäkinen, Hando-Laur Habicht, Juha Oksanen. Animated visualization of post-glacial land uplift and shore displacement from modeled paleotopographic reconstructions. Applied Computing and Geosciences. 2020; 8 ():100042.

Chicago/Turabian Style

Viljami Perheentupa; Ville Mäkinen; Hando-Laur Habicht; Juha Oksanen. 2020. "Animated visualization of post-glacial land uplift and shore displacement from modeled paleotopographic reconstructions." Applied Computing and Geosciences 8, no. : 100042.

Journal article
Published: 16 October 2020 in Computers, Environment and Urban Systems
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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 unprecedented 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 estimating the fluency of cycling traffic using a large set of GNSS trajectories recorded with a mobile tracking application. 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 aggregates 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 inherent bias. The proposed quality measure is adaptable for different applications, e.g. as an infrastructure quality measure or as a routing criterion.

ACS Style

Anna Brauer; Ville Mäkinen; Juha Oksanen. Characterizing cycling traffic fluency using big mobile activity tracking data. Computers, Environment and Urban Systems 2020, 85, 101553 .

AMA Style

Anna Brauer, Ville Mäkinen, Juha Oksanen. Characterizing cycling traffic fluency using big mobile activity tracking data. Computers, Environment and Urban Systems. 2020; 85 ():101553.

Chicago/Turabian Style

Anna Brauer; Ville Mäkinen; Juha Oksanen. 2020. "Characterizing cycling traffic fluency using big mobile activity tracking data." Computers, Environment and Urban Systems 85, no. : 101553.

Articles
Published: 10 January 2019 in Cartography and Geographic Information Science
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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.

ACS Style

Pyry Kettunen; Juha Oksanen. Motion of animated streamlets appears to surpass their graphical alterations in human visual detection of vector field maxima. Cartography and Geographic Information Science 2019, 46, 489 -501.

AMA Style

Pyry Kettunen, Juha Oksanen. Motion of animated streamlets appears to surpass their graphical alterations in human visual detection of vector field maxima. Cartography and Geographic Information Science. 2019; 46 (6):489-501.

Chicago/Turabian Style

Pyry Kettunen; Juha Oksanen. 2019. "Motion of animated streamlets appears to surpass their graphical alterations in human visual detection of vector field maxima." Cartography and Geographic Information Science 46, no. 6: 489-501.

Journal article
Published: 01 October 2018 in Computers & Geosciences
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ACS Style

Janne Kovanen; Juha Oksanen; Tapani Sarjakoski. Near real-time coastal flood inundation simulation with uncertainty analysis and GPU acceleration in a web environment. Computers & Geosciences 2018, 119, 39 -48.

AMA Style

Janne Kovanen, Juha Oksanen, Tapani Sarjakoski. Near real-time coastal flood inundation simulation with uncertainty analysis and GPU acceleration in a web environment. Computers & Geosciences. 2018; 119 ():39-48.

Chicago/Turabian Style

Janne Kovanen; Juha Oksanen; Tapani Sarjakoski. 2018. "Near real-time coastal flood inundation simulation with uncertainty analysis and GPU acceleration in a web environment." Computers & Geosciences 119, no. : 39-48.

Articles
Published: 22 March 2017 in International Journal of Cartography
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Due to digitalization and rapid development of collection techniques for elevation data, the emphasis of users' needs for elevation contours has moved from needs of accurate elevation assessment towards needs of perception of landforms. This article introduces a design approach that considers the changed need, and a solution for accordingly generating contours for topographic maps from digital elevation models (DEMs). The solution builds upon comprehensively modifying and blending complete DEMs in order to make the generation procedure understandable for the map readers and to facilitate the readers' reliable interpretation of contours throughout the depicted terrain. The core of the solution is blending lightly and strongly smoothed DEMs according to the Topographic Position Index (TPI) that measures local deviation from surrounding variations of elevations. The solution is built to continuously consider the requirements for different levels of smoothing in areas of uniformly varying and locally deviating relief. An initial case study for typical and challenging Finnish terrains is described and success of the solution is qualitatively evaluated based on the resulting contours. Eventually, limitations of the solution as well as further evaluation and refinement needs are outlined with an intention to prepare the presented contour generation procedure for production.

ACS Style

Pyry Kettunen; Christian Koski; Juha Oksanen. A design of contour generation for topographic maps with adaptive DEM smoothing. International Journal of Cartography 2017, 3, 19 -30.

AMA Style

Pyry Kettunen, Christian Koski, Juha Oksanen. A design of contour generation for topographic maps with adaptive DEM smoothing. International Journal of Cartography. 2017; 3 (1):19-30.

Chicago/Turabian Style

Pyry Kettunen; Christian Koski; Juha Oksanen. 2017. "A design of contour generation for topographic maps with adaptive DEM smoothing." International Journal of Cartography 3, no. 1: 19-30.

Book chapter
Published: 13 October 2016 in Lecture Notes in Geoinformation and Cartography
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Sharing hyperlocal geospatial knowledge with one’s community may foster many positive outcomes, such as increasing a sense of community. However, much of this information travels by word of mouth and, therefore, does not reach everyone in time or even at all. We present the human-centred concept design process of #hylo, a geosocial network in which users can easily share personal, hyperlocal geospatial knowledge about their surroundings. Users may gain hyperlocal information of their own places, filtered with their own interests. We expect #hylo to increase (1) attachment to location, (2) interest in the area, and (3) social participation in local community. We explain the design process and show results from initial user studies that were encouraging, as the participants were interested in this kind of hyperlocal information and found it useful. Even those who are usually hesitant to post in social media, found this kind of community-focused, hyperlocal platform to be a pleasant place to share information.

ACS Style

Hanna-Marika Halkosaari; Mikko Rönneberg; Mari Laakso; Pyry Kettunen; Juha Oksanen; Tapani Sarjakoski. Concept Design of #hylo—Geosocial Network for Sharing Hyperlocal Information on a Map. Lecture Notes in Geoinformation and Cartography 2016, 309 -327.

AMA Style

Hanna-Marika Halkosaari, Mikko Rönneberg, Mari Laakso, Pyry Kettunen, Juha Oksanen, Tapani Sarjakoski. Concept Design of #hylo—Geosocial Network for Sharing Hyperlocal Information on a Map. Lecture Notes in Geoinformation and Cartography. 2016; ():309-327.

Chicago/Turabian Style

Hanna-Marika Halkosaari; Mikko Rönneberg; Mari Laakso; Pyry Kettunen; Juha Oksanen; Tapani Sarjakoski. 2016. "Concept Design of #hylo—Geosocial Network for Sharing Hyperlocal Information on a Map." Lecture Notes in Geoinformation and Cartography , no. : 309-327.

Journal article
Published: 16 September 2016 in IEEE Geoscience and Remote Sensing Magazine
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Processing high-resolution digital elevation models (DEMs) can be tedious due to the large size of the data. In uncertainty-aware drainage basin delineation, we apply a Monte Carlo (MC) simulation that further increases the processing demand by two to three orders of magnitude. Utilizing graphics processing units (GPUs) can speed up the programs, but their on-chip random access memory (RAM) limits the size of the DEMs that can be processed efficiently on one GPU. Here, we present a parallel uncertainty-aware drainage basin delineation algorithm and a multinode GPU compute unified device architecture (CUDA) implementation along with scalability benchmarking. All of the computations are run on the GPUs, and the parallel processes communicate using a message-passing interface (MPI) via the host central processing units (CPUs). The implementation can utilize any number of nodes, with one or many GPUs per node. The performance and scalability of the program have been tested with a 10-m DEM covering 390,905 km2, i.e., the entire area of Finland. Performing the drainage basin delineation for the DEM with different numbers of GPUs shows a nearly linear strong scalability.

ACS Style

Ville Mäkinen; Tapani Sarjakoski; Juha Oksanen; Jan Westerholm. A Multi-GPU Program for Uncertainty-Aware Drainage Basin Delineation: Scalability benchmarking with country-wide data sets. IEEE Geoscience and Remote Sensing Magazine 2016, 4, 59 -68.

AMA Style

Ville Mäkinen, Tapani Sarjakoski, Juha Oksanen, Jan Westerholm. A Multi-GPU Program for Uncertainty-Aware Drainage Basin Delineation: Scalability benchmarking with country-wide data sets. IEEE Geoscience and Remote Sensing Magazine. 2016; 4 (3):59-68.

Chicago/Turabian Style

Ville Mäkinen; Tapani Sarjakoski; Juha Oksanen; Jan Westerholm. 2016. "A Multi-GPU Program for Uncertainty-Aware Drainage Basin Delineation: Scalability benchmarking with country-wide data sets." IEEE Geoscience and Remote Sensing Magazine 4, no. 3: 59-68.

Journal article
Published: 10 March 2016 in Transactions in GIS
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This article investigates how workout trajectories from a mobile sports tracking application can be used to provide automatic route suggestions for bicyclists. We apply a Hidden Markov Model (HMM)-based method for matching cycling tracks to a “bicycle network” extracted from crowdsourced OpenStreetMap (OSM) data, and evaluate its effective differences in terms of optimal routing compared with a simple geometric point-to-curve method. OSM has quickly established itself as a popular resource for bicycle routing; however, its high-level of detail presents challenges for its applicability to popularity-based routing. We propose a solution where bikeways are prioritized in map-matching, achieving good performance; the HMM-based method matched correctly on average 94% of the route length. In addition, we show that the extremely biased nature of the trajectory dataset, which is typical of volunteered user-generated data, can be of high importance in terms of popularity-based routing. Most computed routes diverged depending on whether the number of users or number of tracks was used as an indicator of popularity, which may imply varying preferences among different types of cyclists. Revising the number of tracks by diversity of users to surmount local biases in the data had a more limited effect on routing.

ACS Style

Cecilia Bergman; Juha Oksanen. Conflation of OpenStreetMap and Mobile Sports Tracking Data for Automatic Bicycle Routing. Transactions in GIS 2016, 20, 848 -868.

AMA Style

Cecilia Bergman, Juha Oksanen. Conflation of OpenStreetMap and Mobile Sports Tracking Data for Automatic Bicycle Routing. Transactions in GIS. 2016; 20 (6):848-868.

Chicago/Turabian Style

Cecilia Bergman; Juha Oksanen. 2016. "Conflation of OpenStreetMap and Mobile Sports Tracking Data for Automatic Bicycle Routing." Transactions in GIS 20, no. 6: 848-868.

Journal article
Published: 01 October 2015 in Journal of Transport Geography
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Utilization of movement data from mobile sports tracking applications is affected by its inherent biases and sensitivity, which need to be understood when developing value-added services for, e.g., application users and city planners. We have developed a method for generating a privacy-preserving heat map with user diversity (ppDIV), in which the density of trajectories, as well as the diversity of users, is taken into account, thus preventing the bias effects caused by participation inequality. The method is applied to public cycling workouts and compared with privacy-preserving kernel density estimation (ppKDE) focusing only on the density of the recorded trajectories and privacy-preserving user count calculation (ppUCC), which is similar to the quadrat-count of individual application users. An awareness of privacy was introduced to all methods as a data pre-processing step following the principle of k-Anonymity. Calibration results for our heat maps using bicycle counting data gathered by the city of Helsinki are good (R2 > 0.7) and raise high expectations for utilizing heat maps in a city planning context. This is further supported by the diurnal distribution of the workouts indicating that, in addition to sports-oriented cyclists, many utilitarian cyclists are tracking their commutes. However, sports tracking data can only enrich official in-situ counts with its high spatio-temporal resolution and coverage, not replace them.

ACS Style

Juha Oksanen; Cecilia Bergman; Jani Sainio; Jan Westerholm. Methods for deriving and calibrating privacy-preserving heat maps from mobile sports tracking application data. Journal of Transport Geography 2015, 48, 135 -144.

AMA Style

Juha Oksanen, Cecilia Bergman, Jani Sainio, Jan Westerholm. Methods for deriving and calibrating privacy-preserving heat maps from mobile sports tracking application data. Journal of Transport Geography. 2015; 48 ():135-144.

Chicago/Turabian Style

Juha Oksanen; Cecilia Bergman; Jani Sainio; Jan Westerholm. 2015. "Methods for deriving and calibrating privacy-preserving heat maps from mobile sports tracking application data." Journal of Transport Geography 48, no. : 135-144.

Journal article
Published: 24 September 2015 in ISPRS International Journal of Geo-Information
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The breakthrough of GPS-equipped smartphones has enabled the collection of track data from human mobility on massive scales that can be used in route recommendation, urban planning and traffic management. In this work we present a fast map server that can generate and visualize heat maps of popular routes online from massive sports track data based on client preferences, e.g., running routes lasting less than an hour. The heat maps shown respect user privacy by not showing routes with less than a predefined number of different users, for instance five. The results are represented to the client using a dynamic tile layer. The current implementation uses data collected by the Sports Tracker mobile application with over 800,000 different tracks and 2.8 billion GPS data points. Stress tests indicate that the server can handle hundreds of simultaneous client requests in a single server configuration.

ACS Style

Jani Sainio; Jan Westerholm; Juha Oksanen. Generating Heat Maps of Popular Routes Online from Massive Mobile Sports Tracking Application Data in Milliseconds While Respecting Privacy. ISPRS International Journal of Geo-Information 2015, 4, 1813 -1826.

AMA Style

Jani Sainio, Jan Westerholm, Juha Oksanen. Generating Heat Maps of Popular Routes Online from Massive Mobile Sports Tracking Application Data in Milliseconds While Respecting Privacy. ISPRS International Journal of Geo-Information. 2015; 4 (4):1813-1826.

Chicago/Turabian Style

Jani Sainio; Jan Westerholm; Juha Oksanen. 2015. "Generating Heat Maps of Popular Routes Online from Massive Mobile Sports Tracking Application Data in Milliseconds While Respecting Privacy." ISPRS International Journal of Geo-Information 4, no. 4: 1813-1826.

Journal article
Published: 01 December 2014 in Computers & Geosciences
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ACS Style

David Eränen; Juha Oksanen; Jan Westerholm; Tapani Sarjakoski. A full graphics processing unit implementation of uncertainty-aware drainage basin delineation. Computers & Geosciences 2014, 73, 48 -60.

AMA Style

David Eränen, Juha Oksanen, Jan Westerholm, Tapani Sarjakoski. A full graphics processing unit implementation of uncertainty-aware drainage basin delineation. Computers & Geosciences. 2014; 73 ():48-60.

Chicago/Turabian Style

David Eränen; Juha Oksanen; Jan Westerholm; Tapani Sarjakoski. 2014. "A full graphics processing unit implementation of uncertainty-aware drainage basin delineation." Computers & Geosciences 73, no. : 48-60.

Journal article
Published: 01 September 2014 in Cartographica: The International Journal for Geographic Information and Geovisualization
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ACS Style

Juha Oksanen; Hanna-Marika Halkosaari; Tapani Sarjakoski; L. Tiina Sarjakoski. A User Study of Experimental Maps for Outdoor Activities. Cartographica: The International Journal for Geographic Information and Geovisualization 2014, 49, 188 -201.

AMA Style

Juha Oksanen, Hanna-Marika Halkosaari, Tapani Sarjakoski, L. Tiina Sarjakoski. A User Study of Experimental Maps for Outdoor Activities. Cartographica: The International Journal for Geographic Information and Geovisualization. 2014; 49 (3):188-201.

Chicago/Turabian Style

Juha Oksanen; Hanna-Marika Halkosaari; Tapani Sarjakoski; L. Tiina Sarjakoski. 2014. "A User Study of Experimental Maps for Outdoor Activities." Cartographica: The International Journal for Geographic Information and Geovisualization 49, no. 3: 188-201.

Articles
Published: 04 June 2013 in Cartography and Geographic Information Science
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The comparison of methods was carried out by setting up a user survey. The paper summarizes the answers to the questionnaire and analyzes and discusses some highlighting challenges.

ACS Style

Ulla Pyysalo; Juha Oksanen. Outlier highlighting for spatio-temporal data visualization. Cartography and Geographic Information Science 2013, 40, 165 -171.

AMA Style

Ulla Pyysalo, Juha Oksanen. Outlier highlighting for spatio-temporal data visualization. Cartography and Geographic Information Science. 2013; 40 (3):165-171.

Chicago/Turabian Style

Ulla Pyysalo; Juha Oksanen. 2013. "Outlier highlighting for spatio-temporal data visualization." Cartography and Geographic Information Science 40, no. 3: 165-171.

Journal article
Published: 01 February 2013 in The Cartographic Journal
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ACS Style

Friederike Schwarzbach; Juha Oksanen; L Tiina Sarjakoski; Tapani Sarjakoski. From LiDAR Data to Forest Representation on Multi-Scale Maps. The Cartographic Journal 2013, 50, 33 -42.

AMA Style

Friederike Schwarzbach, Juha Oksanen, L Tiina Sarjakoski, Tapani Sarjakoski. From LiDAR Data to Forest Representation on Multi-Scale Maps. The Cartographic Journal. 2013; 50 (1):33-42.

Chicago/Turabian Style

Friederike Schwarzbach; Juha Oksanen; L Tiina Sarjakoski; Tapani Sarjakoski. 2013. "From LiDAR Data to Forest Representation on Multi-Scale Maps." The Cartographic Journal 50, no. 1: 33-42.

Book chapter
Published: 20 October 2011 in Lecture Notes in Geoinformation and Cartography
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The paper describes the creation of a physical 3D model representing the Solvalla recreation area in South Finland. The data processing part includes the extraction of elevation models and other topographic features from LIDAR data and aerial photographs as well as steps to stack up the separate layers to the digital model suitable for the 3D printing. The present prototype is directed at the special needs of visually impaired persons. This influences the design of topographic objects such as roads and paths, the representation of certain areas such as water bodies and the choice of the colours in the model. The printed 3D model is used in a small user test with visually impaired persons.

ACS Style

Friederike Schwarzbach; Tapani Sarjakoski; Juha Oksanen; L. Tiina Sarjakoski; Suvi Weckman. Physical 3D models from LIDAR data as tactile maps for visually impaired persons. Lecture Notes in Geoinformation and Cartography 2011, 169 -183.

AMA Style

Friederike Schwarzbach, Tapani Sarjakoski, Juha Oksanen, L. Tiina Sarjakoski, Suvi Weckman. Physical 3D models from LIDAR data as tactile maps for visually impaired persons. Lecture Notes in Geoinformation and Cartography. 2011; ():169-183.

Chicago/Turabian Style

Friederike Schwarzbach; Tapani Sarjakoski; Juha Oksanen; L. Tiina Sarjakoski; Suvi Weckman. 2011. "Physical 3D models from LIDAR data as tactile maps for visually impaired persons." Lecture Notes in Geoinformation and Cartography , no. : 169-183.

Journal article
Published: 01 May 2011 in The Cartographic Journal
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ACS Style

Juha Oksanen; Friederike Schwarzbach; L Tiina Sarjakoski; Tapani Sarjakoski. Map Design for a Multi-Publishing Framework – Case MenoMaps in Nuuksio National Park. The Cartographic Journal 2011, 48, 116 -123.

AMA Style

Juha Oksanen, Friederike Schwarzbach, L Tiina Sarjakoski, Tapani Sarjakoski. Map Design for a Multi-Publishing Framework – Case MenoMaps in Nuuksio National Park. The Cartographic Journal. 2011; 48 (2):116-123.

Chicago/Turabian Style

Juha Oksanen; Friederike Schwarzbach; L Tiina Sarjakoski; Tapani Sarjakoski. 2011. "Map Design for a Multi-Publishing Framework – Case MenoMaps in Nuuksio National Park." The Cartographic Journal 48, no. 2: 116-123.

Book chapter
Published: 09 April 2011 in Lecture Notes in Geoinformation and Cartography
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The paper presents the usability evaluation of a map-based multipublishing service for outdoor leisure activities. The multi-publishing service allows users to access the same spatial information contents through different channels, such as printed maps, map applications for the web or mobile phones and other interactive media. These channels together form an interface for the geospatial information. The users may use the channel or the combination of channels that is best suited for the current situation. The user experience is constituted across the channels, thus the channels need to be networked and the seamless interaction between the channels needs to be ensured.

ACS Style

Hanna-Marika Flink; Juha Oksanen; Ulla Pyysalo; Mikko Rönneberg; L. Tiina Sarjakoski. Usability Evaluation of a Map-Based Multi-Publishing Service. Lecture Notes in Geoinformation and Cartography 2011, 239 -257.

AMA Style

Hanna-Marika Flink, Juha Oksanen, Ulla Pyysalo, Mikko Rönneberg, L. Tiina Sarjakoski. Usability Evaluation of a Map-Based Multi-Publishing Service. Lecture Notes in Geoinformation and Cartography. 2011; ():239-257.

Chicago/Turabian Style

Hanna-Marika Flink; Juha Oksanen; Ulla Pyysalo; Mikko Rönneberg; L. Tiina Sarjakoski. 2011. "Usability Evaluation of a Map-Based Multi-Publishing Service." Lecture Notes in Geoinformation and Cartography , no. : 239-257.

Journal article
Published: 17 November 2009 in GeoInformatica
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Delineation of drainage basins from a digital elevation model (DEM) has become a standard operation in a number of terrain analysis software packages, but limitations of the conventionally used techniques have become apparent. Firstly, the delineation methods make assumption of error-free data, which is an unreachable utopia even with modern sensor technology. Secondly, even though the computing capacity has increased dramatically during the last decades, sizes of geospatial data sets have increased simultaneously. Thus far, the typical problems arising when using uncertainty-aware geospatial analysis are 1) the computational complexity of the analysis and 2) memory allocation problems when large datasets are used. In this paper, we raise the question about the general need for developing scalable and uncertainty-aware algorithms for terrain analysis and propose improvements to the existing drainage basin calculation methods. The distributed uncertainty-aware catchment delineation methods with and without spatial partitioning of the DEM are introduced and the performance of the methods in different cases are compared.

ACS Style

Tomas Ukkonen; Juha Oksanen; Tapani Rousi; Tapani Sarjakoski. Comparison of distribution strategies in uncertainty-aware catchment delineation. GeoInformatica 2009, 15, 329 -349.

AMA Style

Tomas Ukkonen, Juha Oksanen, Tapani Rousi, Tapani Sarjakoski. Comparison of distribution strategies in uncertainty-aware catchment delineation. GeoInformatica. 2009; 15 (2):329-349.

Chicago/Turabian Style

Tomas Ukkonen; Juha Oksanen; Tapani Rousi; Tapani Sarjakoski. 2009. "Comparison of distribution strategies in uncertainty-aware catchment delineation." GeoInformatica 15, no. 2: 329-349.

Proceedings article
Published: 01 January 2007 in Proceedings of the 15th annual ACM international symposium on Advances in geographic information systems - GIS '07
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ACS Style

Tomas Ukkonen; Tapani Sarjakoski; Juha Oksanen. Distributed computation of drainage basin delineations from uncertain digital elevation models. Proceedings of the 15th annual ACM international symposium on Advances in geographic information systems - GIS '07 2007, 1 .

AMA Style

Tomas Ukkonen, Tapani Sarjakoski, Juha Oksanen. Distributed computation of drainage basin delineations from uncertain digital elevation models. Proceedings of the 15th annual ACM international symposium on Advances in geographic information systems - GIS '07. 2007; ():1.

Chicago/Turabian Style

Tomas Ukkonen; Tapani Sarjakoski; Juha Oksanen. 2007. "Distributed computation of drainage basin delineations from uncertain digital elevation models." Proceedings of the 15th annual ACM international symposium on Advances in geographic information systems - GIS '07 , no. : 1.

Research article
Published: 01 April 2006 in International Journal of Geographical Information Science
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The aim of our study was to characterize statistical and spatial details of the errors in a fine toposcale DEM derived by contour data. The fine toposcale DEMs are typically represented in a 5–50 m grid and used in the application scale 1:10 000–1:50 000. The errors were determined by using high‐quality reference data covering the entire study area from an airborne laser scanner. The work was motivated because of the essential role played by the correct characterization of DEM error in error‐propagation studies. The results showed that the spatial autocorrelation of the fine toposcale DEM error was the result of a complex combination of random and systematic‐like components, and its appropriate modelling by geostatistical methods is problematic because of the small extent of the areas in which the assumption of stationarity is valid. In addition, describing the shape of the DEM error distribution was impossible with a single parameter of dispersion. This was due to a large number of outliers, which suggests that more robust descriptors of the error should be used in addition to conventional error statistics.

ACS Style

J. Oksanen; T. Sarjakoski. Uncovering the statistical and spatial characteristics of fine toposcale DEM error. International Journal of Geographical Information Science 2006, 20, 345 -369.

AMA Style

J. Oksanen, T. Sarjakoski. Uncovering the statistical and spatial characteristics of fine toposcale DEM error. International Journal of Geographical Information Science. 2006; 20 (4):345-369.

Chicago/Turabian Style

J. Oksanen; T. Sarjakoski. 2006. "Uncovering the statistical and spatial characteristics of fine toposcale DEM error." International Journal of Geographical Information Science 20, no. 4: 345-369.