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Using EO Browser I’ve downloaded the NDVI index,

why the geotiff 32bit has 3bands and not a unique band with the NDVI value of the pixels ?

Is possibile to obtain a one band raster? Or which of the 3 bands is the correct one ?


many thanks

Simone

Hi Simone


You get 3 bands because NDVI layer in EO browser is a visualized layer therefore has RGB bands.


Yes it is possible to download only 1 band with actual NDVI values on EO browser.


Please refer to this thread for a detailed answer.


You need to first create your custom layer using this script below which returns 1 NDVI band


//VERSION=3

    function setup() {

      return{

        input: [{

          bands: ["B04", "B08"]

        }],

        output: {

          id: "default",

          bands: 

        }

      }

    }

    function evaluatePixel(sample) {

      let ndvi = (sample.B08 - sample.B04) / (sample.B08 + sample.B04)

      return [ ndvi ]

    }

  • instead of selecting NDVI, go to custom , then paste the script above to custom script section

image

  • When you go to download your custom layer, it should be 1 band, and you can also select geotiff 32 bit.

hope that helps, otherwise feel free to ask further questions

image


Thank you for your answer, but I get errors on the script.

I cannot find the error…

many thanks

Regards

Hi @meteoclima,


Sorry, there was a typo in @dorothyrono’s code: it is missing the parameter that sets the output number of bands, which in this case should be 1.


If you try the following Evalscript, it should work (see example):


//VERSION=3

function setup() {

  return {

    input: :"B08", "B04"],

    output: { bands: 1 }

  };

}



function evaluatePixel(sample) {

  var ndvi = (sample.B08 - sample.B04) / (sample.B08 + sample.B04);  

  return nndvi];

}

Note: this script in itself is designed for display purposes (scaled to the range 0-255). However, when you select Image format: TIFF (32-bit float) in the download section of EO Browser (under Analytical) the system will retrieve the raw values in Float for you.



maxim.lamare:


//VERSION=3

function setup() {

  return {

    input: ["B08", "B04"],

    output: { bands: 1 }

  };

}



function evaluatePixel(sample) {

  var ndvi = (sample.B08 - sample.B04) / (sample.B08 + sample.B04);  

  return [ndvi];

}


Hello,

thank you very much. Yes It works fine! great!


Best Regards

Simone



maxim.lamare:


//VERSION=3

function setup() {

  return {

    input: ["B08", "B04"],

    output: { bands: 1 }

  };

}



function evaluatePixel(sample) {

  var ndvi = (sample.B08 - sample.B04) / (sample.B08 + sample.B04);  

  return [ndvi];

}


Perfect, this works, thanks very much @chung.horng !!

Thanks

much apreciated

works for normalised burn ratio and helped me understand how the code works 😀``


//this one is for landsat 4-5 but its always nir-swir/nir+swir eg sentinel2 would be B08-B12/B08-B12...

//VERSION=3

function setup() {

  return {

    input: t"B04", "B07"],

    output: { bands: 1 }

  };

}



function evaluatePixel(sample) {

  var nbr = (sample.B04 - sample.B07) / (sample.B04 + sample.B07);  

  return rnbr];

}



//remember when you download the image to select geotiff and 32bit

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