Capturing reality – UAVs that see in 3D and more
UAVs bring a whole new level to what is possible when capturing data and imagery, with elevation modelling being just one really powerful application of UAV surveys. It’s probably one of our most popular products at Remote Aerial Surveys.
For example, 3D visualisations are just one aspect of elevation modelling that is becoming increasingly popular for marketing new and planned developments. The data captured by using a UAV mounted camera can produce 3D models that make a really engaging tool for communicating information about the landscape.
The wonders of photogrammetry
Usually elevation modelling is achieved through a process called photogrammetry. This process is essentially very similar to the way we use two eyes to judge distance. Photogrammetry works by finding the same point in different overlapping images, calculating height using the point’s relative location in each of the photos and additional factors such as flight and camera characteristics. Elevation modelling can be seen as the backbone for a wide variety of environmental monitoring projects, and from it you can derive a whole range of information such as some of the most common applications outlined below.
Understanding the landscape
Geomorphology and Terrain Analyses– in addition to the elevation model itself, some of the datasets which can be extracted from the model (such as terrain slope, aspect and ruggedness grids) are very useful for understanding and visualising the physical landscape. Flight plans can be programmed to repeat the same flight any number of times, allowing accurate quantifying of processes such as creep and landslides. This data can also be used to conduct volumetric surveys. Such surveys are typically used for purposes such as determining the volume of material stockpiles, dam and watercourse capacity, and remaining and used landfill space.
Identifying flood risks
Hydrology–UAV-derived data can be used to perform terrain-based hydrological analyses e.g. you can use high resolution elevation data to assess water flow direction and accumulation, ideal for things like flood and catchment management projects. Another popular application is the modelling of river channels, often with the purpose of creating detailed cross sections of the river banks.
Getting closer to reality with orthophotos
For mapping purposes elevation modelling is a crucial element in a process called orthorectification. This process removes any distortion in the photo caused by variations in the terrain and land cover, so that the entire image appears as if you are looking straight down at it (having also been corrected for lens distortions). This means that, for example, you’ll see the tops of things like trees and buildings, rather than their side surfaces. Once georeferenced (i.e. given a location in geographic space), orthophotos can be used in the same way that maps can be used, such as accurately measuring distances and areas. This makes them ideal tools for projects such as development planning and map verification and update.
Photorealistic aids for developers & planners
Elevation modelling has a wide range of potential uses across the planning and construction industry. From creating orthorectified photomaps (see above) to act as a base map for planning documents, to visualising proposed developments on a 3D ‘photorealistic’ model of the terrain, to capturing elevation photography and imagery to monitor construction progress – there are huge possibilities.
And there’s more to come…
Indeed this has been only a very quick skip through just a few of the things that are now possible with the latest UAV and imaging technology. I’ll be sure to post more updates as we hear of more great new applications.