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Output's histograms - How to interpret each index?

Good afternoon,

I’d like to know more about the meaning of each index through their respective histograms.
I’m using a Micasense Altum camera so I have few different outputs available to me. Since most of those indexes are related to vegetation’s health, where the minimum values mean unhealthy vegetation, soil, roads, etc and the maximum values mean healthy vegetation.
My question is: how about the Thermal output? It usually gives me a minimum value of 29000 and a maximum value of 30000. Does the histogram range from the minimum temperature to the maximum temperature captured in said Thermal output?
And if yes, how is this associated with ºC/ºF temperatures?

In another note, NDVI for example ranges from -1 to 1 but most of my generated NDVI’s range between other values, for example, -0.15 to 0.15. I assume fields tend to use the minimum and maximum registered values on each project, instead of using default values, in this case, -1 to 1 for NDVI.

Any feedback regarding these aspects would be highly appreciated!

Best regards,
James

Hi James,

The thermal pixel values need to converted to degree C with the formula Thermal_ir=(lwir/100)-273.15

The values will be between that range -1 to +1. Since -0.15-0.15 is within that range it is correct. The range will differ for each project with min-max NDVI values as the range, as you mentioned.