Evaluation of the quality of the Voluntary Geographic Information for the road network in Bogotá D.C

The production of Voluntary Geographic Information has been growing considerably and continues to be an active area of research. However, the lack of knowledge about the quality of information generated on a voluntary and participatory basis raises challenges and questions about its use. In the review carried out for the Colombian case, no studies related to the subject were identified; consequently, this study is presented on the evaluation of the quality of this type of information on the road network of Bogotá with respect to completeness, positional accuracy and thematic accuracy. This evaluation was carried out by means of a semi-automatic process that uses a mobile buffer and the centroid of the roads to make the corresponding comparisons between two data sources. The results found reveal that the method used allowed to compare up to 85.0% of the data, and that the OpenStreetMap mesh has a completeness of 85.4%, over the entire area of Bogotá. A positional accuracy of 3.98 m and a thematic accuracy related to the percentage of error in the attributes: Road hierarchy, direction of flow and road naming of 35.8%, 15.0% and 34.6% respectively. The quality evaluated through completeness, positional and thematic accuracy in synergistic terms is deficient with respect to the minimum quality levels established in the standard data model, however, the evaluation for each of the attributes shows an acceptable quality in terms of completeness and thematic accuracy

Modeling and improving Spatial Data Infrastructure (SDI)

Spatial Data Infrastructure (SDI) development is widely known to be a challenging process owing to its complex and dynamic nature. Although great effort has been made to conceptually explain the complexity and dynamics of SDIs, few studies thus far have actually modeled these complexities. In fact, better modeling of SDI complexities will lead to more reliable plans for its development. A state-of-the-art simulation model of SDI development, hereafter referred to as SMSDI, was created by using the system dynamics (SD) technique. The SMSDI enables policy-makers to test various investment scenarios in different aspects of SDI and helps them to determine the optimum policy for further development of an SDI. This thesis begins with adaption of the SMSDI to a new case study in Tanzania by using the community of participant concept, and further development of the model is performed by using fuzzy logic. It is argued that the techniques and models proposed in this part of the study enable SDI planning to be conducted in a more reliable manner, which facilitates receiving the support of stakeholders for the development of SDI.Developing a collaborative platform such as SDI would highlight the differences among stakeholders including the heterogeneous data they produce and share. This makes the reuse of spatial data difficult mainly because the shared data need to be integrated with other datasets and used in applications that differ from those originally produced for. The integration of authoritative data and Volunteered Geographic Information (VGI), which has a lower level structure and production standards, is a new, challenging area. The second part of this study focuses on proposing techniques to improve the matching and integration of spatial datasets. It is shown that the proposed solutions, which are based on pattern recognition and ontology, can considerably improve the integration of spatial data in SDIs and enable the reuse or multipurpose usage of available data resources

Geo-spatial Information Science Matching authority and VGI road networks using an extended node-based matching algorithm Matching authority and VGI road networks using an extended node-based matching algorithm

The amount of volunteered geographic information (VGI) has increased over the past decade, and several studies have been conducted to evaluate the quality of VGI data. In this study, we evaluate the completeness of the road network in the VGI data set OpenStreetMap (OSM). The evaluation is based on an accurate and efficient network-matching algorithm. The study begins with a comparison of the two main strategies for network matching: segment-based and node-based matching. The comparison shows that the result quality is comparable for the two strategies, but the node-based result is considerably more computationally efficient. Therefore, we improve the accuracy of node-based algorithm by handling topological relationships and detecting patterns of complicated network components. Finally, we conduct a case study on the extended node-based algorithm in which we match OSM to the Swedish National Road Database (NVDB) in Scania, Sweden. The case study reveals that OSM has a completeness of 87% in the urban areas and 69% in the rural areas of Scania. The accuracy of the matching process is approximately 95%. The conclusion is that the extended node-based algorithm is sufficiently accurate and efficient for conducting surveys of the quality of OSM and other VGI road data sets in large geographic regions

Joukkoistetun paikkatiedon laatu ja luotettavuus : Turun kaupunkiseudun pyöräilyverkosto OpenStreetMap-karttapalvelussa

Kansalaislähtöinen joukkoistettu paikkatieto on noussut varteenotettavaksi tietolähteeksi viranomaisten ja kaupallisen sektorin tuottaman auktoritatiivisen paikkatiedon rinnalle. Tuotantotavat poikkeavat toisistaan merkittävästi, mikä ilmenee joukkoistetun lopputuotteen laatuvaihteluna. Sitä aiheuttavat tavoitteiltaan ja taitotasoltaan kirjava kartoittajajoukko, tuotantoalustojen ominaisuudet ja avoin tuotantotapa, joka ei pakota vaatimustenmukaisuutta. Jotta joukkoistettua paikkatietoa voidaan luotettavasti hyödyntää auktoritatiivisessa yhteydessä, on ymmärrettävä sen laadullisia piirteitä. Niitä koskevaa kotimaista tutkimustietoa on vähän ja tiedon tarve on uusiutuva joukkoistetun paikkatiedon jatkuvasti päivittyessä ja rikastuessa teemoiltaan. Tutkielmassa tähän tarpeeseen pyrittiin vastaamaan vertaamalla joukkoistetun OpenStreetMap-karttapalvelun pyöräilyverkostotietoa Turun kaupungin ja sen ympäryskuntien ylläpitämän paikkatietoaineiston laatuvaatimuksiin. Laatu mitattiin ISO 19157:2013-standardin mukaisesti täydellisyyden, sijaintitarkkuuden ja topologisen eheyden laatuparametreille. Niitä määrällistettiin verkoston kokonaispituudella, keskimääräisellä etäisyydellä ja geometrisella yhdenmukaisuudella sekä kappalemääräisellä laskennalla. Alueellista vaihtelua arvioitiin visuaalisesti, keskihajonnalla ja tilastollisesti Anselinin paikallisella Moranin I -tunnusluvulla. Koska paikkatietoaineiston kokonaislaadun muodostaa kvantitatiivisen laadun lisäksi sopivuus käyttötarkoitukseen ja lisäksi kokonaislaadun molempien komponenttien yhteisvaikutus luotettavuuteen on aiemmassa tutkimuksessa jäänyt vähälle huomiolle, aineiston käytettävyyttä arvioitiin pyöräilyverkoston kartoitustarpeiden näkökulmasta laatuarvioon perustuen. Luotaava käytettävyysmittaus painotti pyöräilyverkoston kartoitustarpeille kriittisiä laatuparametreja käytettävyyttä ilmaisevassa aggregaatissa. Joukkoistetun paikkatiedon laatuun vaikuttavat tekijät ovat osin tilasidonnaisia. Tätä tutkittiin laatu- ja käytettävyysarvioiden tulosten alueellisen vaihtelun arviolla. OpenStreetMap-aineiston täydellisyyden ja sijaintitarkkuuden havaittiin olevan lähellä laatuvaatimusta ja osin täyttävän sen. Topologinen eheys osoittautui sen sijaan heikoksi. Käytettävyysmittaus puolestaan osoitti virheettömyyden vaatimuksen korostuvan sovellustarpeiden monimutkaistuessa. Sama aineisto voi soveltua hyvin yhteen käyttötarkoitukseen, mutta olla kelvoton toiseen. Kvantitatiivisen laadun ja käytettävyyden suuri alueellinen vaihtelu heikensi selvästi aineiston luotettavuutta. Vaikka laajoja yhtenäisiä hyvätasoisia alueita paikallisesti havaittiin, aineistotason luotettavuus oli välttävä. Tulokset osoittavat joukkoistetun paikkatiedon lunastavan osan sen hyödyntämiseen liittyvistä odotuksista, mutta sen luotettavuutta on vaikea ennakoida. Tämä viittaa laadunvarmistuksen jatkuvaan välttämättömyyteen sekä tarpeeseen asettaa laatumittauksen tavoitteet tapauskohtaisesti. Tällöin myös laatuparametreiltään tai alueellisesti osittain heikkolaatuista aineistoa voidaan käyttää sovelluskohteiden niin salliessa ja joukkoistetun paikkatiedon temaattisesta moninaisuudesta päästään erityyppisissä sovellusyhteyksissä hyötymään.Citizen-sourced volunteered geographic information (VGI) has emerged as a significant data source alongside authoritative spatial data produced by governmental agencies and the commercial sector. The modes of production differ substantially, resulting in variable quality in the crowdsourced final product. This variability stems from a diverse group of mappers in terms of objectives and skill levels, platform attributes, and an open production method that does not enforce conformity to standards. To reliably utilize crowdsourced spatial data in authoritative contexts, one must comprehend its quality attributes. There's a paucity of domestic research on this topic, and the need for information is recurrent, with VGI continually updating and diversifying in themes. This study aimed to address this gap by comparing the cycling network data from the crowdsourced OpenStreetMap service to the quality standards of spatial datasets maintained by the city of Turku and its surrounding municipalities. Quality was assessed based on the ISO 19157:2013 standard, focusing on completeness, positional accuracy, and topological integrity quality parameters. These were quantified by the total network length, average distance, geometric consistency, and count-based calculations. The regional variability was assessed both visually and statistically, using standard deviation and Anselin's local Moran's I index. Given that the overall quality of spatial datasets is not only defined by quantitative quality but also its suitability for intended use, and considering previous research has often overlooked the combined impact of these components on reliability, the usability of the dataset was evaluated from the perspective of cycling network mapping needs based on the quality assessment. This exploratory usability assessment emphasized quality parameters critical to cycling network mapping in an aggregate indicating usability. Factors influencing the quality of crowdsourced spatial data are partly location dependent. This was examined by analyzing the regional variability in the results of quality and usability assessments. The completeness and positional accuracy of the OpenStreetMap dataset were found to be close to the quality requirements and in some cases meeting them. However, topological integrity was notably weak. The usability assessment indicated an increased emphasis on the requirement for accuracy as application needs become more complex. The same dataset might be well-suited for one purpose but unsuitable for another. The significant regional variability in quantitative quality and usability markedly reduced the dataset's reliability. Even though extensive, consistently high-quality areas were observed locally, the dataset's overall reliability was found to be subpar. The results suggest that crowdsourced spatial data meets some of the expectations related to its utilization but remains a volatile data source in terms of reliability. This underscores the continuous necessity for quality assurance and the need to set quality assessment objectives on a case-by-case basis. This approach allows for the use of datasets that may be subpar in quality parameters or regional attributes, given the application permits, capitalizing on the thematic diversity of crowdsourced spatial data in various application contexts

Evaluación de la calidad de la información geográfica voluntaria mediante un enfoque de análisis multivariado - caso de estudio malla vial Bogotá-Colombia

El aumento en la producción de información geográfica voluntaria (VGI) ha venido creciendo considerablemente y se han realizado diversos estudios al respecto. Sin embargo, el desconocimiento de la calidad de la información generada en forma voluntaria y participativa, plantea retos y cuestionamientos sobre el uso de este tipo de información. Este trabajo tiene como objetivo realizar un análisis de la calidad de la información geográfica voluntaria (VGI) desde una perspectiva multivariada. Para ello se compararán los datos colectados a través de la plataforma Open Street Map (OSM) para el año 2017, respecto a la malla vial de Bogotá-Colombia, proveniente esta de una fuente oficial (Infraestructura de datos Espaciales de Bogotá catastro Distrital IDECA). En la revisión efectuada para el caso colombiano no se identificaron estudios relacionados con el tema; en consecuencia, se evaluó la calidad VGI de la malla vial de Bogotá bajo un enfoque multivariado, usando las medidas de completitud, exactitud posicional y exactitud temática. Esta evaluación se realizó por medio de un proceso semiautomático que usa un buffer móvil y el centroide de las vías para realizar las comparaciones correspondientes entre dos fuentes de datos. Los resultados encontrados revelan que el método empleado permitió comparar hasta el 85% de los datos, además se calculó que la malla OSM (Open Street Maps) tiene una completitud del 85.42%, sobre toda el área de Bogotá. Una exactitud posicional de 3.98 m y en general una calidad VGI deficiente, pues el porcentaje de error encontrado fue de aproximadamente 60.3%. Se concluyó que los datos VGI gozan de una completitud aceptable, una exactitud posicional óptima y una exactitud temática deficiente.Abstract: The increase in the production of voluntary geographic information (VGI) has been growing considerably and many studies have focused on studying this phenomenon. The problem to use this type of information it's related specifically in the ignorance of its quality and as in Colombia there are still no studies related to the subject. In this paper, the VGI quality of the Bogotá road network was evaluated using completeness, positional accuracy and thematic accuracy. This evaluation was made through a semi-automatic process that uses a mobile buffer and the centroid of the lines to perform the corresponding comparisons between two data sources. The results revealed that the method used could match 85% of the data, and it was calculated that OSM has a completeness of 85.42%, over the entire area of Bogotá. A positional accuracy of 3.97 m and generally, a poor VGI quality : Because the percentage of mistake found was over 60.3%, It was concluded that VGI data enjoy acceptable completeness, optimal positional accuracy and poor thematic accuracy.Maestrí