Function to calculate red-edgeNDVI in Google Earth Engine





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I am trying to calculate the red-edgeNDVI ((NIR – red edge)/(NIR + red edge)) of an Image.Collection in Google Earth Engine. There is a built in function for NDVI but not for red-edge NDVI. The code I have is below but I get the error message "image.NIR is undefined". I'm sure this is a simple syntax issue related to the function but I've tried everything I could think of and I just can't get it to work. Any GEE/java experts who can tell me what I'm missing?



/**
* Function to mask clouds using the Sentinel-2 QA band
* @param {ee.Image} image Sentinel-2 image
* @return {ee.Image} cloud masked Sentinel-2 image
*/
function maskS2clouds(image) {
var qa = image.select('QA60');

// Bits 10 and 11 are clouds and cirrus, respectively.
var cloudBitMask = 1 << 10;
var cirrusBitMask = 1 << 11;

// Both flags should be set to zero, indicating clear conditions.
var mask = qa.bitwiseAnd(cloudBitMask).eq(0)
.and(qa.bitwiseAnd(cirrusBitMask).eq(0));

return image.updateMask(mask)
.divide(10000);
}

// Load Sentinel-2 TOA reflectance data.
var S2 = ee.ImageCollection('COPERNICUS/S2')
.filterDate('2017-06-01', '2017-09-30')
// Pre-filter to get less cloudy granules.
.filter(ee.Filter.lt('CLOUDY_PIXEL_PERCENTAGE', 20))
//Select required bands only
.select('B2', 'B3', 'B4', 'B5', 'B6', 'B7', 'B8', 'B8A', 'QA60')
//Apply cloud mask
.map(maskS2clouds);

//Create band variables
var redEdge = S2.select('B5');
var NIR = S2.select('B8');

//Function to calculate redEdgeNDVI
var add_reNDVI = function(image){
var redEdgeNDVI = image.NIR.subtract(redEdge).divide(NIR.add(redEdge)).rename('reNDVI');
return image.addBands(reNDVI);
};









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    1















    I am trying to calculate the red-edgeNDVI ((NIR – red edge)/(NIR + red edge)) of an Image.Collection in Google Earth Engine. There is a built in function for NDVI but not for red-edge NDVI. The code I have is below but I get the error message "image.NIR is undefined". I'm sure this is a simple syntax issue related to the function but I've tried everything I could think of and I just can't get it to work. Any GEE/java experts who can tell me what I'm missing?



    /**
    * Function to mask clouds using the Sentinel-2 QA band
    * @param {ee.Image} image Sentinel-2 image
    * @return {ee.Image} cloud masked Sentinel-2 image
    */
    function maskS2clouds(image) {
    var qa = image.select('QA60');

    // Bits 10 and 11 are clouds and cirrus, respectively.
    var cloudBitMask = 1 << 10;
    var cirrusBitMask = 1 << 11;

    // Both flags should be set to zero, indicating clear conditions.
    var mask = qa.bitwiseAnd(cloudBitMask).eq(0)
    .and(qa.bitwiseAnd(cirrusBitMask).eq(0));

    return image.updateMask(mask)
    .divide(10000);
    }

    // Load Sentinel-2 TOA reflectance data.
    var S2 = ee.ImageCollection('COPERNICUS/S2')
    .filterDate('2017-06-01', '2017-09-30')
    // Pre-filter to get less cloudy granules.
    .filter(ee.Filter.lt('CLOUDY_PIXEL_PERCENTAGE', 20))
    //Select required bands only
    .select('B2', 'B3', 'B4', 'B5', 'B6', 'B7', 'B8', 'B8A', 'QA60')
    //Apply cloud mask
    .map(maskS2clouds);

    //Create band variables
    var redEdge = S2.select('B5');
    var NIR = S2.select('B8');

    //Function to calculate redEdgeNDVI
    var add_reNDVI = function(image){
    var redEdgeNDVI = image.NIR.subtract(redEdge).divide(NIR.add(redEdge)).rename('reNDVI');
    return image.addBands(reNDVI);
    };









    share|improve this question

























      1












      1








      1








      I am trying to calculate the red-edgeNDVI ((NIR – red edge)/(NIR + red edge)) of an Image.Collection in Google Earth Engine. There is a built in function for NDVI but not for red-edge NDVI. The code I have is below but I get the error message "image.NIR is undefined". I'm sure this is a simple syntax issue related to the function but I've tried everything I could think of and I just can't get it to work. Any GEE/java experts who can tell me what I'm missing?



      /**
      * Function to mask clouds using the Sentinel-2 QA band
      * @param {ee.Image} image Sentinel-2 image
      * @return {ee.Image} cloud masked Sentinel-2 image
      */
      function maskS2clouds(image) {
      var qa = image.select('QA60');

      // Bits 10 and 11 are clouds and cirrus, respectively.
      var cloudBitMask = 1 << 10;
      var cirrusBitMask = 1 << 11;

      // Both flags should be set to zero, indicating clear conditions.
      var mask = qa.bitwiseAnd(cloudBitMask).eq(0)
      .and(qa.bitwiseAnd(cirrusBitMask).eq(0));

      return image.updateMask(mask)
      .divide(10000);
      }

      // Load Sentinel-2 TOA reflectance data.
      var S2 = ee.ImageCollection('COPERNICUS/S2')
      .filterDate('2017-06-01', '2017-09-30')
      // Pre-filter to get less cloudy granules.
      .filter(ee.Filter.lt('CLOUDY_PIXEL_PERCENTAGE', 20))
      //Select required bands only
      .select('B2', 'B3', 'B4', 'B5', 'B6', 'B7', 'B8', 'B8A', 'QA60')
      //Apply cloud mask
      .map(maskS2clouds);

      //Create band variables
      var redEdge = S2.select('B5');
      var NIR = S2.select('B8');

      //Function to calculate redEdgeNDVI
      var add_reNDVI = function(image){
      var redEdgeNDVI = image.NIR.subtract(redEdge).divide(NIR.add(redEdge)).rename('reNDVI');
      return image.addBands(reNDVI);
      };









      share|improve this question














      I am trying to calculate the red-edgeNDVI ((NIR – red edge)/(NIR + red edge)) of an Image.Collection in Google Earth Engine. There is a built in function for NDVI but not for red-edge NDVI. The code I have is below but I get the error message "image.NIR is undefined". I'm sure this is a simple syntax issue related to the function but I've tried everything I could think of and I just can't get it to work. Any GEE/java experts who can tell me what I'm missing?



      /**
      * Function to mask clouds using the Sentinel-2 QA band
      * @param {ee.Image} image Sentinel-2 image
      * @return {ee.Image} cloud masked Sentinel-2 image
      */
      function maskS2clouds(image) {
      var qa = image.select('QA60');

      // Bits 10 and 11 are clouds and cirrus, respectively.
      var cloudBitMask = 1 << 10;
      var cirrusBitMask = 1 << 11;

      // Both flags should be set to zero, indicating clear conditions.
      var mask = qa.bitwiseAnd(cloudBitMask).eq(0)
      .and(qa.bitwiseAnd(cirrusBitMask).eq(0));

      return image.updateMask(mask)
      .divide(10000);
      }

      // Load Sentinel-2 TOA reflectance data.
      var S2 = ee.ImageCollection('COPERNICUS/S2')
      .filterDate('2017-06-01', '2017-09-30')
      // Pre-filter to get less cloudy granules.
      .filter(ee.Filter.lt('CLOUDY_PIXEL_PERCENTAGE', 20))
      //Select required bands only
      .select('B2', 'B3', 'B4', 'B5', 'B6', 'B7', 'B8', 'B8A', 'QA60')
      //Apply cloud mask
      .map(maskS2clouds);

      //Create band variables
      var redEdge = S2.select('B5');
      var NIR = S2.select('B8');

      //Function to calculate redEdgeNDVI
      var add_reNDVI = function(image){
      var redEdgeNDVI = image.NIR.subtract(redEdge).divide(NIR.add(redEdge)).rename('reNDVI');
      return image.addBands(reNDVI);
      };






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      asked 9 hours ago









      Adam GAdam G

      262




      262






















          1 Answer
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          3














          In your code, S2 is an ImageCollection, so when you "create band variables" you're just getting ImageCollections in which every image inside has only the selected band, which is useful. As you well commented, add_reNDVI is a function that will take every image in the collection and calculate reNDVI. So you have to map that function over the collection to get what you want.



          // Load Sentinel-2 TOA reflectance data.
          var S2 = ee.ImageCollection('COPERNICUS/S2')
          .filterDate('2017-06-01', '2017-09-30')
          // Pre-filter to get less cloudy granules.
          .filter(ee.Filter.lt('CLOUDY_PIXEL_PERCENTAGE', 20))
          //Select required bands only
          .select('B2', 'B3', 'B4', 'B5', 'B6', 'B7', 'B8', 'B8A', 'QA60')
          //Apply cloud mask
          .map(maskS2clouds);

          //Function to calculate redEdgeNDVI
          var add_reNDVI = function(image){
          //Create band variables
          var redEdge = image.select('B5');
          var NIR = image.select('B8');
          var redEdgeNDVI = NIR.subtract(redEdge).divide(NIR.add(redEdge)).rename('reNDVI');
          return image.addBands(redEdgeNDVI);
          };
          var s2_reNDVI = S2.map(add_reNDVI)
          Map.centerObject(s2_reNDVI.first())
          Map.addLayer(s2_reNDVI.first())


          I guess you'll need to filter by bounds at some point, that is why I just took the first image out of the collection to check if it's working






          share|improve this answer
























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            1 Answer
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            active

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            1 Answer
            1






            active

            oldest

            votes









            active

            oldest

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            active

            oldest

            votes









            3














            In your code, S2 is an ImageCollection, so when you "create band variables" you're just getting ImageCollections in which every image inside has only the selected band, which is useful. As you well commented, add_reNDVI is a function that will take every image in the collection and calculate reNDVI. So you have to map that function over the collection to get what you want.



            // Load Sentinel-2 TOA reflectance data.
            var S2 = ee.ImageCollection('COPERNICUS/S2')
            .filterDate('2017-06-01', '2017-09-30')
            // Pre-filter to get less cloudy granules.
            .filter(ee.Filter.lt('CLOUDY_PIXEL_PERCENTAGE', 20))
            //Select required bands only
            .select('B2', 'B3', 'B4', 'B5', 'B6', 'B7', 'B8', 'B8A', 'QA60')
            //Apply cloud mask
            .map(maskS2clouds);

            //Function to calculate redEdgeNDVI
            var add_reNDVI = function(image){
            //Create band variables
            var redEdge = image.select('B5');
            var NIR = image.select('B8');
            var redEdgeNDVI = NIR.subtract(redEdge).divide(NIR.add(redEdge)).rename('reNDVI');
            return image.addBands(redEdgeNDVI);
            };
            var s2_reNDVI = S2.map(add_reNDVI)
            Map.centerObject(s2_reNDVI.first())
            Map.addLayer(s2_reNDVI.first())


            I guess you'll need to filter by bounds at some point, that is why I just took the first image out of the collection to check if it's working






            share|improve this answer




























              3














              In your code, S2 is an ImageCollection, so when you "create band variables" you're just getting ImageCollections in which every image inside has only the selected band, which is useful. As you well commented, add_reNDVI is a function that will take every image in the collection and calculate reNDVI. So you have to map that function over the collection to get what you want.



              // Load Sentinel-2 TOA reflectance data.
              var S2 = ee.ImageCollection('COPERNICUS/S2')
              .filterDate('2017-06-01', '2017-09-30')
              // Pre-filter to get less cloudy granules.
              .filter(ee.Filter.lt('CLOUDY_PIXEL_PERCENTAGE', 20))
              //Select required bands only
              .select('B2', 'B3', 'B4', 'B5', 'B6', 'B7', 'B8', 'B8A', 'QA60')
              //Apply cloud mask
              .map(maskS2clouds);

              //Function to calculate redEdgeNDVI
              var add_reNDVI = function(image){
              //Create band variables
              var redEdge = image.select('B5');
              var NIR = image.select('B8');
              var redEdgeNDVI = NIR.subtract(redEdge).divide(NIR.add(redEdge)).rename('reNDVI');
              return image.addBands(redEdgeNDVI);
              };
              var s2_reNDVI = S2.map(add_reNDVI)
              Map.centerObject(s2_reNDVI.first())
              Map.addLayer(s2_reNDVI.first())


              I guess you'll need to filter by bounds at some point, that is why I just took the first image out of the collection to check if it's working






              share|improve this answer


























                3












                3








                3







                In your code, S2 is an ImageCollection, so when you "create band variables" you're just getting ImageCollections in which every image inside has only the selected band, which is useful. As you well commented, add_reNDVI is a function that will take every image in the collection and calculate reNDVI. So you have to map that function over the collection to get what you want.



                // Load Sentinel-2 TOA reflectance data.
                var S2 = ee.ImageCollection('COPERNICUS/S2')
                .filterDate('2017-06-01', '2017-09-30')
                // Pre-filter to get less cloudy granules.
                .filter(ee.Filter.lt('CLOUDY_PIXEL_PERCENTAGE', 20))
                //Select required bands only
                .select('B2', 'B3', 'B4', 'B5', 'B6', 'B7', 'B8', 'B8A', 'QA60')
                //Apply cloud mask
                .map(maskS2clouds);

                //Function to calculate redEdgeNDVI
                var add_reNDVI = function(image){
                //Create band variables
                var redEdge = image.select('B5');
                var NIR = image.select('B8');
                var redEdgeNDVI = NIR.subtract(redEdge).divide(NIR.add(redEdge)).rename('reNDVI');
                return image.addBands(redEdgeNDVI);
                };
                var s2_reNDVI = S2.map(add_reNDVI)
                Map.centerObject(s2_reNDVI.first())
                Map.addLayer(s2_reNDVI.first())


                I guess you'll need to filter by bounds at some point, that is why I just took the first image out of the collection to check if it's working






                share|improve this answer













                In your code, S2 is an ImageCollection, so when you "create band variables" you're just getting ImageCollections in which every image inside has only the selected band, which is useful. As you well commented, add_reNDVI is a function that will take every image in the collection and calculate reNDVI. So you have to map that function over the collection to get what you want.



                // Load Sentinel-2 TOA reflectance data.
                var S2 = ee.ImageCollection('COPERNICUS/S2')
                .filterDate('2017-06-01', '2017-09-30')
                // Pre-filter to get less cloudy granules.
                .filter(ee.Filter.lt('CLOUDY_PIXEL_PERCENTAGE', 20))
                //Select required bands only
                .select('B2', 'B3', 'B4', 'B5', 'B6', 'B7', 'B8', 'B8A', 'QA60')
                //Apply cloud mask
                .map(maskS2clouds);

                //Function to calculate redEdgeNDVI
                var add_reNDVI = function(image){
                //Create band variables
                var redEdge = image.select('B5');
                var NIR = image.select('B8');
                var redEdgeNDVI = NIR.subtract(redEdge).divide(NIR.add(redEdge)).rename('reNDVI');
                return image.addBands(redEdgeNDVI);
                };
                var s2_reNDVI = S2.map(add_reNDVI)
                Map.centerObject(s2_reNDVI.first())
                Map.addLayer(s2_reNDVI.first())


                I guess you'll need to filter by bounds at some point, that is why I just took the first image out of the collection to check if it's working







                share|improve this answer












                share|improve this answer



                share|improve this answer










                answered 8 hours ago









                Rodrigo E. PrincipeRodrigo E. Principe

                4,54111021




                4,54111021






























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