What is false-colour processing?
While our eyes only detect a fraction of all light available, satellite sensors can actually capture – and send back – much more information. Furthermore, this information is relayed back to us in a format quite different from the photographs we are used to. For each band, satellites capture the spectral reflectance of the area within a specific narrow band of the light spectrum.
True-colour composite images use the red, green, and blue bands gathered by satellites to mimic the range of vision for the human eye, showing us images closer to what we would expect to see in a normal photograph.
Satellites also capture information in the non-visible part of the light spectrum. Different features: rock, bare soil, vegetation, burned ground, snow, sediment-rich water, etc. all have different reflectance properties in each band. This a called a 'spectral signature'.
Additionally, to better discriminate between features and highlight changes in time, mathematical models can be applied to the data to produce a new kind of processed image. These are referred to as indexes.
When should I use false-colour urban?
False-colour urban processed images are created using the following bands : Short-wave infrared 1 (SWIR1), short-wave infrared 2 (SWIR2), and red. In the processed images, SWIR 2 will be colorized red, SWIR 1 will be colorized green, and the red band will be colorized blue.
Tracking urban sprawl and flood risks
In false-colour urban images, urban areas will now appear in purple, which is useful to examine urban environment density. Water will also appear very dark in this combination, due to high absorption of SWIR and red light in water bodies, which makes coastlines and flood extents very clear.
How to obtain false-colour urban data using EarthCache
Note: If you do not have an account, you can sign up for one here.
To obtain a true-colour image using EarthCache, simply select False-colour infrared processing as an output when creating or editing a pipeline through the dashboard.
To obtain a true-colour image using code, you can create or edit a pipeline using the following parameters:
False-colour urban ID