Billboard Measurements using Oblique UAV Images for Improved Revenue Collection

Abstract

Nairobi City County is one of the smallest yet most populous of the 47 counties in Kenya. Being one of the cornerstone counties of the economy of Kenya, its limited resources must be managed properly to guarantee sustainability. One of the major revenue streams of the county is Outdoor Advertising which currently rakes in an annual average of KS. 700 million against a potential of Ksh. 2 billion (Omulo, 2018). This means that revenue collection is not optimized and according to the county’s Annual Development Plan 2020-2021, the county seeks to employ technology and expertise, especially from the private sector, to improve its revenue collection and compliance to by-laws. This study therefore employs the use of Unmanned Aerial Vehicle (UAV) imagery and advanced Photogrammetric techniques to measure billboards for purposes of inventory keeping and monitoring. As was proven by the hypothesis, the process can be a cheaper and faster alternative to creating georeferenced 3D models, which have previously been a preserve of sophisticated and expensive methods like laser scanning. In the end, a 3D georeferenced render of the scenery was generated, with good planimetric and altimetry accuracies. Aerial oblique images were used to generate a dense point cloud by using an image matching algorithm that deduces the interior and exterior orientation parameters to reconstruct a georeferenced 3D model of the areas of interest. The model was then used to accurately measure billboard dimensions, which is the basis for advertising rates. With this data, more informed revenue projections can be made and even help keep an inventory of the number of billboards and their usage along every stretch of the road within the city.