The second topic in our solar series explores SUMO’s Photogrammetry Surveys.
As well as capturing topographic data, these surveys can be used to provide accurate models for landscape analysis and archaeological interpretations.
In addition to capturing topographic data (covered in our previous blog), UAS photogrammetry produces highly accurate Digital Elevation Models (DEMs) and orthorectified mapping of large areas, which can prove invaluable in designing the layout of a solar farm.
The UAS photogrammetry method consists of taking aerial photographs in a grid pattern over a survey area and capturing vertical images from altitudes of between 50m and 120m, which enables the coverage of large areas in relatively short timeframes. The resulting images are processed to produce a point cloud, DEMs (Digital Elevation Models) and an orthophotograph.
Textured Digital Elevation Models, like the example below, can help planners and designers to understand and visualise the landscape.
Above: Digital Elevation Models (DEM) of a 300 hectare landscape survey.
The DEMs can then be processed using GIS software to produce various models (including hill shading or terrain flattening to isolate the topography), which may aid the interpretation of the landscape and the configuration of the solar panels to be installed.
Above: Greyscale hillshade produced from a DEM.
Above: Terrain flattening to highlight the microtopography.
The DEM can also be analysed using GIS to tease out micro-topographic features which can be discussed in an interpretive report.
In addition, where a multispectral survey has been conducted, different vegetation indices are applied using raster transformations, such as NDVI (Normalized Difference Vegetation Index) which can highlight the possible presence of other subsurface features (including archaeology), which might impact on the installation and layout of the solar panel arrays.
Above: Example of an archaeological interpretation from a SUMO report.
The design and installation of a renewable energy site is a complex and costly exercise, so it pays to maximise the potential output of the site through a careful analysis of the site at the design stage. In these circumstances, the use of a SUMO Photogrammetry Survey can be invaluable in providing accurate data across large areas quickly and efficiently.