Questions tagged [normalized-difference-water-index]

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27 views

NDVI and NDWI making [closed]

Can we mask out a certain value from -1 to -1 from NDVI and NDWI so that we can acquire NDVI and NDWI value greater then required value range.
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Difference in output between NDVI by expression/formula or normalized difference in GEE

To calculate the NDVI, band maths or a normalized difference function can be used in GEE. However, the output generated with each method differs. Why is there a difference in output and how can this ...
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Landsat imagery corrections

I have downloaded Landsat collection 1 Level 1 imagery (Landsat 4,5,7 and 8) from https://earthexplorer.usgs.gov/. I would like to know that do we have to apply some conversions or corrections before ...
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25 views

Overcoming error : classified: Layer error: Image.reduceConnectedComponents: Label band must be integer valued, found type 'Float'

with following code , I am getting error message https://code.earthengine.google.com/15a22656f680c38ff0bf10afd2747c5f classified: Layer error: Image.reduceConnectedComponents: Label band must be ...
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10 views

Creating and Labeling time series (features)

I am trying to carry out crop type identification using optical remotely sensed data of Sentinel-2A. I am new to both fields (remote sensing and machine learning) and I want to use time series (NDVI, ...
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1answer
20 views

Georeferencing bands at first then calculating NDWI, or, calculating NDWI at first and then georeferencing it

I want to get NDWI from MODIS mod021km as GeoTIFF files. As far as you know, MODIS images are not georeferenced and the point is georeferencing these imagages is a little bit inaccurate (because of ...
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NDWI from Landsat-8 imagery

I am trying to calculate NDWI from Landsat-8 Band3(range:-113 to 11785) and Band5(range -89 to 12960) but the range of the resultant NDWI image is not valid (range: -215.181 to 1151.02). What is the ...
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54 views

How can I subtract one layer from another layer in Google Earth Engine?

I calculated NDSI and NDWI, NDWI disguises my water. I need to calculate the area of ​​snow, but I think that he considers all the snow and is masked. So I need to subtract (SNOW-WATER). And then ...
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1answer
75 views

how to remove small water bodies in binary mask array that we get from ndwi values?

I've detected water bodies in satellite images (modis, sentinel, landsat) in special area polygons, by ndwi values and based on special thresholds. area polygons and image tiles are coordinate ...
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34 views

Techniques to map small water bodies in desert

Techniques to map small water bodies in desert I have task to map water bodies in a desert. I used landsat 8 and calculated three indices called NDMI, Tasseled Cap Wetness, & AWEIsh. I am ...
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34 views

select waters pixels in GEE as magic wand tool

I am interested to map small water bodies in a desert . I used Gond method described in an article entitled "An Assessment of Surface Water Detection Methods for Water Resource Management in the ...
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29 views

Cloud Shadow interferring with NDWI Analysis

I'm working on surface water identification in Northern Kenya. I'm using Landsat 5TM and Landsat 8OLI data in ENVI 5. I've masked clouds using the QA band (although have also tried the fmask tool- ...
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How to average the NDDI index for a map in GEE

In previous codes I was able to generate the NDVI average, but since NDDI is a sub-index I would like to know if anyone would be able to generate this NDDI average in GEE https://code.earthengine....
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124 views

PlanetScope NDWI calculations

I am trying to calculate NDWI for a PlanetScope image scene. I currently have 2 products: one is the "3B_AnalyticMS_SR.tif" and the other is the "3B_AnalyticMS.tif" product. I believe the former is ...
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51 views

Printing NDWI and NDVI comparision graph

Trying to print the chart for both NDVI and NDWI function addNDVI(image) { var ndvi = image.normalizedDifference(['B4', 'B3']); return image.addBands(ndvi); } ...
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1answer
76 views

How to print chart for NDWI

Trying to compute chart for NDWI var dataset = ee.ImageCollection('LANDSAT/LE07/C01/T1_8DAY_NDWI') .filterDate('1999-01-01', '2002-12-31') .filterBounds(...
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1answer
283 views

Water pixel detection in Landsat imagery using Google Earth Engine

I want to extract or detect water bodies in a selected region using the relationship between water and vegetation indices, and these water and vegetation indices were calculated by using the cloud and ...
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1answer
259 views

NDWI generation from google earth engine

I want to generate the median composite image of ndwi images of several dates in google earth engine. How can I do that and how to shorten the code itelf? var image5 = L5.filterDate('1987-01-01','...
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38 views

How to export NDWI images one by one?

I am using GEE and I'm pretty new with this engine. I'm trying to download several images from Landsat collection. I provide the script for you. Here is my question: How can I download each NDWI ...
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71 views

Comparing NDWI regions with a given shapefile Google Earth Engine Python?

With the code below, I computed the NDVI, NDWI and NDWIMOD indices of a R.O.I. in order to detect water areas in that R.O.I. Now, my goal concerns to compare the water areas with a given shapefile ...
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58 views

Unable to use ee.Kernel Google Earth Engine pyhon API

I'm trying to use the ee.Kernel Google Earth Engine pyhon API in the following code: import ee import ee.mapclient ee.Initialize() ee.mapclient.centerMap(15.88, 41.78, 10) def maskS2clouds(...
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31 views

Output of layer consisting pixel value 1 and 0 totally black?

I am computing the NDWI of an area , and I used the code below to generate a result of pixel value 1 and 0 only. Pixel value 1 will be displayed in blue means the pixel's NDWI value once had exceeded ...
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330 views

Export stacked layers of images as a thumbnail URL in GEE

I am computing different normalized index like NDVI, NDWI, NDBI, UI and adding them as layers stacked on top of Sentinel 2-1C Image patch. I would like to download the generated stacked image as a ...
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Calculate NDWI of each image in a Imagecollection?

var L8 = ee.ImageCollection("LANDSAT/LC08/C01/T1_TOA") .filterDate('2016-06-01', '2016-07-31') // you can change date here .filter(ee.Filter.lt("CLOUD_COVER", 0.75)) .filterBounds(collection[i]) .map(...
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1answer
124 views

Google Earth Engine -Iterated image of NDWI

I computed the NDWI of the whole image collection and I expect to output an image that shows water body whenever it has been flooded , even once , throughout the filtered date. Somehow the output ...
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200 views

Why mNDWI can detect the shallow water area but ignores the deep water area?

I'm using Landsat 8 in Google Earth Engine to detect the water body in Jiangsu and Zhejiang area, China. The formula is: mNDWI = (Green-SWIR)/(Green+SWIR) I applied this formula to GEE code, and it ...
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1answer
311 views

Calculate water frequency in Google Earth Engine based on time series?

I have the Landsat 8 images cover southern Florida during 2017 (from Jan 1st to Dec 31st), with the cloud, scan edges and other bad observation pixels eliminated. I have also calculated several ...
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1answer
113 views

How to compute the conditional function and output binary image in GEE?

I am now using Google Earth Engine to process the Landsat 8 images. Now I have calculated NDVI, EVI, mNDWI and generated some maps. I am now want to generate a function based on those indices values, ...
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Performing unsupervised classification using ArcGIS Desktop?

How to distinguish between water bodies and clouds using unsupervised classification in sentinel 2? When i used NDWI and NDSI both are same objects.
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104 views

Clip a Mask (NDSI) from another Mask (NDWI) in GEE

I have created a mask of Normalized difference Snow Index (NDSI) in the late winter using a combination of Landsat 5,7,8 imagery and I would like to only keep a remaining land features by clipping out ...
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673 views

Treatment of Landsat 7 SLC error in Google Earth Engine?

Google Earth Engine distributes Landsat 7 image composites of indeces such as NDWI and NDVI that, when averaged on a shapefile, give back a coherent value. But how is SLC failure treated by it https:/...
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580 views

How is Landsat NDWI calculated in Google Earth Engine?

I am using Google Earth Engine to compute NDWI time series, in particular by plotting "Landsat 7 Collection 1 Tier 1 8-Day NDWI Composite" data values The product description says: These Landsat 7 ...
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1answer
1k views

Reclassifying NDWI using Google Earth Engine?

I'm trying to reclassify a NDWI raster into 1 for values >0.4 and 0 for <0.4. I understand that its possible to use .remap in case of discrete values, but not sure how to reclassify NDWI raster ...
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1k views

Binarization of water body extraction in Google Earth Engine?

I'm a new learner of Google Earth Engine. What I am doing right now is to extract water bodies from Landsat 8 using such water index as NDWI(normalized difference water index) in GEE. Is there any ...
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322 views

Getting extreme values for NDWI calculation for Landsat 8 Imagery

I am currently in a remote sensing course at my university and am working on a change detection project. I am having some trouble creating an ndwi raster from landsat 8 imagery. I am using arcgis 10.5....
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711 views

NDWI Calculation with Surface Reflectance Products

I have downloaded L8 OLI/TIRS C1 Higher Level Data from USGS Earth Explorer to map Chlorophyll content in lake. The file contains original images and surface reflectance images. When I calculate NDWI ...
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1k views

How to remove negative values from RasterLayer in R

I am processing Landsat 8 images to detect water quality parameters in R. I am using NDWI to masking the images. The raster layer I obtained from NDWI has negative values which I wanted to remove. Can ...
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2answers
239 views

Applying Maximum Likelihood Classification to a single band (NDWI)

I have applied ML to a single band file, specifically a NDWI (McFeeters version). Comparing the results of this classification, with ML applied too a normal 5 band RapidEye Scene, the first one gave ...
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1answer
925 views

Masking Water Bodies to build surface temperature raster slice of them in ENVI?

I am looking at a region in the Alaskan tundra, there are plenty of small water bodies in my scene. I need to mask these bodies, so that I can perform a surface temperature/emissivity normalization ...
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1answer
169 views

Water discrimination by Remote sensing

I have NIR, green, red edge, red, IR bands at disposal of a an area with a river, I want to discriminate water surfaces, do you have any good ideas on how to do that ? I did a NDWI which is not very ...
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1answer
1k views

Converting Landsat 8 to TOA for NDWI calculation

I am trying to use Landsat to identify small-scale water bodies in Eastern Africa. I first pansharpened a composite image of bands 2-7 to improve the resolution. Bands 2-4 are now at a resolution of ...
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3k views

How to Calculate NDWI Value in Arcgis 10.1?

I want to delineate surface water feature of my Landsat raster image and also want to calculate the area of water body. I have learned through internet that NDWI can be used to delineate open water ...