2

I've had this error come up. Unfortunately the answers to similar questions on stack exchange are not applicable to my particular script.

I'm trying to account for sunglint so that I can improve my observations of seagrass beneath the ocean.

the full error reads as such - Sunglint Corrected: Layer error: Image.constant: Parameter 'value' is required.

Here is a link to my script: https://code.earthengine.google.com/f822b2089777eb1fa9318f187793a469

Here is my script

var dataset = ee.ImageCollection('COPERNICUS/S2_SR')
                  .filterDate('2021-02-12', '2021-07-25')
                  
                  .filter(ee.Filter.lt('CLOUDY_PIXEL_PERCENTAGE',20))
                  .filterBounds(roi)
                  
                  
                  .select(['B2','B3','B4','B1', 'B8']); 

                   
                  
                   
                   
                  
                  
var rgbVis = {
 min: 0.0,
 max: 1000,
 bands: ['B3', 'B2', 'B4'],
};

Map.addLayer(dataset, rgbVis, 'Filtered Collection'); 
var mosaic = dataset.mosaic();


var medianComposite = dataset.min(); 
Map.addLayer(medianComposite, rgbVis, 'Median Composite', 0);

var hansenImage = ee.Image('UMD/hansen/global_forest_change_2015');
var datamask = hansenImage.select('datamask');
var mask = datamask.eq(2);
var maskedComposite = medianComposite.updateMask(mask);
Map.addLayer(maskedComposite, rgbVis, 'masked');

Map.addLayer(maskedComposite, {
  bands: ['B4', 'B3', 'B2',],
  min: 0,
  max: 1000,
  scale:16,
}, 'BOA'); 

var B2 = maskedComposite.select(['B8', 'B2']);
var B3 = maskedComposite.select(['B8', 'B3']);
var B4 = maskedComposite.select(['B8', 'B4']);

var lfitB2 = B2.reduceRegion({
  reducer: ee.Reducer.linearFit(),
  geometry: glint,
  scale: 10,
  //tileScale: 16, 
  //maxPixels: 1000,
  //bestEffort: true
});

var lfitB3 = B3.reduceRegion({
  reducer: ee.Reducer.linearFit(),
  geometry: glint,
  scale: 10,
 // min: 0.0, 
  //maxPixels: 1000
  //tileScale: 16, 
  //maxPixels: 40e9,
  //bestEffort: true, 
});

var lfitB4 = B4.reduceRegion({
  reducer: ee.Reducer.linearFit(),
  geometry: glint,
  scale: 10,
 // min: 0.0, 
  //maxPixels: 1000
  //tileScale: 16, 
  //maxPixels: 40e9,
  //bestEffort: true, 
});

print(lfitB4)

//print('B2 OLS estimates:', lfitB2);
//print('B2 y-intercept:', lfitB2.get('offset'));
//print('B2 Slope:', lfitB2.get('scale'));
//print('B3 Slope:', lfitB3.get('scale'));
//print('B4 Slope:', lfitB4.get('scale'));

var slope_B2 = ee.Image.constant(lfitB2.get('scale')).clip(roi).rename('slope_B2');
var slope_B3 = ee.Image.constant(lfitB3.get('scale')).clip(roi).rename('slope_B3');
var slope_B4 = ee.Image.constant(lfitB4.get('scale')).clip(roi).rename('slope_B4');
var min_B8 = ee.Image.constant(maskedComposite.select('B8').reduceRegion(ee.Reducer.min(),roi, 3).get('B8')).rename('min_B8');

var glint_factors = ee.Image([slope_B2, slope_B3, slope_B4, min_B8]);
var S2 = maskedComposite.addBands(glint_factors);

/*var deglint_B2 = S2.select('B8').subtract(min_B8);
var deglint_B2 = slope_B2.multiply(deglint_B2);
var deglint_B2 = S2.select('B2').subtract(deglint_B2);
Map.addLayer(deglint_B2);*/

var deglint_B2 = S2.expression(
    'Blue - (Slope * (NIR - MinNIR))', {
    'Blue': S2.select('B2'),
    'NIR': S2.select('B8'),
    'MinNIR': S2.select('min_B8'),
    'Slope': S2.select('slope_B2')
}).rename('B2');

var deglint_B3 = S2.expression(
    'Green - (Slope * (NIR - MinNIR))', {
    'Green': S2.select('B3'),
    'NIR': S2.select('B8'),
    'MinNIR': S2.select('min_B8'),
    'Slope': S2.select('slope_B3')
}).rename('B3');

var deglint_B4 = S2.expression(
    'Red - (Slope * (NIR - MinNIR))', {
    'Red': S2.select('B4'),
    'NIR': S2.select('B8'),
    'MinNIR': S2.select('min_B8'),
    'Slope': S2.select('slope_B4')
}).rename('B4');

var S2_deglint = ee.Image([deglint_B2, deglint_B3, deglint_B4]);

Map.addLayer(S2_deglint, {
  bands: ['B4', 'B3', 'B2'],
  min: 0.0,
  max: 1000,
  scale: 16, 
  //tileScale: 16,
  bestEffort: true
}, 'Sunglint Corrected');

 var linkedMap = ui.Map();

//Map.addLayer(S2, {
//bands: ['B4', 'B3', 'B2'],
//min: 0.0,
//max: 40e9, 
//}, 'Top-of-Atmosphere Reflectance');

Map.addLayer(S2_deglint, {bands: ['B4', 'B3', 'B2'], min: 0.0, max: 1000, bestEffort: true, scale: 16}, 'Sunglint Corrected');

var linker = ui.Map.Linker([ui.root.widgets().get(0), linkedMap]);

var b2b3 = S2_deglint.select(['B2', 'B3']);
var b2b4 = S2_deglint.select(['B2', 'B4']);
var b3b4 = S2_deglint.select(['B3', 'B4']);

var lfitb2b3 = b2b3.reduceRegion({
  reducer: ee.Reducer.linearFit(),
  geometry: sand,
  scale: 16,
  bestEffort: true
});

var lfitb2b4 = b2b4.reduceRegion({
  reducer: ee.Reducer.linearFit(),
  geometry: sand,
  scale: 16,
});

var lfitb3b4 = b3b4.reduceRegion({
  reducer: ee.Reducer.linearFit(),
  geometry: sand,
  scale: 16,
});


var slope_b2b3 = ee.Image.constant(lfitb2b3.get('scale')).clip(roi).rename('slope_b2b3');
var slope_b2b4 = ee.Image.constant(lfitb2b4.get('scale')).clip(roi).rename('slope_b2b4');
var slope_b3b4 = ee.Image.constant(lfitb3b4.get('scale')).clip(roi).rename('slope_b3b4');

var dii_slopes = ee.Image([slope_b2b3, slope_b2b4, slope_b3b4]);
var S2_deglint = S2_deglint.addBands(dii_slopes);

var dii_b2b3 = S2_deglint.expression(
    'log(b2) - abs(slope * log(b3))', {
    'b2': S2_deglint.select('B2'),
    'b3': S2_deglint.select('B3'),
    'slope': S2_deglint.select('slope_b2b3')
}).rename('DII_b2b3');

var dii_b2b4 = S2_deglint.expression(
    'log(b2) - abs(slope * log(b4))', {
    'b2': S2_deglint.select('B2'),
    'b4': S2_deglint.select('B4'),
    'slope': S2_deglint.select('slope_b2b4')
}).rename('DII_b2b4');

var dii_b3b4 = S2_deglint.expression(
    'log(b3) - abs(slope * log(b4))', {
    'b3': S2_deglint.select('B3'),
    'b4': S2_deglint.select('B4'),
    'slope': S2_deglint.select('slope_b3b4')
}).rename('DII_b3b4');

var DII = ee.Image([dii_b2b3, dii_b2b4, dii_b3b4])

Map.addLayer(DII, {
  bands: ['DII_b2b4', 'DII_b3b4', 'DII_b2b3'],
  min: -7,
  max: -3
}, 'Depth-Invariant Index');

var training = maskedComposite.sample({
  region: roi,
  scale: 5,
  tileScale:   16, 
  numPixels: 3000
});

// Instantiate the clusterer and train it.
var clusterer = ee.Clusterer.wekaKMeans(5).train(training);

// Cluster the input using the trained clusterer.
var result = maskedComposite.cluster(clusterer);


// Display the clusters with random colors.
Map.addLayer(result.randomVisualizer(), {}, 'clusters');
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1 Answer 1

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1

Errors are produced because regression parameters are nulls (offset and scale) in some cases. It can be observed in following image for your original script:

enter image description here

So, I carefully tried out the script only for roi area, by implementing following modifications, and I got expected Sunglint Corrected image. You can modify the script for considering additional glint and sand geometries.

var dataset = ee.ImageCollection('COPERNICUS/S2_SR')
                  .filterDate('2021-02-12', '2021-07-25')
                  .filter(ee.Filter.lt('CLOUDY_PIXEL_PERCENTAGE',20))
                  .filterBounds(roi)
                  .select(['B2','B3','B4','B1', 'B8']); 

var rgbVis = {
 min: 0.0,
 max: 1000,
 bands: ['B3', 'B2', 'B4'],
};

Map.centerObject(roi, 16);
//Map.addLayer(dataset, rgbVis, 'Filtered Collection'); 
var mosaic = dataset.mosaic();

var medianComposite = dataset.min(); 
//Map.addLayer(medianComposite, rgbVis, 'Median Composite', 0);

var hansenImage = ee.Image('UMD/hansen/global_forest_change_2015');
var datamask = hansenImage.select('datamask');
var mask = datamask.eq(2);
var maskedComposite = medianComposite.updateMask(mask);
//Map.addLayer(maskedComposite, rgbVis, 'masked');
/*
Map.addLayer(maskedComposite, {
  bands: ['B4', 'B3', 'B2',],
  min: 0,
  max: 1000,
  scale:16,
}, 'BOA'); */

var B2 = maskedComposite.select(['B8', 'B2']);
var B3 = maskedComposite.select(['B8', 'B3']);
var B4 = maskedComposite.select(['B8', 'B4']);

var lfitB2 = B2.reduceRegion({
  reducer: ee.Reducer.linearFit(),
  geometry: roi,
  scale: 10,
  //tileScale: 16, 
  //maxPixels: 1000,
  //bestEffort: true
});

print(lfitB2);

var lfitB3 = B3.reduceRegion({
  reducer: ee.Reducer.linearFit(),
  geometry: roi,
  scale: 10,
 // min: 0.0, 
  //maxPixels: 1000
  //tileScale: 16, 
  //maxPixels: 40e9,
  //bestEffort: true, 
});

print(lfitB2);

var lfitB4 = B4.reduceRegion({
  reducer: ee.Reducer.linearFit(),
  geometry: roi,
  scale: 10,
 // min: 0.0, 
  //maxPixels: 1000
  //tileScale: 16, 
  //maxPixels: 40e9,
  //bestEffort: true, 
});

print(lfitB4);

var slope_B2 = ee.Image.constant(lfitB2.get('scale')).clip(roi).rename('slope_B2');
var slope_B3 = ee.Image.constant(lfitB3.get('scale')).clip(roi).rename('slope_B3');
var slope_B4 = ee.Image.constant(lfitB4.get('scale')).clip(roi).rename('slope_B4');
var min_B8 = ee.Image.constant(maskedComposite.select('B8').reduceRegion(ee.Reducer.min(),roi, 3).get('B8')).rename('min_B8');

var glint_factors = ee.Image([slope_B2, slope_B3, slope_B4, min_B8]);
var S2 = maskedComposite.addBands(glint_factors);

var deglint_B2 = S2.select('B8').subtract(min_B8);
var deglint_B2 = slope_B2.multiply(deglint_B2);
var deglint_B2 = S2.select('B2').subtract(deglint_B2);

var imageVisParam = {"opacity":1,
                     "bands":["B2"],
                     "min":-142.42184342256695,
                     "max":361,
                     "gamma":1};

//Map.addLayer(deglint_B2, imageVisParam, 'deglint_B2');

var deglint_B2 = S2.expression(
    'Blue - (Slope * (NIR - MinNIR))', {
    'Blue': S2.select('B2'),
    'NIR': S2.select('B8'),
    'MinNIR': S2.select('min_B8'),
    'Slope': S2.select('slope_B2')
}).rename('B2');

var deglint_B3 = S2.expression(
    'Green - (Slope * (NIR - MinNIR))', {
    'Green': S2.select('B3'),
    'NIR': S2.select('B8'),
    'MinNIR': S2.select('min_B8'),
    'Slope': S2.select('slope_B3')
}).rename('B3');

var deglint_B4 = S2.expression(
    'Red - (Slope * (NIR - MinNIR))', {
    'Red': S2.select('B4'),
    'NIR': S2.select('B8'),
    'MinNIR': S2.select('min_B8'),
    'Slope': S2.select('slope_B4')
}).rename('B4');

var S2_deglint = ee.Image([deglint_B2, deglint_B3, deglint_B4]);

Map.addLayer(S2_deglint, {
  bands: ['B4', 'B3', 'B2'],
  min: 0.0,
  max: 1000,
  scale: 16, 
  //tileScale: 16,
  bestEffort: true
}, 'Sunglint Corrected');

After running complete script in GEE code editor, it was obtained 'Sunglint Corrected' image; as it can be observed in following picture:

enter image description here

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2
  • Perfect! Thanks so much! Absolute life saver!
    – Alexander Murphy
    Jul 22, 2022 at 8:14
  • So, could you mark this answer as accepted? Thanks.
    – xunilk
    Jul 22, 2022 at 9:37

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