By comparing it with other bands, we get indexes like NDVI, which let us measure plant health more precisely than if we only looked at visible greenness. This part of the spectrum is especially important for ecology because healthy plants reflect it – the water in their leaves scatters the wavelengths back into the sky. Like most urban areas, the colors of the city average out to light gray at this scale.īand 5 measures the near infrared, or NIR. Part of the western LA area, from agricultural land near Oxnard in the west to Hollywood and downtown in the east. But while we’re revisiting them, let’s take a reference section of Los Angeles, with a range of different land uses, to compare against other bands: Most plants produce surface wax (for example, the frosty coating on fresh plums) as they grow, to reflect harmful ultraviolet light away.īands 2, 3, and 4 are visible blue, green, and red. The ocean and living plants reflect more deep blue-violet hues. By itself, its output looks a lot like Band 2 (normal blue)’s, but if we contrast them and highlight areas with more deep blue, we can see differences:īand 1 minus Band 2. It’s also called the coastal/aerosol band, after its two main uses: imaging shallow water, and tracking fine particles like dust and smoke. That part of the spectrum is hard to collect with enough sensitivity to be useful, and Band 1 is the only instrument of its kind producing open data at this resolution – one of many things that make this satellite special. Just as we see a lot of hazy blue when we look up at space on a sunny day, Landsat 8 sees the sky below it when it looks down at us through the same air. This is one reason why very distant things (like mountains on the horizon) appear blueish, and why the sky is blue. Blue light is hard to collect from space because it’s scattered easily by tiny bits of dust and water in the air, and even by air molecules themselves.
To understand the value of all the bands, let’s look at them each in turn: The Bandsīand 1 senses deep blues and violets. The true-color view from Landsat is less than half of what it sees. Of its 11 bands, only those in the very shortest wavelengths (bands 1–4 and 8) sense visible light – all the others are in parts of the spectrum that we can’t see.
#RIDGE ROCK MULTISPEC FULL#
Have a look at the full list of Landsat 8’s bands: Band Number Landsat 8 view of the Los Angeles area, May 13th, 2013. Landsat numbers its red, green, and blue sensors as 4, 3, and 2, so when we combine them we get a true-color image such as this one:
Each range is called a band, and Landsat 8 has 11 bands. Landsat 8 measures different ranges of frequencies along the electromagnetic spectrum – a color, although not necessarily a color visible to the human eye.
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