Most of spatial data extraction and updating procedures require digitization of geographical entities from satellite imagery. During digitization, errors are introduced by factors like instrument deficiencies or user errors. In this study positional uncertainty of geographical objects, digitized from high resolution Quickbird satellite imagery, is assessed using Data Uncertainty Engine (DUE). It is a software tool for assessing uncertainties in environmental data / and generating realisations of uncertain data for use in uncertainty propagation analyses. A case study area in Kocaeli, Turkey that mostly includes agricultural land parcels is selected in order to evaluate positional uncertainty and obtain uncertainty boundaries for manually digitized fields. Geostatistical evaluation of discrepancy between reference data and digitized polygons are undertaken to analyse auto and cross correlation structures of errors. This process is utilized in order to estimate error model parameters which are employed in defining an uncertainty model within DUE. Error model parameters obtained from training data, are used to generate simulations for test data. Realisations of data derived via Monte Carlo Simulation using DUE, are evaluated to generate uncertainty boundaries for each object guiding user for further analyses with pre-defined information related to the accuracy of spatial entities. It is also aimed to assess area uncertainties affected by the position of spatial entities. For all different correlation structures and object models, weighted average positional error for this study is between 2.66 to 2.91 meters. At the end of uncertainty analysis, deformable object model produced the smallest uncertainty bandwidth by modelling cross correlation.

Embora o tema planejamento de redes geodésicas seja largamente investigado, especialmente a partir da segunda metade da década de 70, no âmbito nacional, poucos estudos são encontrados relativos ao planejamento de redes geodésicas, especialmente por meio de simulações numéricas. Recentemente, KLEIN (2014) propôs um método para o planejamento de redes geodésicas (denominado aqui de Método Klein – MK), solucionado por meio de tentativa e erro. Dentro desse contexto objetivo deste trabalho é propor melhorias e adaptar o MK para redes horizontais por meio de simulações numéricas, algo que ainda não é encontrado na Literatura aplicado à otimização de redes. No referido método, cada vez que a rede é reprovada em algum dos critérios considerados, necessita-se de um incremento feito com base na expertise do usuário. Neste trabalho foi desenvolvido um programa (em código aberto) para tornar o método independente de decisões por parte do usuário com o objetivo de tornar o MK viável. Enquanto o geodesista testa decisões em um espaço limitado de opções (por tentativa e erro), a proposta desenvolvida nessa pesquisa testa à exaustão todas as possibilidades do problema por simulações numéricas. Para isso, o usuário deve informar, além dos parâmetros considerados no MK, as seguintes informações: as coordenadas dos pontos de controle (suas precisões e direção(ões) do(os) azimute(es)); as coordenadas aproximadas dos pontos desconhecidos; quais observações serão usadas inicialmente; possíveis novas observações e, por fim, os equipamentos disponíveis. Foram implementadas três estratégias visando minimizar o custo na etapa de planejamento, em ordem crescente de custo, são elas: repetição das observações originalmente propostas (E1); adição de novas visadas (E2) e troca de equipamento por outro de maior precisão (E3). O programa desenvolvido foi testado em três experimentos usando dados provenientes de uma rede real implantada no entorno do campus Florianópolis do Instituto Federal de Santa Catarina e simulando o uso de três equipamentos distintos. Os resultados obtidos mostram que as adaptações tornaram o MK viável do ponto de vista prático e os objetivos propostos foram concluídos com sucesso. Entre as conclusões obtidas deve-se citar: existe uma limitação para incerteza final da rede em função do equipamento utilizado; as visadas adicionais devem ser combinadas de forma a diminuir o número de estações entre os pontos de controle e os vértices desconhecidos da rede; a melhor maneira de aumentar consideravelmente o nível de confiabilidade de uma observação é repetindo-a. Por fim, são feitas considerações sobre as limitações do método proposto: dificuldade do usuário em encontrar valores ideais para a incerteza final da rede; interface visual pouco amigável; método limitado a redes horizontais; e ausência da variável custo de maneira quantitativa na etapa de planejamento. / Although the topic of geodetic network planning has been extensively investigated, especially since the second half of the 1970s, at the national level, few studies have been carried out regarding the planning of geodetic networks, especially through numerical simulations. Recently, KLEIN (2014) proposed a method for the planning of geodesic networks (here called Klein - MK Method), solved by trial and error. Within this context, the objective of this work is to propose improvements and to adapt the MK to horizontal networks through numerical simulations, something that is not yet found in Literature applied to network optimization. In Klein’s work, each time the network is disapproved in any of the considered criteria, an increment is necessary based on the user's expertise. In this work, a program (open source) was developed to make the method independent of user’s decisions with the objective of disseminating the Klein Method (MK) in the related community. While the geodesist tests decisions in a limited range of options (by trial and error), the proposal developed in this paper exhausts all possibilities of the problem by numerical simulations. For this, the user must inform, in addition to the parameters considered in the MK, the following information: coordinates control points (their precisions and direction (s) of the azimuth (s)); approximate coordinates of the unknown points; which observations will be used initially; new possible observations and, finally, the available equipments. Three strategies were implemented in order to minimize the cost of the designing step, in order of increasing cost, they are: repetition of the originally proposed observations (E1); Addition of new sights (E2) and exchange of equipment for another one of better precision (E3). The developed program was tested in three experiments using data from a real network implanted in the surroundings of Florianópolis campus of the Federal Institute of Santa Catarina and simulating the use of three different equipments. Satisfactory results were obtained and the proposed objectives were successfully completed. Among the conclusions obtained should be mentioned: there is a limitation for the final accuracy of the network according to the equipment used; additional sights must be combined in such a way to reduce the number of stations between control points and unknown vertices of the network; The best way to greatly increase the level of reliability of an observation is by repeating it. Finally, considerations are made about the limitations of the proposed method: the difficulty of the user to find ideal values for the final uncertainty of the network; Unfriendly visual interface; Method limited to horizontal networks and absence of quantitative cost analysis in the planning step.

Embora o tema planejamento de redes geodésicas seja largamente investigado, especialmente a partir da segunda metade da década de 70, no âmbito nacional, poucos estudos são encontrados relativos ao planejamento de redes geodésicas, especialmente por meio de simulações numéricas. Recentemente, KLEIN (2014) propôs um método para o planejamento de redes geodésicas (denominado aqui de Método Klein – MK), solucionado por meio de tentativa e erro. Dentro desse contexto objetivo deste trabalho é propor melhorias e adaptar o MK para redes horizontais por meio de simulações numéricas, algo que ainda não é encontrado na Literatura aplicado à otimização de redes. No referido método, cada vez que a rede é reprovada em algum dos critérios considerados, necessita-se de um incremento feito com base na expertise do usuário. Neste trabalho foi desenvolvido um programa (em código aberto) para tornar o método independente de decisões por parte do usuário com o objetivo de tornar o MK viável. Enquanto o geodesista testa decisões em um espaço limitado de opções (por tentativa e erro), a proposta desenvolvida nessa pesquisa testa à exaustão todas as possibilidades do problema por simulações numéricas. Para isso, o usuário deve informar, além dos parâmetros considerados no MK, as seguintes informações: as coordenadas dos pontos de controle (suas precisões e direção(ões) do(os) azimute(es)); as coordenadas aproximadas dos pontos desconhecidos; quais observações serão usadas inicialmente; possíveis novas observações e, por fim, os equipamentos disponíveis. Foram implementadas três estratégias visando minimizar o custo na etapa de planejamento, em ordem crescente de custo, são elas: repetição das observações originalmente propostas (E1); adição de novas visadas (E2) e troca de equipamento por outro de maior precisão (E3). O programa desenvolvido foi testado em três experimentos usando dados provenientes de uma rede real implantada no entorno do campus Florianópolis do Instituto Federal de Santa Catarina e simulando o uso de três equipamentos distintos. Os resultados obtidos mostram que as adaptações tornaram o MK viável do ponto de vista prático e os objetivos propostos foram concluídos com sucesso. Entre as conclusões obtidas deve-se citar: existe uma limitação para incerteza final da rede em função do equipamento utilizado; as visadas adicionais devem ser combinadas de forma a diminuir o número de estações entre os pontos de controle e os vértices desconhecidos da rede; a melhor maneira de aumentar consideravelmente o nível de confiabilidade de uma observação é repetindo-a. Por fim, são feitas considerações sobre as limitações do método proposto: dificuldade do usuário em encontrar valores ideais para a incerteza final da rede; interface visual pouco amigável; método limitado a redes horizontais; e ausência da variável custo de maneira quantitativa na etapa de planejamento. / Although the topic of geodetic network planning has been extensively investigated, especially since the second half of the 1970s, at the national level, few studies have been carried out regarding the planning of geodetic networks, especially through numerical simulations. Recently, KLEIN (2014) proposed a method for the planning of geodesic networks (here called Klein - MK Method), solved by trial and error. Within this context, the objective of this work is to propose improvements and to adapt the MK to horizontal networks through numerical simulations, something that is not yet found in Literature applied to network optimization. In Klein’s work, each time the network is disapproved in any of the considered criteria, an increment is necessary based on the user's expertise. In this work, a program (open source) was developed to make the method independent of user’s decisions with the objective of disseminating the Klein Method (MK) in the related community. While the geodesist tests decisions in a limited range of options (by trial and error), the proposal developed in this paper exhausts all possibilities of the problem by numerical simulations. For this, the user must inform, in addition to the parameters considered in the MK, the following information: coordinates control points (their precisions and direction (s) of the azimuth (s)); approximate coordinates of the unknown points; which observations will be used initially; new possible observations and, finally, the available equipments. Three strategies were implemented in order to minimize the cost of the designing step, in order of increasing cost, they are: repetition of the originally proposed observations (E1); Addition of new sights (E2) and exchange of equipment for another one of better precision (E3). The developed program was tested in three experiments using data from a real network implanted in the surroundings of Florianópolis campus of the Federal Institute of Santa Catarina and simulating the use of three different equipments. Satisfactory results were obtained and the proposed objectives were successfully completed. Among the conclusions obtained should be mentioned: there is a limitation for the final accuracy of the network according to the equipment used; additional sights must be combined in such a way to reduce the number of stations between control points and unknown vertices of the network; The best way to greatly increase the level of reliability of an observation is by repeating it. Finally, considerations are made about the limitations of the proposed method: the difficulty of the user to find ideal values for the final uncertainty of the network; Unfriendly visual interface; Method limited to horizontal networks and absence of quantitative cost analysis in the planning step.

Embora o tema planejamento de redes geodésicas seja largamente investigado, especialmente a partir da segunda metade da década de 70, no âmbito nacional, poucos estudos são encontrados relativos ao planejamento de redes geodésicas, especialmente por meio de simulações numéricas. Recentemente, KLEIN (2014) propôs um método para o planejamento de redes geodésicas (denominado aqui de Método Klein – MK), solucionado por meio de tentativa e erro. Dentro desse contexto objetivo deste trabalho é propor melhorias e adaptar o MK para redes horizontais por meio de simulações numéricas, algo que ainda não é encontrado na Literatura aplicado à otimização de redes. No referido método, cada vez que a rede é reprovada em algum dos critérios considerados, necessita-se de um incremento feito com base na expertise do usuário. Neste trabalho foi desenvolvido um programa (em código aberto) para tornar o método independente de decisões por parte do usuário com o objetivo de tornar o MK viável. Enquanto o geodesista testa decisões em um espaço limitado de opções (por tentativa e erro), a proposta desenvolvida nessa pesquisa testa à exaustão todas as possibilidades do problema por simulações numéricas. Para isso, o usuário deve informar, além dos parâmetros considerados no MK, as seguintes informações: as coordenadas dos pontos de controle (suas precisões e direção(ões) do(os) azimute(es)); as coordenadas aproximadas dos pontos desconhecidos; quais observações serão usadas inicialmente; possíveis novas observações e, por fim, os equipamentos disponíveis. Foram implementadas três estratégias visando minimizar o custo na etapa de planejamento, em ordem crescente de custo, são elas: repetição das observações originalmente propostas (E1); adição de novas visadas (E2) e troca de equipamento por outro de maior precisão (E3). O programa desenvolvido foi testado em três experimentos usando dados provenientes de uma rede real implantada no entorno do campus Florianópolis do Instituto Federal de Santa Catarina e simulando o uso de três equipamentos distintos. Os resultados obtidos mostram que as adaptações tornaram o MK viável do ponto de vista prático e os objetivos propostos foram concluídos com sucesso. Entre as conclusões obtidas deve-se citar: existe uma limitação para incerteza final da rede em função do equipamento utilizado; as visadas adicionais devem ser combinadas de forma a diminuir o número de estações entre os pontos de controle e os vértices desconhecidos da rede; a melhor maneira de aumentar consideravelmente o nível de confiabilidade de uma observação é repetindo-a. Por fim, são feitas considerações sobre as limitações do método proposto: dificuldade do usuário em encontrar valores ideais para a incerteza final da rede; interface visual pouco amigável; método limitado a redes horizontais; e ausência da variável custo de maneira quantitativa na etapa de planejamento. / Although the topic of geodetic network planning has been extensively investigated, especially since the second half of the 1970s, at the national level, few studies have been carried out regarding the planning of geodetic networks, especially through numerical simulations. Recently, KLEIN (2014) proposed a method for the planning of geodesic networks (here called Klein - MK Method), solved by trial and error. Within this context, the objective of this work is to propose improvements and to adapt the MK to horizontal networks through numerical simulations, something that is not yet found in Literature applied to network optimization. In Klein’s work, each time the network is disapproved in any of the considered criteria, an increment is necessary based on the user's expertise. In this work, a program (open source) was developed to make the method independent of user’s decisions with the objective of disseminating the Klein Method (MK) in the related community. While the geodesist tests decisions in a limited range of options (by trial and error), the proposal developed in this paper exhausts all possibilities of the problem by numerical simulations. For this, the user must inform, in addition to the parameters considered in the MK, the following information: coordinates control points (their precisions and direction (s) of the azimuth (s)); approximate coordinates of the unknown points; which observations will be used initially; new possible observations and, finally, the available equipments. Three strategies were implemented in order to minimize the cost of the designing step, in order of increasing cost, they are: repetition of the originally proposed observations (E1); Addition of new sights (E2) and exchange of equipment for another one of better precision (E3). The developed program was tested in three experiments using data from a real network implanted in the surroundings of Florianópolis campus of the Federal Institute of Santa Catarina and simulating the use of three different equipments. Satisfactory results were obtained and the proposed objectives were successfully completed. Among the conclusions obtained should be mentioned: there is a limitation for the final accuracy of the network according to the equipment used; additional sights must be combined in such a way to reduce the number of stations between control points and unknown vertices of the network; The best way to greatly increase the level of reliability of an observation is by repeating it. Finally, considerations are made about the limitations of the proposed method: the difficulty of the user to find ideal values for the final uncertainty of the network; Unfriendly visual interface; Method limited to horizontal networks and absence of quantitative cost analysis in the planning step.

Laserskanning har blivit en vanlig metod för dokumentation, övervakning, underhåll och ut­veckling av olika industrimiljöer. Särskilt för inmätning och visualisering av komplexa rörledningar på industrianläggningars tak är punktmoln från laserskanning ett viktigt verktyg för att på ett enkelt sätt hitta potentiella platser för installation av nya rörledningar. Detta examensarbete genomfördes i samarbete med konsultbolaget Swecos mätningsgrupp i Karlstad och undersökte om det är möj­ligt att ersätta punktmoln från terrester laserskanning med punktmoln skapade med flygbilder tagna med UAS (Unmanned Aerial System) för dokumentering av komplexa rördragningar på industritak. Studien genomfördes på ett mindre område (5x25 m) på reningsverket i stadsdelen Sjöstad (Sjö­stadsverket) i Karlstad. Området innehöll omfattande rörledningar i olika dimensioner och andra detaljer såsom rattar, flänsar och gallerluckor. Detta område ansågs därför vara lämpligt att använda för studiens syfte och tillträdet förutsatte dessutom inte omfattande och dyra säkerhetsutbildningar. Undersökningen genomfördes genom markering av ett sextiotal kontrollpunkter som sedan mättes in med totalstation i ett lokalt referenssystem. Bakåtobjekten användes även som fästpunkter för sfäriska måltavlor under laserskanningen. Dessutom mättes även målade markstödsignaler på bet­ongen in i samband med detta för att möjliggöra en georeferering av flygbilderna. Därefter genom­fördes terrester laserskanning inom undersökningsområdet från nio uppställningar med varierande instrumenthöjder samt två UAS-flygningar med flygfotografering från tio respektive 22 m flyghöjd. Efterbearbetningarna började med att etablera ett lokaltreferenssystem, vilket användes för geo­referering av både laserskanningspunkmolnet samt respektive flygfotograferingspunktmoln. De er­hållna lokala koordinaterna för kontrollpunkterna i respektive punktmoln jämfördes gentemot de totalstationsinmätta koordinaterna för att analysera lägesosäkerheten. Punktmolnet från terrester laserskanning innehöll 55 tydligt identifierbara kontrollpunkter medan punktmolnen från UAS-flygningen visade 53 respektive 22 identifierbara kontrollpunkter. Den kvadratiska medelavvikelsen (RMS) i 3D för dessa punkter uppgick till 8 mm i laserskann­ingspunktmolnet respektive 25 mm för båda flygbildspunktmoln. Efter detta analysmoment valdes punktmolnet från flygningen på 22 m höjd bort inför de fortsatta analyserna då cirka två tredjedelar av kontrollpunkterna inte var identifierbara. Även mät- och lägesosäkerheten från flygbildspunktmolnet från tio meters höjd visade sig dock i början vara otillräckligt för att kunna ersätta terrester laserskanning med flygfotografering med UAS. Ändå tillät detaljeringsgraden en identifiering av ett stort antal kontrollpunkter och vidare analyser visade att den stora lägesosäkerheten främst berodde på kontrollpunkter kopplade till vissa detaljtyper (dolda stödben och omarkerade bultar). En nyberäkning av lägesosäkerheten utan dessa kontrollpunkter gav betydligt bättre värden för lägesosäkerhet inom flygbildspunktmolnet från tio meters höjd, ett RMS i 3D på 12 mm. Eftersom användningarna där Sweco skulle vilja ersätta terrester laserskanning med flygfoto­graf­ering inte kräver en detaljnivå på bultstorlek visade sig därmed flygfotografering med UAS som en lämplig alternativ metod för att dokumentera komplexa rördragningar på industritak. / This study explored the possibility of using aerial photography from Unmanned Aerial Systems (UAS) as a replacement for terrestrial laser scanning in documenting complex pipeline systems on industrial roofs. The research, conducted in collaboration with Sweco's survey group in Karlstad, focused on visual qualities and positional uncertainty in point clouds generated by terrestrial laser scanning and aerial photography. Control points were marked and surveyed using a total station, then terrestrial laser scanning and UAS-aerial photography was performed to generate point clouds. Analysis revealed that the aerial photography at 22 m altitude was not suitable due to unrecognizable control points. However, the aerial photography at 10 m altitude, after excluding certain types of control points, showed improved positional uncertainty. As the desired applications did not require fine-level detail, UAS aerial photography proved to be a suitable alternative for documenting complex pipeline systems on industrial roofs.

I samband med en trafikolycka är det ofta viktigt att återställa platsen till det normala så snabbt som möjligt. Emellanåt måste olycksplatsen dokumenteras för att orsaken till olyckan ska kunna utredas i ett senare skede. Traditionellt har detta arbete utförts genom att fotografera platsen och mäta olika avstånd. På senare tid har även terrester laserskanning kommit att bli ett tillförlitligt alternativ. Med det sagt är det tänkbart att även fotogrammetri och andra typer av laserskanning skulle kunna användas för att uppnå liknande resultat.  Syftet med denna studie är att utforska hur handhållen laserskanning och UAS-fotogrammetri kan användas för att dokumentera en trafikolycka. Detta uppnås genom att utvärdera punktmolnens lägesosäkerhet och visuella kvalitet. Vidare utforskas fördelar och nackdelar med respektive metod, bland annat sett till tidsåtgång och kostnader, för att slutligen komma fram till vilken metod som lämpar sig bäst för att dokumentera en trafikolycka.  En trafikolycka med två inblandade bilar iscensattes och laserskannades till en början med den handhållna laserskannern Leica BLK2GO. Därefter samlades bilder in med den obemannade flygfarkosten Leica Aibot följt av att ett referenspunktmoln skapades med den terrestra laserskannern Leica C10. Genom att jämföra koordinater för kontrollpunkter i referenspunktmolnet med koordinaterna för motsvarande kontrollpunkter i de två andra punktmolnen kunde deras lägesosäkerheter bestämmas. Studiens resultat visar att både punktmolnet som framställdes med handhållen laserskanning och UAS-fotogrammetri har en lägesosäkerhet (standardosäkerhet) i 3D på 0,019 m. Båda metoderna är tillämpliga för att dokumentera en trafikolycka, men jämfört med terrester laserskanning är punktmolnen dock bristfälliga på olika sätt. BLK2GO producerar ett förhållandevis mörkt punktmoln och mörka objekt avbildas sämre än ljusare föremål. I punktmolnet som framställdes med Leica Aibot förekom påtagliga håligheter i bilarnas karosser. Handhållen laserskanning är en tidseffektiv metod medan UAS-fotogrammetri kan utföras till en lägre kostnad. Sammanfattningsvis går det inte att dra någon entydig slutsats om vilken metod som lämpar sig bäst för att dokumentera en trafikolycka. Valet beror på vilka omständigheter som råder på olycksplatsen. / In the event of a traffic accident, it is often important to restore the site to its normal condition as fast as possible. Occasionally, the accident scene must be documented so that the cause of the accident can be investigated at a later stage. Traditionally, this work has been performed by taking pictures of the site and measuring different distances. Lately, terrestrial laser scanning has also become a reliable alternative. With that said, it is possible that photogrammetry and other types of laser scanning also could be utilized to achieve similar results.    The aim of this study is to investigate how handheld laser scanning and UAS photogrammetry can be used to document a traffic accident. This is achieved by examining the positional uncertainty and visual quality of the point clouds. Moreover, the advantages and disadvantages of each method are explored, for instance in terms of time consumption and costs, in order to finally come to a conclusion of which method is best suited for documenting a traffic accident. A traffic accident with two involved cars was staged and initially laser scanned with the handheld laser scanner Leica BLK2GO. Thereafter, pictures were collected with the unmanned aerial vehicle Leica Aibot followed by the creation of a reference point cloud with the terrestrial laser scanner Leica C10. By comparing the coordinates of control points in the reference point cloud with the coordinates of the corresponding control points in the two other point clouds, their positional uncertainty could be determined. The results of the study show that both the point cloud produced by the handheld laser scanner and UAS photogrammetry have a positional uncertainty (standard uncertainty) of 0.019 m. Both methods are applicable for documenting a traffic accident but compared to terrestrial laser scanning, the point clouds are deficient in different ways. BLK2GO produces a relatively dark point cloud and dark objects are reproduced worse than lighter objects. In the point cloud produced by Leica Aibot, there were noticeable cavities in the bodies of the cars. Handheld laser scanning is a time-efficient method while UAS photogrammetry can be performed at a lower cost. In conclusion, it is not possible to arrive at an unambiguous conclusion with regards to which method that is best suited for documenting a traffic accident. The choice depends on the prevailing circumstances at the accident scene.

The usability of GNSS-positioning with smartphones has increased because of smartphones being a cost-effective alternative compared to more advanced receivers. Previous studies have achieved position uncertainty that varied between 3–20 m with different applications in smartphones. No studies have been found that evaluates the positional uncertainty in data collected with the Strava application. Therefore, this study aims to evaluate positional uncertainty in Strava for two different smartphones being compared in two terrain types, forested and open terrain. In the study, the GNSS receiver Trimble R12 is used to measure reference data as it can achieve lower uncertainty than smartphones. The two tested smartphones (iPhone 8 and iPhone 12 Pro) are mounted on the bicycle handlebar from where the measurement is performed. The position uncertainty is evaluated by calculating the root mean square deviation (RMS). The result of the study shows that the positional uncertainty in the iPhone 12 Pro is lower compared to the iPhone 8, regardless of terrain and speed. For all measurements, the iPhone 12 Pro achieves a total root mean square deviation of 1.5 m, while the iPhone 8 achieves 7.5 m. Factors that may have affected the uncertainty in measurements are satellite geometry, variations in the ionosphere and troposphere and errors during measurement. The iPhone 8 should not be used for collecting data for new trails due to the high deviations. The iPhone 12 Pro is considered credible with low deviations throughout where the positional uncertainty between open and forested terrain differs by 0.2 m. Furthermore, it would be of interest to investigate how the iPhone 12 Pro relates to newer hardware. / Trots att positioneringsosäkerheten är högre i smartphones än i avancerade mottagare har användbarheten ökat för GNSS-positionering med smartphones till följd av det kostnadseffektiva alternativ som det innebär. Intresset för att skapa ledsystem med data insamlade med livetracking i smartphones har ökat. Uppnådd lägesosäkerhet i tidigare studier har varierat mellan 3–20 m med olika applikationer i smartphones. Det har inte påträffats studier som utvärderat lägesosäkerheten i data insamlade med applikationen Strava och därför är det av intresse att genomföra en sådan. Syftet med studien var att undersöka vilken lägesosäkerhet som kan uppnås i terräng via livetracking med smartphones med applikationen Strava. För att uppnå syftet undersöktes lägesosäkerheten med två smartphones i skogbevuxen och öppen terräng. I studien genomfördes också en begränsad undersökning av hastighetens inverkan på lägesosäkerheten i öppen terräng. För att kunna förlita sig på data behöver lägesosäkerheten i smartphones kontrolleras mot referensdata inmätt med en metod som kan erhålla lägre osäkerhet. I studien användes GNSS-mottagaren Trimble R12 för inmätning av referensdata. En iPhone 8 och en iPhone 12 Pro monterades på ett cykelstyre där mätning med Strava genomfördes cyklandes på 100 m långa sträckor i öppen och skogbevuxen terräng. Lägesosäkerheten utvärderades genom att beräkna kvadratisk medelavvikelse (RMS).  Resultatet visar att lägesosäkerheten med iPhone 12 Pro är lägre i jämförelse med iPhone 8 oberoende av terräng och hastighet. För samtliga mätningar uppnår iPhone 12 Pro en total kvadratisk medelavvikelse på 1,5 m medan iPhone 8 uppnår 7,5 m. Faktorer som kan ha påverkat osäkerheten i mätningar är satellitgeometri, variationer i jonosfären och troposfären samt fel under mätning. iPhone 8 bör inte användas för insamling av data till nya leder på grund av de höga avvikelserna. iPhone 12 Pro anses trovärdig med genomgående låga avvikelser, där lägesosäkerheten mellan öppen och skogbevuxen terräng skiljer 0,2 m. Vidare skulle det vara av intresse att undersöka hur iPhone 12 Pro förhåller sig till nyare hårdvara.