Recent disasters, such as the 2010 Haiti earthquake, have drawn attention to the potential role of citizens as active information producers. By using location-aware devices such as smartphones to collect geographic information in the form of geo-tagged text, photos, or videos, and sharing this information through online social media, such as Twitter, citizens create Volunteered Geographic Information (VGI). To effectively use this information for disaster management, we developed a VGI framework for the discovery of VGI. This framework consists of four components: (i) a VGI brokering module to provide a standard service interface to retrieve VGI from multiple resources based on spatial, temporal, and semantic parameters; (ii) a VGI quality control component, which employs semantic filtering and cross-referencing techniques to evaluate VGI; (iii) a VGI publisher module, which uses a service-based delivery mechanism to disseminate VGI, and (iv) a VGI discovery component to locate, browse, and query metadata about available VGI datasets. In a case study we employed a FOSS (Free and Open Source Software) strategy, open standards/specifications, and free/open data to show the utility of the framework. We demonstrate that the framework can facilitate data discovery for disaster management. The addition of quality metrics and a single aggregated source of relevant crisis VGI will allow users to make informed policy choices that could save lives, meet basic humanitarian needs earlier, and perhaps limit environmental and economic damage.

The value of real estate is an important matter for municipal authorities, since property tax is one of their main budget sources. Its estimation tends to be a complex process, owing to the diversity of factors affecting it. One of those factors is property location, which embraces the geographic relationship between the property and the surrounding local amenities. Hedonic modelling is frequently applied to estimate the value of a property; to consider the influence of property location within such models, the region under analysis is usually divided into homogeneous areas. This division can introduce a bias (a particular vision) related to the modifiable areal unit problem. Our intent in this paper is to apply data mining techniques to address a possible valuer bias, a particular valuer’s vision, in the current City of Calgary assessment model. Employing the decision tree technique, one locational attribute (Sub-Neighbourhood) was represented by the (x, y) coordinates of the properties, with approximately 96% correct classification with respect to their City of Calgary sub-neighbourhood designation. By adopting the regression tree technique, we show that it is possible to explain approximately 73% variability of the Sale Price attribute, using only the attribute Sub-Neighbourhood or the (x, y) coordinates as input. In general, the results showed a consistent relationship between property value and location. Additionally, the sale price patterns of actual properties do not conform strictly to the politico-administrative units adopted by the city. Those patterns usually cross the unit boundaries limits or are mixed inside a unit. Our results suggest that using a property’s spatial coordinates, instead of political-administrative subdivisions, to express its location, would lead to more accurate results and not incur the possibility of bias.

In the wake of the Mabo decision from Australia and the Delgamuukw decision from Canada, it is clear that Aboriginal Title to land can only be lost through cession by treaty, abandonment, conquest, or legitimate legislation of the Crown. What is less clear is the effect that legitimate Crown Grants and Certificates of Title (accompanied by parcel boundary surveys) have on claims to aboriginal servitudes. Such servitudes represent non-territorial aboriginal title, and are akin to easements in statute law. Some of the tension over title to, and use of land can be defused by using fuzzy theory to define zones of overlapping rights in land. Such a methodology is similar to the continuing use of general boundaries in which a feature (sometimes ambulatory) defines the spatial extent of a parcel, allows sites of spiritual significance (sometimes used only seasonally) to be defined, and has application to New Zealand and Australia. Waahi Tapu could be thus defined (if not demarcated), thus according with the principle of the silent files used by the Ngai Tahu in Canterbury. Gustafsen Lake, British Columbia, Canada is used as a case study. The context is that the Shuswap peoples have never ceded their land by way of treaty to the Crown. The tragedy is that when Percy Rossette and a score of his friends used the land for a Sundance ceremony during the summer of 1995, the police blew up their truck, shot and wounded a woman, and killed a dog. The explanation can be traced to an 1892 Crown Grant, to the present use of the site for ranching, to the natives fencing an area larger than the Sundance site, to persistent opposition by most Shuswap peoples to ceding their land, to a treaty claims process intent on extinguishing aboriginal title, to a brilliant if quixotic lawyer, and to politicians keen to uphold the rule of law.