Value of every band

antonio.santos.rodri · December 18, 2022, 4:56pm

Hello,

I want to know the value of every color band.
I know that:

CoastalBlue=431 - 452nm
B=465 - 515
G1=513 - 549
G2=547 - 585
Y=600 - 620
R=650 - 680
RedEdege=697 - 713
NIR=845 - 885

But when I try to know the value of them it is not the same. Example:

evalscript = """
        //VERSION=3
        function setup() {
          return {
            input: [{
                bands: ["Green"],
                units: "DN"
            }],
            output: { 
                id: "default",
                bands: 1,
                sampleType: SampleType.FLOAT32
            }
          };
        }

       
        function evaluatePixel(sample) {
            var green =  sample.Green
            return [green];
        }

The result it isn’t between G1=513 - 549, G2=547 - 585.
I want to know please value of each band.

Regards Antonio

lucia.guardamino · December 19, 2022, 3:44pm

Hello Antonio,

I think there is a misunderstanding among three concepts: wavelengths, digital numbers (DN) and reflectance. From your question it seems you want to retrieve wavelengths. You can access this data reading the documentation of the dataset you are interested in (e.g., Landsat 7, Sentinel 2, SPOT, etc.). You won’t get this information by clicking on the pixels. Wavelengths vary depending on the bands that the selected sensor is sensitive to. For further information on this, you can refer to the following link: Newcomers Earth Observation Guide | ESA Business Applications

It’s not possible to retrieve wavelengths from the pixels, but you can get DN. In the case of Sentinel-2 L2A, DN are calculated based on the reflectance. DN = 10000 * REFLECTANCE

We have a dedicated ”Data” section, where you can get information of every dataset: https://docs.sentinel-hub.com/api/latest/data/

Finally, you can explore the Units in which the data is delivered by clicking on Units as shown in the image below: