VGI Data Research Articles

A Generic Spatial OLAP Model for Evaluating Natural Hazards in a Volunteered Geographic Information Context

Spatial data warehouses (SDW) and spatial OLAP (SOLAP) systems are well-known business intelligence technologies that aim to support a multidimensional and online analysis for a large volume of geo-referenced datasets. SOLAP systems are already used in the context of natural hazards for analyzing sensor data and experts' measurements. Recently, new data gathering tools coined as volunteered geographic information systems (VGI) have been adopted especially by non-expert users. Hence, (spatial) application development is facing a new challenge, which is the integration of expert-oriented data with citizen-provided data. In this paper, we propose a new generic spatio-multidimensional model based on the question/answer risk evaluation model that allows the integration of VGI data with classical SDW and SOLAP systems for the online analysis of natural hazards monitored by volunteers.

VGI and Reference Data Correspondence Based on Location‐Orientation Rotary Descriptor and Segment Matching

AbstractVolunteered geographic information (VGI) is spatial data that has been contributed by numerous volunteers in the form of user‐generated content. VGI provides the ability for non‐experts to collect and share geographic information. Comparison of a VGI dataset with a reference dataset in order to find data correspondence is a common process in some analyses of VGI data, such as quantitative analysis of its quality. This study addresses this case and presents an automated feature matching method for VGI linear data. The proposed method consists of two main steps. In the first step, a feature point matching method based on a novel descriptor, named Location‐Orientation Rotary Descriptor (LORD), is performed. The proposed LORD descriptor uses the location and orientation information of the linear data in a log polar structure and in a rotary manner. In the second step, a new segment matching strategy based on the buffered linear features is performed to reject the outliers of the previous step. The usefulness of the proposed method was demonstrated by applying it to the OpenStreetMap (OSM) dataset, as a VGI dataset, using an official reference dataset.

A BOTTOM-UP GEOSPTIAL DATA UPDATE MECHANISM FOR SPATIAL DATA INFRASTRUCTURE UPDATING

Abstract. Currently, the top-down spatial data update mechanism has made a big progress and it is wildly applied in many SDI (spatial data infrastructure). However, this mechanism still has some issues. For example, the update schedule is limited by the professional department’s project, usually which is too long for the end-user; the data form collection to public cost too much time and energy for professional department; the details of geospatial information does not provide sufficient attribute, etc. Thus, how to deal with the problems has become the effective shortcut. Emerging Internet technology, 3S technique and geographic information knowledge which is popular in the public promote the booming development of geoscience in volunteered geospatial information. Volunteered geospatial information is the current "hotspot", which attracts many researchers to study its data quality and credibility, accuracy, sustainability, social benefit, application and so on. In addition to this, a few scholars also pay attention to the value of VGI to support the SDI updating. And on that basis, this paper presents a bottom-up update mechanism form VGI to SDI, which includes the processes of match homonymous elements between VGI and SDI vector data , change data detection, SDI spatial database update and new data product publication to end-users. Then, the proposed updating cycle is deeply discussed about the feasibility of which can detect the changed elements in time and shorten the update period, provide more accurate geometry and attribute data for spatial data infrastructure and support update propagation.