The rapid increase of the Philippine population and its economy has spurred an urban sprawl in various cities and towns across the country. The rise of building structures used for residential, commercial, medical, and industrial purposes have entailed land use conversion which presents a challenge for government monitoring. Comprehensive mapping and inventory of building structures for the purpose of urban planning, disaster risk management, and other applications have been lacking due to the limited manpower and financial resources of the national and local governments. A platform for Volunteered Geographic Information (VGI) data collection is thus useful when the government machinery cannot keep up with the expanse of the urban sprawl. Furthermore, geospatial databases populated by VGI would aid decision-makers in the formulation of government socio-economic policies, urban planning, and disaster management plans including loss estimation in the event of disasters.

This study incorporates both web-based tools and android mobile application in creating a framework that can be used in geospatial mapping of building structures. Using available Digital Surface Model (DSM) which is derived from LiDAR data and orthophotos, building outlines are manually extracted to create a geospatial database of the building structures in the flood-prone zones of Western Visayas, Philippines. Each building outline is represented by a polygon, referred here as digitized building. The geographic coordinates of the vertices of the digitized buildings are extracted and uploaded to the database server so that it will be readily available for download in web-based and mobile application. These geographic coordinates when downloaded are linked to create a digitized building which is overlaid to Google Map. The database framework includes building attributes such as building materials, building height, and number of floors which are essential information in disaster management. The framework uses unified structures across web and mobile which incorporates the application of VGI. Building structures are mapped and attributed by mobile device users who act as efficient local contributors.