What Can I Do With 8 Band Imagery?
The satellite imagery we provide is often ordered as "natural colour" with red, green, and blue spectral bands to simply provide a base layer for mapping in areas where aircraft sourced orthophoto is not available or not current enough. For more sophisticated applications, multi-spectral imagery with 4 bands or 8 bands can be ordered to view imagery in "false colour".
Why do I want false colour?
False colour offers the chance to customize the display to better highlight differences between similar looking surface types, and perform more types of quantitative enhancements such as NDVI ((NIR - Red) / (NIR + Red)) to tease out the sites where plant productivity is higher or lower than nearby sites.
Visible light doesn't capture the full load of information available when electro-magnetic radiation reflects off objects on the ground. For example, a golf course and AstroTurf will look the same when comparing red, green, and blue spectral bands, however, they will look very different when infrared reflectance is compared.
|When comparing natural colour to colour infrared, the real grass of the baseball diamond strongly reflects infrared while the football field to the southeast is revealed to be artificial turf.|
What are the bands?
The 4-band imagery (near infra-red, red, green, blue) works well for simple CIR (colour infra-red ) applications. The additional bands in 8-band imagery allow a more detailed look at the reflectance. Comparing different sensors, the narrower the wavelength range for a band, the more specific the questions that can be answered. For example, a ground feature that falls in the green band in a Pleiades image could be blue, green, or yellow when viewed in a WorldView image.
|Spectral band ranges for our top selling satellite sensors.|
The Infrared band is broken out into red edge, NIR1 and NIR2. The three IR bands are significantly more sensitive to detecting subtle changes in plant health and growth states over the single IR band. In between the green and red bands, the addition of the yellow band can help differentiate plant species based on differences in yellow and orange carotenoid pigments which are usually masked by intensely green chlorophyll. On the blue end of the spectrum, the coastal blue band is only minimally absorbed by water and can therefore be used in bathymetry.
|When each band is visualized separately, lighter areas indicate the surface is reflecting the wavelength range in that band, dark areas indicate the surface is absorbing energy.|
How do I use 8 spectral bands with 3 RGB colour channels?
For WorldView2 and WorldView3, the most common visualizations are classic natural colour and false colour infrared, the additional bands also allow for enhanced false colour infrared and bathymetry.
With 8 band imagery, there are 512 3-band combinations to choose from! Land use classifications can be tailored to highlight more specific surface types based on narrow band ranges. For example, using the coastal band can help differentiate between deep water, sediment, and mud. Wider spectral bands would aggregate these nuances into a water class, or not water class. Here's a few more examples from around Halifax featuring different surface type enhancements.
How do I get 8 band satellite imagery for my site?
Contact First Base Solutions and send us a file to delineate your area of interest and the time frame you're looking for. We can undertake a search of various satellite archives or arrange tasking to capture new imagery.
Related: Ordering Planet Satellite Overview Satellite imagery from Planet is ideal for both visual and analytical uses. The agile approach to aerospace allows the entire earth to be captured every single day with a turnaround time of just a few hours...