ABSTRACT
Both fixed-wing and multi-rotor platforms are increasingly being identified as potentially useful airborne platforms for a range of professional environmental remote sensing applications, including both expensive high-end specialist solutions and lower-cost, off-the-shelf commercial options. Small unmanned aerial vehicles (UAVs) are ideal for applications where aerial coverage requirements are small, flying experience and expertise is limited, and the operating budget is usually relatively small. With advances in battery technology, navigational controls, and payload capacities, many of the smaller UAVs are now capable of utilising several different sensors to collect photographic data; video footage; multispectral, thermal, and hyperspectral imagery; as well as light detection and ranging (LiDAR). With the aid of specialist digital image processing and soft-copy photogrammetry software, aerial data and imagery can be processed into a number of different products including ortho-photos, mosaics, and Digital Elevation Models (DEMs) and analysed to generate useful information for input to a Geographic Information System (GIS). Aerial photography and video imagery have been acquired using small aerial platforms for over 30 years. Small-scale radio-controlled (RC) model aircraft and helicopters, using small 35 mm single-lens reflex (SLR) and video cameras, have all been used to acquire panchromatic, colour, colour infrared (CIR), and multispectral aerial photography for a wide range of environmental applications. This chapter begins by examining the history of small-scale aerial (SSA) platforms for aerial image acquisition as the context for the current growth in popularity of UAVs, the associated technologies, and the range of small-scale sensors (e.g. GoPro Hero cameras) currently available for environmental monitoring, mapping, and modelling applications, together with image processing, analysis, and information extraction and soft-copy photogrammetry software such as Pix4D, Agisoft, and AirPhotoSE. The past and present advantages and disadvantages of small aerial platforms are also considered, together with some of the emerging technologies and recent developments.
