The choice of imaging platform is critical to the level of detail that you can map, the total coverage and imaging timing needs
The remote sensing platforms discussed include satellite, manned aircraft and UAV. Each of these platforms have different strengths and weaknesses for remote sensing, but together they offer a wide range of complementary options for designing an effective remote sensing programme.
A key initial consideration relates to the level of surface detail that needs to be detected, defined as the spatial resolution. UAV can be used to detect the condition of pipelines, for example, which would not be possible from satellites. On the other hand, satellites can be used to map large areas such as open ocean, forests or water catchments which would be impractical for UAV. This concept is illustrated below.
Beyond the need to match the platform to the need for suitable coverage and spatial resolution, there are several other important platform considerations as follows:
- Satellites are very useful for ensuring measurement consistency, in particular over long time periods, which is useful for the detection of subtle changes over time. With some datasets going back to the 1980s, there are also opportunities to assess historic events and variability.
- Some types of aircraft are particularly suitable for flexible flight planning, for example in order to survey an intricate coastline, or to image from beneath the cloud layer. Satellites are inflexible in this regard.
- Satellites are able to image a location independently of the political or security situation on the ground, as well as outside the range of airspace and other terrestrial regulations. This provides more observational reliability, while at the same time avoiding the need to place personnel in potential danger.
Some key characteristics of the different platforms are shown below.
It is worth pointing out that some platforms are owned by public entities and their data is make publically available as a result, including from the National Aeronautics and Space Agency (NASA) and the European Union (operated by the European Space Agency, ESA). These include the Landsat and Sentinel satellites. These and other commercial satellites are tabulated in Appendix A (optical satellites) and Appendix B (radar satellites).