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Browsing by study line "Geoinformatik"

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  • Lehtonen, Pyry (2021)
    Geographical accessibility to sports facilities plays an important role when choosing a sports facility. The aim of my thesis is to examine geographical accessibility for sports facilities in Helsinki and Jyväskylä. The data of my study consists of the facilities of three different types of sports in Helsinki, Jyväskylä. The chosen types of facilities are ball parks, disc golf courses and fitness centers. I also use demographic data that cover the age groups of 7-12, 20-24 and 60-64. Mapple Analytics Ltd has produced geographical accessibility data covering whole of Finland which I also use as my data. In my thesis I analyzed geographical accessibility of sports facilities and compare the results to demographic data. Both the geographical accessibility data and demographic data is in 250 x 250 m grid level. the methods I used were Local Moran’s I and Bivariate Local Moran’s I. I applied the methods so that I combined the travel-time data and demographic data. The travel-times are from Mapple Insights API. The travel modes I have used are cycling and driving because people travel to sports facilities mostly by driving or by active methods, especially cycling. The travel-times to ball parks and fitness centers are overall good in both study regions. The good geographical accessibility is caused by that the service pattern is so dense for ball parks and fitness centers. The service pattern covers almost all of the inhabited area in both study regions. However, for some postal areas seem to have not so good geographical accessibility to ball parks. In some areas in Helsinki the geographical accessibility to disc golf course can be considered to be somewhat bad. For the chosen age groups only 20-24-year-olds have unsatisfactory travel-times to disc golf course either by cycling or driving. Other age groups do not show a similar pattern because of the different service pattern of ball parks and fitness centers. Demographic variables do not explain the travel times in this context. It is important to see which postal areas have good or bad geographical accessibility to sports facilities. This helps the future planning of sports facilities. In the future it is also possible to apply non spatial methods to the data I have collected or a similar dataset. It would also be possible to which demographic variable best explains travel-times. Because of Mapple Insighs API data is in 250 x 250 m grid level many applications can be developed using the data.
  • Kukkavuori, Susanna (2024)
    Sub-arctic river ecosystems are recognized as biodiversity hotspots in the region. However, gaps exist in understanding the potential impacts of the current climate change on these sensitive environments due to a lack of local data and knowledge of suitable monitoring methods. Remote sensing offers a promising approach to map river bathymetry, a critical factor in monitoring river environments. In this study, I investigated the efficacy of three remote sensing methods – multibeam echo sounding, green-wavelength airborne laser scanning, and multispectral satellite imagery – for mapping bathymetry along the Tana River, located at the border of northern Finland and Norway. Multibeam echo sounding, and laser scanning offer high-resolution and good penetration capabilities for mapping shallow river bathymetry. Satellite imagery can cover large spatial areas, often more cost-effectively than other remote sensing methods, albeit with lower spatial resolution. The analysis involved processing field survey data from two study sites with varying topography, slope, and flow velocity. I conducted the bathymetric model generation by using Inverse Distance Weighting interpolation and Lyzenga algorithm methods. The validation was carried out through error assessment. Performance evaluation of the bathymetric models and their differences were conducted by calculating linear regression and Pearson’s correlation coefficient, vertical difference, and bottom roughness. The results suggest that all three remote sensing methods successfully captured the main characteristics of the river bottom shape, aligning with the geomorphological characteristics of the study sites. The multibeam echo sounding provided densest and most coherent bathymetric models (mean R2=0.57 and RMSE=0.80). The airborne laser scanning produced bathymetric models with highest uncertainty in elevation due to noise and gaps in the data and showed better accuracy above the water surface than below (mean R2=0.27 and RMSE=1.18, compared to R2=0.98 and RMSE=0.18). The comparability of the bathymetry derived from satellite imagery against other methods was not optimal due to notably lower spatial resolution, but the satellite-based bathymetric models were able to capture the general variations in river bottom elevation (mean R2=0.48 and RMSE=0.96). The study area that was shallower, had a slow flow rate, and had a sandy bottom yielded more accurate bathymetric models. This was evidenced by strong positive correlation coefficients (mean r=0.83, compared to r=0.23 in the other site) and fewer river bottom profile differences between the models. The findings highlight the importance of comprehensive validation data and proper data pre-processing. Addressing these challenges is important for advancing the understanding of how to map and monitor sub-arctic river bathymetry.
  • Redding, Alisa (2023)
    The sixth wave of mass species extinction currently threatens biodiversity and life on Earth as we know it. Conservationists seeking to protect threatened species are tasked with raising awareness and achieving funding for these protections, often by appealing to the public. In modern-day conservation research, digital data holds an increasingly important role in understanding conservation goals, messaging, and impacts. The media especially is a key player in disseminating information to the public about conservation. The data for this thesis was retrieved by an automated pipeline that collects Google News articles on species in Appendix I of the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES) (Di Minin & Kulkarni 2021). I used a descriptive approach to assess species information and popularity online, as well as the location and temporality of that information and popularity. I supplemented the dataset with metrics from Facebook to investigate article popularity, Google to investigate species popularity, and Wikipedia to investigate temporal trends in species interest. The quantitative results show an expected bias towards large, terrestrial mammals. Large cats are cited frequently across all data metrics. Popular headlines employ emotional or political language to attract readers. Frequently used words in titles of popular articles highlight diminishing populations, new or rare species, and certain species like whales, pangolins, rhinos, and turtles. The majority of the news organizations in the dataset are based in the United States. The United States is also most frequently mentioned in the text of the articles, though India and China lead with the highest number of species with native ranges in their countries. Wikipedia pageviews reveal the fluctuations in online species interest, and possible reasons are investigated through the article titles. The results reveal that charismatic, large mammals receive the highest attention in the media, and among the public. Results also showcase the potential of the pipeline and database for further development and addressing research gaps. Overall, the investigations in this thesis provide avenues to improve conservation messaging and address conservation biases.
  • Vuorinne, Ilja (2020)
    Biomass is an important parameter for crop monitoring and management, as well as for assessing carbon cycle. In the field, allometric models can be used for non-destructive biomass assessment, whereas remote sensing is a convenient method for upscaling the biomass estimations over large areas. This study assessed the dry leaf biomass of Agave sisalana (sisal), a perennial crop whose leaves are grown for fibre and biofuel production in tropical and subtropical regions. First, an allometric model was developed for predicting the leaf biomass. Then, Sentinel-2 multispectral satellite imagery was used to model the leaf biomass at 8851 ha plantation in South-Eastern Kenya. For the allometric model 38 leaves were sampled and measured. Plant height and leaf maximum diameter were combined into a volume approximation and the relation to biomass was formalised with linear regression. A strong log-log linear relation was found and leave-one-out cross-validation for the model showed good prediction accuracy (R2 = 0.96, RMSE = 7.69g). The model was used to predict biomass for 58 field plots, which constituted a sample for modelling the biomass with Sentinel-2 data. Generalised additive models were then used to explore how well biomass was explained by various spectral vegetation indices (VIs). The highest performance (D2 = 74%, RMSE = 4.96 Mg/ha) was achieved with VIs based on the red-edge (R740 and R783), near-infrared (R865) and green (R560) spectral bands. Highly heterogeneous growing conditions, mainly variation in the understory vegetation seemed to be the main factor limiting the model performance. The best performing VI (R740/R783) was used to predict the biomass at plantation level. The leaf biomass ranged from 0 to 45.1 Mg/ha, with mean at 9.9 Mg/ha. This research resulted a newly established allometric equation that can be used as an accurate tool for predicting the leaf biomass of sisal. Further research is required to account for other parts of the plant, such as the stem and the roots. The biomass-VI modelling results showed that multispectral data is suitable for assessing sisal leaf biomass over large areas, but the heterogeneity of the understory vegetation limits the model performance. Future research should address this by investigating the background effects of understory and by looking into complementary data sources. The carbon stored in the leaf biomass at the plantation corresponds to that in the woody aboveground biomass of natural bushlands in the area. Future research is needed on soil carbon sequestration and soil and plant carbon fluxes, to fully understand the carbon cycle at sisal plantation.
  • Aalto, Iris (2020)
    Global warming is expected to have detrimental consequences on fragile ecosystems in the tropics and to threaten both the global biodiversity as well as food security of millions of people. Forests have the potential to buffer the temperature changes, and the microclimatic conditions below tree canopies usually differ substantially from the ambient macroclimate. Trees cool down their surroundings through several biophysical mechanisms, and the cooling benefits occur also with trees outside forest. Remote sensing technologies offer new possibilities to study how tree cover affects temperatures both in local and regional scales. The aim of this study was to examine canopy cover’s effect on microclimate and land surface temperature (LST) in Taita Hills, Kenya. Temperatures recorded by 19 microclimate sensors under different canopy covers in the study area and LST estimated by Landsat 8 thermal infrared sensor (TIRS) were studied. The main interest was in daytime mean and maximum temperatures measured with the microclimate sensors in June-July 2019. The Landsat 8 imagery was obtained in July 4, 2019 and LST was retrieved using the single-channel method. The temperature records were combined with high-resolution airborne laser scanning (ALS) data of the area from years 2014 and 2015 to address how topographical factors and canopy cover affect temperatures in the area. Four multiple regression models were developed to study the joint impacts of topography and canopy cover on LST. The results showed a negative linear relationship between daytime mean and maximum temperatures and canopy cover percentage (R2 = 0.6–0.74). Any increase in canopy cover contributed to reducing temperatures at all microclimate measuring heights, the magnitude being the highest at soil surface level. The difference in mean temperatures between 0% and 100% canopy cover sites was 4.6–5.9 ˚C and in maximum temperatures 8.9–12.1 ˚C. LST was also affected negatively by canopy cover with a slope of 5.0 ˚C. It was found that canopy cover’s impact on LST depends on altitude and that a considerable dividing line existed at 1000 m a.s.l. as canopy cover’s effect in the highlands decreased to half compared to the lowlands. Based on the results it was concluded that trees have substantial effect on both microclimate and LST, but the effect is highly dependent on altitude. This indicates trees’ increasing significance in hot environments and highlights the importance of maintaining tree cover particularly in the lowland areas. Trees outside forests can increase climate change resilience in the area and the remaining forest fragments should be conserved to control the regional temperatures.
  • Hirvonen, Hanna (2022)
    The African savanna elephant (Loxodonta africana) as a renowned “ecosystem engineer” modifies its habitat by sometimes destroying woody vegetation. Their destructive effect intensifies during the dry seasons, when they form larger herds and seek to consume woody plants, especially near permanent water sources. If this happens season after season in a restricted area, such as a wildlife reserve, the tree cover is reduced. Since elephants tend to make smaller trees to fall more easily than the larger ones, this “elephant problem” harms the regeneration ability of the ecosystem in a long run, even turning savannas into grasslands. With less and less trees available, elephants and other fauna in conservation areas could end up being at a fatal risk. Multi-scale vegetation structure can be studied with airborne (ALS) and terrestrial laser scanning (TLS). Although both types of LiDAR have been applied in studies on trees, most of the ALS studies concern biomass and none of the TLS research cover elephants. Tree structure on the individual tree level can be modelled using TreeQSM modelling that has not yet been applied in savanna vegetation. This study can be considered pioneering as it attempts to provide answers to these two study questions: (1) How does tree density derived from airborne laser scanning data correlate with elephant density, elephant path proximity, and river proximity? (2) How do tree architecture metrics derived from terrestrial laser scanning data correlate with elephant path proximity and river proximity? The study area is Taita Hills Wildlife Sanctuary, a small privately-owned wildlife conservancy in southeastern Kenya that falls within an area scanned with ALS in 2014. The vegetation of the reserve has been changing for many decades, and the latest changes in the vegetation cover are visible from satellite images. The “elephant problem” near the area was scientifically discussed already in 1960’s, so their damage may have been taking place for a long time. There are two datasets from the area for estimating elephant occurrence (elephant density based on elephant observation points and elephant track proximity based on elephant tracks) and one for the proximity to the river. Tree density was calculated based on detected treetops from the ALS point cloud and its correlations between the elephant predictors and the river proximity was analyzed. TLS measurements of 72 individual trees of Vachellia tortilis and Newtonia hildebrandtii were made in January and February 2020 in Taita Hills Wildlife Sanctuary. 53 were successfully modelled with TreeQSM. The correlations between the tree structure metrics and elephant density, elephant track proximity, and the river proximity were analyzed. The values for crown ratio, the metric that correlated significantly with the elephant track proximity were predicted to assess the meaning of the results in practice. The overall findings from both analyses (ALS and TLS) may suggest that trees in Taita Hills Wildlife Sanctuary may have suffered from elephant damage, since lower tree density correlates with both the elephant density estimates and the elephant track proximity. The trees scanned with TLS seem to be somewhat larger in closer proximities to the elephant tracks, while smaller trees are more able to survive in areas further away. Quantifying elephant damage in more detail, such as torn or hanging branches, was still not achieved by this study. Regardless, it can be concluded that there is enough foundation for further research on the important issue, the phenomenon that can turn dangerous to many species that were supposed to be protected.
  • Becker, Eemil (2024)
    Tree microhabitats are important in assessing forest biodiversity and ecological value. Knowledge of what types of forests and trees bear the most microhabitats can be useful in sustainable forest management and conservation. Based on research that has been done on assessing the main drivers of microhabitats, tree age, size and developmental stage have been established as the main driving factors for microhabitats. Terrestrial laser scanning data has been used in microhabitat modelling, either at forest stand scale, or by directly detecting certain microhabitats from the data using machine learning. However, high precision individual tree level architectural data facilitated by terrestrial laser scanning and quantitative structure modelling has not yet been tested in microhabitat related research. In this thesis I use the detailed tree-level information that the quantitative structure models provide to determine whether high precision tree architectural data improves the modelling performance of tree microhabitats. Terrestrial laser scanning data was collected from ten plots in a hardwood riparian forest area near Leipzig, Germany. Two tree microhabitat inventories from these ten plots collected in the winter of 2020-2021 and January 2023 respectively as reference data sets. Running increasingly complex models for predicting microhabitat richness for the two datasets I found that 1) While the performance gets better with addition of more tree structural variables, the difference was not substantial between models using only variables attainable by less labour-intensive methods and models with more complex, TLS-derived variables. 2) Comparing the performance metrics between the two datasets showed that the models performed very differently between the inventories, suggesting that microhabitat inventory data collection is susceptible to subjectivity, and the surveys are prone to having observer biases. These discrepancies between the datasets further reinforce the established consensus that tree microhabitats are hard to detect. Difficulties with creating reliable reference data sets, along with the inherently random nature of tree microhabitat occurrence can make microhabitat modelling difficult. This thesis concludes that high precision tree structural data might not increase the microhabitat prediction power in a way that justifies the cost. The results support the established consensus that microhabitat occurrence is mainly driven by tree size and living status. Variables such as species, tree neighbourhood metrics and stand level metrics were not included in this study, but should be researched more, as for example, tree structural characteristics and compartmentalization capacity vary between tree species. Additionally, based on the findings in this thesis, further effort into the standardisation of microhabitat inventories and their collection should be done. There should be little to no room for interpretation regarding the typologies of microhabitats and their related field work methodologies, leading to less observer biases and more comparable and comprehensive data.
  • Ehnström, Emil Mattias (2021)
    The number of people belonging to a language minority in Finland is increasing and people are becoming more and more spatially mobile. This has also led to an increase in transnationals and higher rates of cross-border mobility. With new methods involving social media big data, we can map spatial mobility patterns in new ways and deepen the understanding of how people relate to space. Differences in spatial mobility can for example give us an indication of the rate of integration into society. Some claim that a more spatially mobile life is a sign of success, but can we see differences in spatial mobility between people in Finland? The three language minorities considered in this thesis are Swedish, Russian, and Estonian. The history and culture of these groups are different as well as their status in Finnish society. Swedish speakers, with a national language status, have a different role in society, but do this well integrated minority differ from the other ones spatially? By using Twitter data and looking at the spatial mobility within Finland, we see where differences occur between language groups. To understand how strong ties the language groups have with neighbouring countries, we look at cross-border mobility to Estonia, Russia, and Sweden. The results show that there are differences in the spatial mobility of language minorities in Finland. Estonian speakers most frequently visit Estonia, while at the same time they are less mobile within Finland. The variation was large for Russian speakers, with some visiting Russia often and others almost never. Swedish speakers seem to have relatively weak ties to Sweden, compared to the other language groups and have very similar spatial mobility to the majority Finnish speaking population.
  • Haapanen, Eemil (2024)
    Cartographic interaction, the dialogue between a human and a map, is a process enabling indispensable ways of reasoning with spatial information. Interactive maps are digital applications, increasingly often made with web technologies. Studying and crafting cartographic interaction calls for user-inclusive studies designed around interactive map use, also necessitating the assessment of the rapidly evolving technologies enabling interactive maps. This study combines the technology- and user-centric aspects of cartographic interaction. I ask what the performance bottlenecks of a web map application are, and how different web mapping libraries compare as a platform for real-time cartographic interaction. I also ask how users interact with a highly interactive map interface, and whether cartographic interaction changes the way they perceive the mapped phenomenon. Developing a web map application, a map interface to a massive dataset on spatial accessibility (the Helsinki region Travel Time Matrix), is central to this study. I answer my technology-centric questions by assessing the technological aspects of interactive maps through the development process. To answer my user-centric questions, I carry out a user survey (n=31) by combining the web map application with an online questionnaire. My results show that the geometrical complexity of data, i.e. the number and detail of geometries to render, was the main factor limiting map responsiveness. Notable differences between web mapping libraries existed in the context of dynamic real-time interaction. Survey participants preferred to use the most dynamic mode of map interaction, and perceived the mapped phenomenon differently depending on how they interacted with the map. These results illustrate the dependence between map interface capabilities and technological design choices such as data simplification and software selection. The results also support the wider call for more dynamic map interfaces, indicating that real-time cartographic interaction can be a functional approach to exploring complex data. As a whole, the results highlight the need for the ongoing study of both mapping technologies and map use in order to discover and utilize the potential of cartographic interaction.
  • Lämsä, Suvi (2021)
    Urban environments are constantly changing and expanding. They grow, evolve, and adapt to society and residents’ needs. Environmental changes have an impact also on urban green such as trees. This is because the increase of building stock and expanding cityscape will target these green spaces. However, the significance of those green spaces is understood as they have a positive impact on the residents’ well-being and health. For example, urban trees are known to improve the air quality and to provide mentally relaxing environments for residents. As this importance is emphasized, changes in the areas must be monitored, which increases the importance of the change detection studies. Change detection is a comparison of two or more datasets from the same area but at different times. Principally, changes have been detected with various remote sensing methods, such as aerial- and satellite images, but as airborne laser scanning technology and multi-temporal laser scanning datasets have become more common, the use of laser scanning data has also increased. The advantage of the laser scanning method is especially in its ability to produce three-dimensional information of the area. Therefore, also vertical properties can be studied. The method’s advantage is its ability to detect changes in urban tree cover as well as in tree height. The aim of this study was to investigate how tree cover and especially canopy height have changed in the Kuninkaantammi area in Helsinki during 2008‒2015, 2015‒2017, 2017‒2020, and 2008‒2020 from multi-temporal laser scanning data. One of the starting points of this study was to find out how airborne laser scanning datasets with different sensors and survey parameters are suitable for change detection. Also, what kind of problems the differences between datasets will raise and how to reduce those problems. The study used laser scanning data from the National Land Survey of Finland and from the city of Helsinki for four different years. The canopy height models were produced of each dataset and changes were calculated as the difference of each canopy height model. The results show that multi-temporal laser scanning data require a lot of manual processing to create datasets comparable. The greatest problems were differences in point density and in classification of the data. The sparse data from the National Land Survey of Finland affected how changes were managed to be studied. Therefore, changes were detected only in general level. In addition, each dataset was classified differently which affected the usability of the classes in the datasets. The problems encountered were reduced by manual work like digitizing or by masking non-vegetation objects. The results showed that the change in the Kuninkaantammi area has been relatively large at the time of the study. Between 2008 and 2015, 12.1% of the tree cover was lost, 9.9% between 2015 and 2017, and 13.2% between 2017 and 2020. In addition, an increase in canopy height was detected. Between 2008 and 2015, 44.2% of the area had greater than 2 m increase in canopy height. Similarly, increase occurred in 11.1% and 3.5% of the area in 2015‒2017 and in 2017‒2020, respectively. Although the changes were observed at a general level, it can be concluded that the used datasets can provide valuable information about the changes in urban green that have taken place in the area.
  • Kaarto, Elli-Nora (2023)
    Agroforestry is a collective name for agricultural land-use practices where combinations of woody perennials such as trees and shrubs are intentionally managed with crops and/or livestock in same land units for various environmental and economic benefits. As a sustainable farming practice, agroforestry is used to increase food production without adding harmful impacts of agriculture on natural environment. Agroforestry is a common farming practice in Taita Hills, Kenya, where it is motivated by Kenyan policies supporting tree planting in the fields. This study aims to find out how canopy height and canopy cover have changed during the last ten years in the croplands of Taita Hills to get more knowledge on the state and trends of agroforestry in the study area. Changes in canopy height and canopy cover in croplands are approached by multitemporal airborne laser scanning (ALS) data. ALS is an active remote sensing method used to acquire three-dimensional point cloud data of a target landscape. Canopy height models (CHM), 99th percentile canopy height and canopy cover data were derived from two ALS data sets from 2014/2015 and 2022 and used for the change detection of canopy height and canopy cover during the study period. Field data from 2013 and 2022 containing tree measurements from 28 field plots were used in the validation of ALS-based analyses. The results indicate that there has been a slight increase in canopy height and canopy cover during the study period. It is acknowledged that the study period is quite short to detect changes in tree growth. Hence, only slight positive changes in canopy height and canopy cover were expected. Based on CHM changes, almost 20% of the area outside forests had ≥ 2 m increase in the canopy height. Furthermore, 7% of the area outside forests had ≤ -5 m decrease in the canopy height, which corresponds to tree loss. Results for CHM based canopy height were supported by 99th percentile canopy height changes. The area outside forest with ≥ 10% canopy cover increased from 67.4% to 68.0%. Even though canopy height and canopy cover had a slight increase in the croplands, forest cover was detected to be increasing during the study period. ALS and field measurements matched well with each other. In the tree height measurements, there were more variance with taller trees, probably caused by difficulties in measuring taller trees in the field. Moreover, ALS data was found to underestimate tree height changes. The average absolute deviation for tree height changes was 1.3 m shorter for ALS-measured tree heights than field measurements. Number of trees in field plots has mainly decreased during 20132022. ALS-based mean canopy height and canopy cover changes in the plots explain the actual changes well if large number of trees have been cut down during the study period. The thesis provides valuable information on the state and trends of agroforestry in Taita Hills. However, more exact land cover classification could have enhanced the accuracy of the results even more. All in all, the results were mainly positive, indicating that there has been an increasing trend in canopy height and canopy cover in the croplands in Taita Hills.
  • Downie, Eleanor (2023)
    The study of forest fragmentation, the break-up of forests into smaller patches, has become increasingly important due to increases in human-induced deforestation. Currently, approximately 12 million ha of forest are lost per year and 32% of this loss is tropical. There is substantial evidence showing that edge effects can alter the structure and functioning of remaining tropical forests, even hundreds of meters from the forest edge. However, implementing empirical experiments to understand the effects of fragmentation on forest structural metrics is logistically and scientifically challenging and limited to smaller areas. The use of forest models may help overcome these limitations, as they are able to quickly reproduce long-term ecological processes, as well as simulate a broad range of boundary forcings, such as biogeographical variability. This study evaluates the capability of a state-of-the-art forest dynamic model in reproducing the three-dimensional vertical distribution of plants in Amazonian forests affected by fragmentation. To achieve this, we optimized parameters driving plant demography and mortality, as well as their response to edge effects. FORMIND is an individual and process-based gap model suited for species rich vegetation communities, with the option of a fragmentation module. We modified processes and parameters in FORMIND to mimic the dynamics observed in a long-term (40 years-old) forest fragmentation experiment in the Brazilian Amazon. Forest structural metrics extracted from the FORMIND model output were compared with those obtained from terrestrial laser scans of the Amazonian Forest fragments. The resulting simulations demonstrated that, after 40 years of edge effects, the model in its original state was not capable of reproducing comparable results to those observed using the terrestrial LiDAR system. However, the addition of a new parameter capable of adjusting tree mortality at varying edge distances and inclusion of understory vegetation, drastically improved the model’s ability to replicate the three-dimensional distribution of plant material in the forest fragments. Total Plant Area Index (PAI), and PAI at varying height intervals (PAI 0-10m, PAI 10-20m, PAI 20-30m), amongst other metrics, showed consistent responses from edge effects, thus resulting in an adequate vertical plant distribution. Results demonstrate that, with the implementation of new parameters, forest models such as FORMIND have strong potential to study the mechanisms and the impact of environmental changes on forests. Models can also expand the possibilities of in-situ studies, which are limited in time and space, when calibrated carefully with suitable in-situ data, here delivered by terrestrial LiDAR.
  • Leppämäki, Tatu (2022)
    Ever more data is available and shared through the internet. The big data masses often have a spatial dimension and can take many forms, one of which are digital texts, such as articles or social media posts. The geospatial links in these texts are made through place names, also called toponyms, but traditional GIS methods are unable to deal with the fuzzy linguistic information. This creates the need to transform the linguistic location information to an explicit coordinate form. Several geoparsers have been developed to recognize and locate toponyms in free-form texts: the task of these systems is to be a reliable source of location information. Geoparsers have been applied to topics ranging from disaster management to literary studies. Major language of study in geoparser research has been English and geoparsers tend to be language-specific, which threatens to leave the experiences provided by studying and expressed in smaller languages unexplored. This thesis seeks to answer three research questions related to geoparsing: What are the most advanced geoparsing methods? What linguistic and geographical features complicate this multi-faceted problem? And how to evaluate the reliability and usability of geoparsers? The major contributions of this work are an open-source geoparser for Finnish texts, Finger, and two test datasets, or corpora, for testing Finnish geoparsers. One of the datasets consists of tweets and the other of news articles. All of these resources, including the relevant code for acquiring the test data and evaluating the geoparser, are shared openly. Geoparsing can be divided into two sub-tasks: recognizing toponyms amid text flows and resolving them to the correct coordinate location. Both tasks have seen a recent turn to deep learning methods and models, where the input texts are encoded as, for example, word embeddings. Geoparsers are evaluated against gold standard datasets where toponyms and their coordinates are marked. Performance is measured on equivalence and distance-based metrics for toponym recognition and resolution respectively. Finger uses a toponym recognition classifier built on a Finnish BERT model and a simple gazetteer query to resolve the toponyms to coordinate points. The program outputs structured geodata, with input texts and the recognized toponyms and coordinate locations. While the datasets represent different text types in terms of formality and topics, there is little difference in performance when evaluating Finger against them. The overall performance is comparable to the performance of geoparsers of English texts. Error analysis reveals multiple error sources, caused either by the inherent ambiguousness of the studied language and the geographical world or are caused by the processing itself, for example by the lemmatizer. Finger can be improved in multiple ways, such as refining how it analyzes texts and creating more comprehensive evaluation datasets. Similarly, the geoparsing task should move towards more complex linguistic and geographical descriptions than just toponyms and coordinate points. Finger is not, in its current state, a ready source of geodata. However, the system has potential to be the first step for geoparsers for Finnish and it can be a steppingstone for future applied research.
  • Päivärinta, Ronja (2023)
    Maantiede on hyvin visuaalinen oppiaine, ja erilaiset kartat ja kuvat ovat avainasemassa maantieteellisen tiedon esittämisessä ja ymmärtämisessä. Yhteiskunnan digitaalinen muutos ja teknologian kehitys ovat kuitenkin muokanneet maantieteen opetusta sekä opettajien käyttämiä materiaaleja merkittävästi. Digitaalisten materiaalien hyödyntämisestä onkin tullut maantieteen opettajille arkipäivää. Toisaalta digitaalisen materiaalin monimuotoisuus tarjoaa myös uusia mahdollisuuksia opettajille esimerkiksi opiskelijoiden osallistamisessa. Valtakunnalliset opetussuunnitelman perusteet painottavatkin nykyään maantieteessä digitaalisuutta sekä geomedian hyödyntämistä niin yläkoulussa kuin lukiossa. Tämä tutkielma on kvalitatiivinen tutkimus, jossa teemahaastatteluiden avulla on tutkittu maantieteen opettajien digitaalisten työkalujen käyttöä paikkatieto-opetuksessa sekä paikkatieto-opetuksen toteuttamisesta. Tutkimusta varten on haastateltu yhteensä 20 maantieteen aineenopettajaa. Haastattelujen perusteella opettajat käyttävät maantieteen opetuksessaan runsaasti digitaalista visuaalisuutta ja erilaisia digitaalisia työkaluja. Digitaalisten opetusmateriaalien käyttö korostuu erityisesti lukio-opettajilla. Sekä yläkoulun että lukion opettajat käyttävät osallistavassa geomedia opetuksessa digitaalisia työkaluja, kuten Googlen karttapalveluita. Toisaalta peruskoulun opettajat painottivat lukio-opettajia enemmän esimerkiksi diagrammien tai karttojen käsin paperille tekemistä. Paikkatieto-opetuksen toteutuksen kannalta sekä lukio- että peruskouluopettajat painottivat Googlen karttaselaimia. Sekä Google Maps että Google Earth olivat useiden käyttämiä työkaluja. Lukio-opettajilla korostui lisäksi vaativammat internetin karttapalvelut, kuten Paikkatietoikkuna tai jopa paikkatieto-ohjelmat, kuten ArcGIS Online. Opettajien valmiuteen käyttää erilaisia paikkatietosovelluksia vaikuttaa merkittävästi heidän oma osaamisensa. Kevyet matalan vaativuustason ohjelmat, kuten Googlen karttapalvelut, koetaan helpoiksi paikkatietoa opettaviksi alustoiksi ja työkaluiksi maantieteen opetuksessa. Vaativamman tason paikkatietosovellukset vaativat myös enemmän opettajan tietämystä sekä ymmärrystä paikkatiedosta. Tästä syystä monet opettajat kokevat ne usein haastaviksi tai hankaliksi opettaa. Sekä yläkoulussa että lukiossa myös aika ja maantieteen kurssien hektisyys ja kiire sekä muiden opetettavien maantieteen aiheiden priorisoiminen vaikuttavat paikkatieto-opetuksen toteutumiseen ja taitojen opettamiseen. Erityisesti lukio-opettajat kokevat maantieteen moduulien olevan niin täynnä asiaa, että paikkatieto-opetukselle ei jää kunnolla aikaa muualle, kuin viimeiseen geomedian moduuliin. Tutkimuksen perusteella voidaan yhteenvetona todeta, että paikkatieto-opetus toteutuu hyvin vaihtelevasti opettajasta sekä opetusasteesta riippuen. Erityisesti opettajan taidot sekä muut resurssit vaikuttavat merkittävästi siihen, millaisia digitaalisia työkaluja opettajat hyödyntävät paikkatieto-opetuksessa.
  • Perola, Eero (2023)
    Driving speeds regardless of vehicle type are a part of almost everyone’s daily lives. The subject has been widely studied and many algorithms for determining optimal routes exist. A novel data source for this type of research is GPS-collected Floating Car Data. As positioning enabled devices have become increasingly abundant, the collection of huge amounts of data with locations, speeds and directions has become vastly more common. In this master’s thesis, I examine a type of Big Data -set of car speeds within the Helsinki area through three different viewpoints. First, I examine the driving patterns described by the distribution of data on different kinds of roads and time periods. Second, I focus on one variable, intersection density, and determine the effect it has on the change in speed and whether it is possible to conduct statistical analysis for the data. Last, I analyze the steps needed to take in order to fully utilize the variables of the data within the road network system. The results indicate that while there are clear differences in changing speed within road classes, the differences are not as clearly described by road class as they are by speed limit. Also, time of day has a clear effect where times of congestion are distinguishable. While among all road classes the mean driven speed is below the speed limit, on larger roads the mode is above the speed limit. I prove that it is possible to find numerous variables that depict speed change through novel Floating Car Data. Focusing on intersection density, the result is that at highest, within the Helsinki area, intersection density represents around eight per cent of change in speed compared to speed limit. As a final result, a method to viably use linear Floating Car Data to research intersection density and its effects is developed. As a mediate step and a side result, a workflow of modifying road network layers into segments between intersections is produced.
  • Saarimaa, Saku (2022)
    Recent studies on day-care staff have reported on problems in hiring qualified staff, and in increased resignations in existing staff. These problems are connected to an increase in workload and stress, and reduced wellbeing at work. When workload and challenges in day-care work increase, there can even be a risk of diminishing the pedagogical quality of education. The problems seem to occur differently and in different magnitudes in different day-care units, which indicates learning conditions’ possible segregation. In the case of schools, the socioeconomic status of nearby population has been noticed to affect children’s predisposed abilities to learn, and their support requirements in learning. This effect can be assumed to affect early childhood education similarly, which would lead to day-cares in socioeconomically disadvantaged areas to require extra resources and staff to compensate for the children’s increased support requirements. If those extra resources are not available, the staff will experience increased workload and stress, which will cause problems in the long term. The city is known to be somewhat socioeconomically segregated, and if this is mirrored in day-cares so that the backgrounds of children in day-cares get segregated, it may also start to affect the quality of education. In this case the unevenly distributed challenges would cause institutional segregation of learning conditions in early childhood education. The institutional segregation of early childhood education or schools has not been studied much in Finland. Earlier studies on Finnish schools have been able to explain differences between schools through differences in children’s backgrounds, and there has not been a reason to doubt the institutional equality of schools’ quality. The basic principle of the Finnish early childhood education and school system is to provide every child with equal conditions and opportunities to grow and learn. These equal conditions equalise segregation in the population by offering equally high-quality education in both disadvantaged and well-off areas of the city. However, if the segregation of children’s backgrounds is accompanied by the segregation of learning conditions in day-cares, there is a risk of the cumulation of both socioeconomic disadvantage and lower quality of education. In this case, the quality would decrease exactly where it would be most needed. In my thesis I study whether there is differentiation in problems related to hiring or keeping staff in the day-cares in Helsinki, through the numbers of resigned and unqualified staff in each unit. I also look at whether this segregation of day-care units is at all related to the socioeconomic segregation of the city’s population. In the study I utilize HR data from the city of Helsinki and socioeconomic population data from Statistics Finland, which I join onto spatial data of day-cares’ locations. I use this combined dataset to study the segregation of day-cares and its connections to socioeconomic segregation using quantitative statistical methods and spatial analysis methods. The results indicate that there is perceivable segregation in the staff of day-cares in Helsinki, but socioeconomic segregation is able to statistically explain the patterns only slightly. Therefore, mostly other phenomena seem to cause the differentiation in staff related problems, but these phenomena are not yet known. In terms of institutional segregation, the early childhood education system in Helsinki seems to still be quite equal. However, more knowledge about the subject is needed, because both the results in this study, as well as previous studies show some worrying signals pointing to the possibility of institutional segregation. In addition, intense public discourse around the topic of early childhood education, and a wide-ranging worker’s strike, including day-care staff, seem demonstrative of the seriousness of these challenges in day-cares.
  • Heinonen, Roope (2024)
    Active travel modes are gaining popularity for their positive physical and mental health and envi- ronmental benefits. Active travelers are more exposed to environmental variables than other road users. These environmental exposures have various positive and negative effects on travelers’ well- being. The major global routing platforms, such as Google Maps or Apple Maps, do not include any transparent use of environmental variables for path finding or visualization, despite the scientific evidence. I aim to study route planning tools from an environmental exposure perspective to understand the current support for exposure-optimized routes better. A route planning tool review shows that current platforms lack support for environmental exposures. Scientific research on environmental exposures needs more variety, transferability, and reproducibility. These results indicate that more robust, transferable, and flexible multi-objective environmental exposure optimization tools are needed. Such a tool would benefit many different groups of people, from experts such as planners and scientists to ordinary citizens. In this thesis, I set out to develop a powerful and flexible multi-objective routing tool. This tool aims to quantify and optimize environmental exposures during active travel. To achieve this, I designed a tool that supports route planning with active travel modes, supporting individual routes and mass calculations without spatial restrictions. This tool supports various exposure data types of raster and vector, such as greenery, noise, and air quality. To power this tool, I utilized Conveyal’s r5 routing engine. To showcase the tool’s applicability and configurability, I ran the tool and altered combinations of routing strategies, cities, exposure data sources, and configurations. The results show that creating a flexible multi-objective environmental exposure routing platform is viable. Data qualities such as exposure data coverage, data buffers, and weights can significantly affect the exposure results and paths. This thesis proves that this type of flexible environmental exposure-supporting routing tool can have great potential to support environmentally sustainable development, active travel environmental exposure studies, and individual exposure-optimized route planning. Further research is required to better understand how different environmental exposures accumulate during travel and affect active travelers’ well-being
  • Toikka, Akseli (2019)
    Urban vegetation has traditionally been mapped through traditional ways of remote sensing like laser scanning and aerial photography. However, it has been stated that the bird view examination of vegetation cannot fully represent the amount of green vegetation that the citizens observe on street level. Recent studies have raised human perspective methods like street view images and measuring of green view next to more traditional ways of mapping vegetation. Green view index states the percentage of green vegetation in street view on certain location. The purpose for this study was to create a green view dataset of Helsinki city through street view imagery and to reveal the differences between human perspective and aerial perspective in vegetation mapping. Street view imagery of Helsinki was downloaded from Google street view application interface. The spatial extent of the data was limited by the availability of street view images of summer months. Several green view maps of Helsinki were created based on the green view values calculated on the street view images. In order to understand the differences between human perspective and the aerial view, the green view values were compared with the regional land cover dataset of Helsinki trough linear regression. Areas with big differences between the datasets were examined visually through the street view imagery. Helsinki green view was also compared internationally with other cities with same kind of data available. It appealed that the green view of Helsinki was divided unequally across the city area. The lowest green view values were found in downtown, industrial areas and the business centers of the suburbs. Highest values were located at the housing suburbs. When compared with the land cover, it was found that the green view has a weak correlation with low vegetation and relatively high correlation with taller vegetation such as trees. Differences between the datasets were mainly concentrated on areas where the vegetation was not visible from the street by several reasons. Main sources of errors were the oldest street view images and the flaws in image classification caused by other green objects and shadows. Even though Helsinki has many parks and other green spaces, the greenery visible to the streets isn’t always that high. The green view dataset created in this study helps to understand the spatial distribution of street greenery and brings human perspective next to more traditional ways of mapping city vegetation. When combined with previous city greenery datasets, the green view dataset can help to build up more holistic understanding of the city greenery in Helsinki
  • Torkko, Jussi (2021)
    Urban greenery is vital to the people in our increasingly urbanizing societies. It is diverse in nature and provides numerous life improving qualities. Traditionally urban greenery has been assessed with a top-down view through the sensors of aerial vehicles and satellites. This does not equate on what is experienced down at the human level. An alternative viewpoint has emerged, with the introduction of a more human-scale viewpoint. To quantify this human-scale greenery, novel and disparate approaches have been developed. However, there is little knowledge on how these modelling methods and indices manage to capture the greenery we truly experience on the ground level. This thesis is an undertaking to better understand what the greenery experienced by people on the ground level, termed humanscale greenery (HSG), means. The goal was to grasp how the various modelling methods, indices and datasets can be best used to capture this phenomenon. Simultaneously, the study tries to better comprehend how different people experience greenery. To achieve this, human-scale greenery values were collected via interviews at randomly selected study sites across Helsinki. These values were then compared to modelled values at the same sites. The methods and indices tested include modern approaches developed specifically for HSG and traditional greenery assessment methods. Along the greenery values, sociodemographic variables were collected in the interviews and compared to each other in relation to HSG values. The modelled values were on average smaller than HSG values. All methods indicated very strong or strong linear relationships with human-scale greenery. NDVI and semantic segmentation Green View Index (GVI) had the strongest relationships and least deviation. Land use (LU) and color based GVI had the highest error deviations from HSG. The sociodemographic assessment showed hints that age might affect the amount of experienced greenery, but this is uncertain. With a random sampling of interviewees, 25–34-year-olds and less nature visiting people were more common at sites with low HSG. Based on the results obtained here, many different types of novel methods are suitable for modelling HSG with strong linear relationships. However, also traditional greenery assessment methods performed well. It is difficult to curtail the experience of greenery into a single approach. A solution could possibly be obtained via the combination of methods. The results also advocate the usage of machine learning methods for greenery image segmentation. These cannot be applied everywhere due to data coverage problems, but alternative methods can also be used to fill in gaps. The significance of age on the experience of greenery needs further research. Because urban greenery’s benefits are known, attention should also be given onto how different kinds of people are able to experience it. In the future we should also discuss the meaningfulness of assessing absolute greenery in comparison to the types and parts of greenery.
  • Rantanen, Olli (2020)
    Uuden tieliikennelain mukanaan kunnille tuomat velvoitteet, kuten liikenteenohjaukseen käytetyn välineistön (esim. liikennemerkkien) ylläpitovastuu, siirtyy kunnille 1.6.2020. Kenttäinventoimalla suoritettava liikennemerkkien kunnon ja sijainnin selvittäminen on usein työlästä ja tuottaa kustannuksia. Tässä tutkimuksessa selvitetään, miten näitä voidaan automatisoidusti inventoida panoraamakuvilta. Samalla verrataan panoraamakuvien ja niistä luotujen osakokonaisuuksien (pilkottujen kuvien) soveltuvuutta kyseiseen tarkoitukseen. Tunnistuksen tuloksena syntyviä havaintoja verrataan Väyläviraston ylläpitämään avoimeen liikennemerkkiaineistoon sekä tunnistettujen kohteiden sijainti lasketaan kuvilta. Työssä tutustutaan myös eri kohteentunnistusalgoritmien toimintaan sekä selvitetään, miten liikennemerkkien automaattisessa tunnistuksessa on onnistuttu muissa tutkimuksissa. Aineistona toimii Inkoosta otettujen panoraamakuvien lisäksi Mapillaryn toimittamat kuva-aineistot, joita käytetään YOLOv3-kohteentunnistusalgoritmin koulutukseen ja testaukseen. Työssä esitellään myös YOLOv3-koulutuksen toteuttaminen ja käydään läpi tarvittavat ohjelmistot sen implementoinnissa toiseen työhön. Koulutus vaatii riittävän GPU:n lisäksi erilaisia ohjelmia sekä runsaasti kuva-aineistoa, jotta ylisovittamisen riskiltä vältytään. Tulosten perusteella pilkotut kuvat tuottavat paremman tuloksen verrattuna panoramakuviin. Pilkotuilta kuvilta jokainen ajoreitin varrella ollut kärkikolmio tunnistettiin, kun taas panoraamakuvilta tämä ei onnistunut. Lisäksi algoritmin kyky sijoittaa kärkikolmion sijainti kuvalle oli varsin hyvä saavuttaen keskimäärin IoU-arvon 0,86, kun se panoraamoilla oli 0,52. Samoin tulosten luotettavuutta kuvaavat Precision- ja Recall-arvot olivat huomattavasti korkeammat kuin panoraamakuvilla. Työssä havaittiin lisäksi, että Väyläviraston avoimesta aineistosta puuttuu useita kärkikolmioita. Kuvilta onnistuttiin myös laskemaan muutaman metrin tarkkuudella kärkikolmioiden sijainti maastossa. Tutkimuksen perusteella kohteentunnistusalgoritmit tuottavat merkittävää hyötyä kohteiden automaattisessa tunnistuksessa. Algoritmien hyödyntämistä tulevaisuudessa mahdollistaa lisääntyvä kuva-aineistojen määrä sekä laskentatehon kasvu. Hyödyntämällä kohteentunnistusalgoritmeja kuntien on mahdollista helpottaa uuden tieliikennelain velvoitteiden noudattamista. Tämän myötä algoritmien suosio voi kasvaa tulevaisuudessa. Kohteentunnistusalgoritmien implementointiin tarvitaan kuitenkin ohjeistusta ja käyttötapauksia, joita tämä tutkimus tuloksillaan edistää.