Georeferencing old maps: a polynomial-based approach for Como historical cadastres

Recent developments in digital technologies have opened new and previously unimagined possibilities for the exploitation of cartographic heritage. In particular, georeferencing converts them from pure archival documents to real geographic data. This study investigates the issue of georeferencing the historical maps which are currently preserved at the State Archive of Como. These maps, about 15000 at the scale of 1:2000, belong to different cadastral series: the Theresian Cadastre (XVIII century), the Lombardo-Veneto Cadastre (mid-XIX century) and the New Lands Cadastre (1905). Georeferenced maps should then be inserted in the Internet GIS system, developed within the Web C.A.R.T.E. project, for an interactive 2D- and 3D consultation. Due to the peculiar nature of maps, which are divided in several adjacent cadastral sheets for each municipality, a preliminary mosaicking of these sheets was performed. Using the digital cartography of current municipalities, Ground Control Points and Check Points were collimated on the historical maps. A polynomial transformation was chosen to georeference the maps. An ad hoc-built procedure based on statistical evaluation of GCPs and CPs residuals was implemented, in order to determine the optimal polynomial order to be used. Evaluation of georeferencing results was performed both qualitatively and quantitatively. The obtained accuracy is much higher, as the territories covered by the maps are smaller and more densely-built. The methodology is automated and can be proposed as a reference for georeferencing maps of comparable characteristics. Historical maps can thus be continuously navigated into a georeferenced framework and compared with current cartography. This clears the way for the usage of historical maps in a wide range of applications, such as territorial planning, urban and landscape changes analysis and archaeological research

Web services and historical cadastral maps: the first step in the implementation of the Web C.A.R.T.E. system

In the State Archive of Como, Northern Italy, about 15000 historical cadastral maps corresponding to 246 current municipalities of Como and Lecco districts are preserved. These maps belong to different cadastral productions: the Theresian cadastre, promoted in 1718 by Emperor Carl VI and come into force in 1760 during the reign of Maria Teresa; the Lombardo- Veneto cadastre, started in 1854 and completed, with continuous updates during the time, at the end of the century; and finally some maps of 1905 belonging to the New Lands Cadastre, the first national geometric cadastre after Italian unification of 1861. Maps have not only a considerable artistic value but mostly a cultural and historical one, since they constitute a great source to derive an accurate representation of the territory and its evolutions. For these reasons, the old maps represent nowadays a valuable instrument for historians, scholars and professionals working both in the historical research field and in the urban and territorial planning. The project Web C.A.R.T.E. (Web Catalogo e Archivio delle Rappresentazioni del Territorio e delle sue Evoluzioni), sponsored by the Fondazione Provinciale della Comunità Comasca Onlus, has been started to enhance the immense cartographic heritage of the State Archive of Como using the most recent technologies of map processing and web services. After the maps digitization step, performed by the State Archive in agreement with the interested municipalities, a georeferencing and warping procedure is needed to place the cadastral maps in the actual Italian reference system, thus making it possible to overlap them to the current cartography. Being the most of the maps divided in sheets, that have been surveyed and drawn independently from each other, the preliminary step has been to combine the sheets in a single map by applying to them a roto- translation with a scale variation. The georeferencing of unified maps has then been performed and tested in different software and GIS packages to determine the optimal solution. Finally PCI Geomatica OrthoEngine has been chosen, thanks to its variety of implemented mathematical models and to the possibility of inserting not only Ground Control Points (points of known coordinates, both in the actual cartography and in the historical map, that are used to compute the mathematical model) but also Check Points, points with known coordinates that are not included in the transformation and can therefore be used to check the model accuracy. The residuals of the transformation have then been used to determine the best georeferencing model for each cadastral map, confirming the choice with statistical techniques. The following step has been the documentation of georeference d maps in terms of metadata, a series of information needed to precisely identify the data and get information about their content, accuracy, accessibility and usage constrains. Metadata schema are currently defined by national and international standards: at the Italian level, the CNIPA (Centro Nazionale per l’Informatica nella Pubblica Amministrazione) proposed in 2006 a standard which is in agreement with the European Directive INSPIRE and defines a common set of metadata related to all kinds of geographic information used by national Public Administrations. Metadata for the historical georeferenced maps have therefore been compiled according to the Italian standard; last step has been their publication on the Internet through GeoNetwork, an open source web geo-catalogue that allows users to immediately identify a data and derive (from its metadata) information about language, spatial extent, reference system, responsible person or agency, accessibility, possible limitations on the usage, data origin and production process, and other features. Digitized and georeferenced maps, accompanied by their metadata, can finally be visualized and navigated online through the implementation of a dedicated webGIS. The realization of this viewing service implies the usage of software and tools both from the server and the client-side. Applying FOSS (Free and Open Source Software) solutions, a system with interactive functionalities and able to manage large raster maps has been developed. The entire service is currently in a test phase to verify its fulfilment of specific requests and needs expressed by experts from the State Archive; for this reason it may be possible that new and improved solutions will be introduced in the future

Participatory GIS: experimentations for a 3D social virtual globe

The dawn of GeoWeb 2.0, the geographic extension of Web 2.0, has opened new possibilities in terms of online dissemination and sharing of geospatial contents, thus laying the foundations for a fruitful development of Participatory GIS (PGIS). The purpose of the study is to investigate the extension of PGIS applications, which are quite mature in the traditional bi-dimensional framework, up to the third dimension. More in detail, the system should couple a powerful 3D visualization with an increase of public participation by means of a tool allowing data collecting from mobile devices (e.g. smartphones and tablets). The PGIS application, built using the open source NASA World Wind virtual globe, is focussed on the cultural and tourism heritage of Como city, located in Northern Italy. An authentication mechanism was implemented, which allows users to create and manage customized projects through cartographic mash-ups of Web Map Service (WMS) layers. Saved projects populate a catalogue which is available to the entire community. Together with historical maps and the current cartography of the city, the system is also able to manage geo-tagged multimedia data, which come from user field-surveys performed through mobile devices and report POIs (Points Of Interest). Each logged user can then contribute to POIs characterization by adding textual and multimedia information (e.g. images, audios and videos) directly on the globe. All in all, the resulting application allows users to create and share contributions as it usually happens on social platforms, additionally providing a realistic 3D representation enhancing the expressive power of data

MiniMapathon: mappare il mondo a 10 anni

Il presente articolo illustra il primo e più grande esperimento al mondo di MiniMapathon, ovvero un mapathon (editing collaborativo di mappe) a scopo umanitario realizzato con 250 studenti di quarta e quinta della scuola primaria. Vengono illustrate le motivazioni che hanno portato al MiniMapathon, i risultati didattici, i benefici in termini di conoscenze e di atteggiamento verso la geoinformatica e le potenzialità di questa particolare attività, indagate attraverso questionari agli studenti e interviste ai docenti delle classi coinvolte

Generating Up-to-Date and Detailed Land Use and Land Cover Maps Using OpenStreetMap and GlobeLand30

With the opening up of the Landsat archive, global high resolution land cover maps have begun to appear. However, they often have only a small number of high level land cover classes and they are static products, corresponding to a particular period of time, e.g., the GlobeLand30 (GL30) map for 2010. The OpenStreetMap (OSM), in contrast, consists of a very detailed, dynamically updated, spatial database of mapped features from around the world, but it suffers from incomplete coverage, and layers of overlapping features that are tagged in a variety of ways. However, it clearly has potential for land use and land cover (LULC) mapping. Thus the aim of this paper is to demonstrate how the OSM can be converted into a LULC map and how this OSM-derived LULC map can then be used to first update the GL30 with more recent information and secondly, enhance the information content of the classes. The technique is demonstrated on two study areas where there is availability of OSM data but in locations where authoritative data are lacking, i.e., Kathmandu, Nepal and Dar es Salaam, Tanzania. The GL30 and its updated and enhanced versions are independently validated using a stratified random sample so that the three maps can be compared. The results show that the updated version of GL30 improves in terms of overall accuracy since certain classes were not captured well in the original GL30 (e.g., water in Kathmandu and water/wetlands in Dar es Salaam). In contrast, the enhanced GL30, which contains more detailed urban classes, results in a drop in the overall accuracy, possibly due to the increased number of classes, but the advantages include the appearance of more detailed features, such as the road network, that becomes clearly visible

TOWARDS THE INTEGRATION OF AUTHORITATIVE AND OPENSTREETMAP GEOSPATIAL DATASETS IN SUPPORT OF THE EUROPEAN STRATEGY FOR DATA

Abstract. Digital transformation is at core of Europe's future and the importance of data is well highlighted by the recently published European strategy for data, which envisions the establishment of so-called European data spaces enabling seamless data flows across actors and sectors to ultimately boost the economy and generate innovation. Integrating datasets produced by multiple actors, including citizen-generated data, is a key objective of the strategy. This study focuses on OpenStreetMap (OSM), the most popular crowdsourced geographic information project, and is the first step towards an exploration of pros and cons of integrating its open-licensed data with authoritative geospatial datasets from European National Mapping Agencies. In contrast to previous work, which has only tested data integration at the local or regional level, an experiment was presented to integrate the national address dataset published by the National Land Survey (NLS) of Finland with the corresponding dataset from OSM. The process included the analysis of the two datasets, a mapping between their data models and a set of processing steps – performed using the open source QGIS software – to transform and finally combine their content. The resulting dataset confirms that, while addresses from the NLS are in general more complete across Finland, in some areas OSM addresses provide a higher detail and more up-to-date information to usefully complement the authoritative one. Whilst the analysis confirms that an integration between OSM and authoritative geospatial datasets is technically and semantically feasible, future work is needed to evaluate enablers and barriers that also exist at the legal and organisational level

Investigating the feasibility of geo-tagged photographs as sources of land cover input data

Geo-tagged photographs are used increasingly as a source of Volunteered Geographic Information (VGI), which could potentially be used for land use and land cover applications. The purpose of this paper is to analyze the feasibility of using this source of spatial information for three use cases related to land cover: Calibration, validation and verification. We first provide an inventory of the metadata that are collected with geo-tagged photographs and then consider what elements would be essential, desirable, or unnecessary for the aforementioned use cases. Geo-tagged photographs were then extracted from Flickr, Panoramio and Geograph for an area of London, UK, and classified based on their usefulness for land cover mapping including an analysis of the accompanying metadata. Finally, we discuss protocols for geo-tagged photographs for use of VGI in relation to land cover applications

Volunteered Geographic Information and OpenStreetMap: Experimentations and Perspectives

Volunteered Geographic Information (VGI) is the most successful term to mark the shift (happened almost a decade ago) according to which citizens, in addition to being data consumers, have also become precious providers of geographic information. The increasingly large volumes of datasets generated by VGI projects have attracted a huge academic interest in a number of topics, ranging from data quality assessment to data mining and data conflation, societal studies as well as ethical and privacy issues. The most popular VGI project, OpenStreetMap (OSM), which aims at the generation of a crowdsourced map of the world, can be nowadays considered as a research topic on its own. In the poster a wide range of the author's current research works on VGI and OSM is shown. These works partially derive from the author’s involvement in three (current or just ended) EU COST Actions: TD1202 "Mapping and the Citizen Sensor", IC1203 “ENERGIC”, and CA15212 “Citizen Science to promote creativity, scientific literacy, and innovation throughout Europe”