Identification of Illegal Buildings Using LiDAR Data

Abstract

In developing countries, urbanization is rapidly growing. To manage such urbanization, identifying and tracking building construction to keep it up to date in all dimensions is the essential and challenging job of the government. The objective of this research work is to find the individual building height and identify the illegal buildings in the selected area located in the Godavari municipality of Kailali district, Nepal.  For this research work, the latest airborne LiDAR and cadastral datasets were acquired from the Survey Department. It reduces the manual field survey effort, gives accurate results, and minimizes interference from the external environment. One of the most important dimensions of LiDAR data is the z-axis value, which gives the accurate height of the object. A normalized digital surface model is calculated with the help of DTM and DSM. By utilizing the normalized Digital Surface Model (nDSM), precise building heights were extracted, which facilitated the estimation of the total number of floors per structure. This derived floor count data was then cross-referenced with municipal records to identify discrepancies. By adopting this process, the municipality can systematically verify building heights and automate floor-area and floor height calculations to ensure alignment with local building codes, and perform more accurate property tax assessments.