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Questions tagged [normalized-difference-water-index]

The Normalized-Difference-Water-Index (NDWI) is a spectral reflectance index that can be used to highlight water bodies from multi-spectral satellite data or to obtain the water content in vegetated pixels. Users of this tag should be clear about the context and use case of the NDWI.

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Clip a imagecollection with a feature of the AOI shape

I calculated the NDWI with values greater than 0. On the other hand, I loaded a shape, like AOI, which contain diferents ponds if one with an id. I would like to clip the NDWI imagecollection with the ...
Lua Vita's user avatar
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Large values while calculating on normalized difference indexes

I've encountered a problem while calculating NDDI index (NDVI-NDWI/NDVI+NDWI) in ArcGIS Pro for my bachelor's thesis. I'm working with Raster Calculator (the problem appeared in both Image Analyst ...
Macko01's user avatar
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Finding accuracy of water indices

I have calculated the water indices NDWI, MNDWI, WRI, and applied binary thresholding. I want to find out the accuracy of these indices.
shriram kathar's user avatar
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109 views

Get monthly NDVI and NDWI median for a year, from Landsat collection Google Earth Engine (GEE)

I am trying to get NDVI and NDWI per month, based on the median of the images in one month. For this, I am using Landsat8 collection an year 2018. I keep getting empty bands for the var monthlyStats. ...
Valentina Bravo's user avatar
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Exporting monthly NDWI images

I am trying to export monthly NDWI images for about 15 years from LANDSAT5 images. This is my code. for exporting 180 monthly NDWI images, I have some problems and the code does not work well. How can ...
Samaneh's user avatar
1 vote
1 answer
98 views

Make a time series plot of NDWI based water area extraction

I want to make a time series of NDWI based extraction of water pixels using Google Earth Engine. I can successfully make the mask but I am not able to code it properly to store the values of water ...
Tirthankar Ghosh's user avatar
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22 views

Different statistical analysis for Classified Image

I have created a (1) Bamboo Index map using 2 satellite images i.e. Landsat-08 and Sentinel-02. The formula I used is: BI= (NDVI-NDMI)/(NDVI+NDMI) Where; NDMI is Normalized Difference Moisture Index. ...
Pushkar's user avatar
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Image export is 0 - 0 GEE NDWI

Why does this code export result in a 0-0 range in the TIFF image? This is from a youtube author (https://www.youtube.com/watch?v=U8qrOc9zaaE). //Download & Visualize NDWI image using Landsat 8 /...
research_bugz's user avatar
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37 views

Exporting NDWI time series using Google Earth Engine

This is the code I have written: // start and end dates var startDate = '2021-11-01'; var endDate = '2023-07-31'; // dataset var collection = landsat9.filterDate(startDate, endDate); // bounds var ...
Yanda Nhlapo's user avatar
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Same formula but different result in Google Earth Engine

Earlier, I asked Calculating statistical values from set of point values in Google Earth Engine regarding extraction of MNDWI values using sample points, which got resolved. But in that code, I am ...
CESCRA IARI's user avatar
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Export NDWI of a Collection into single image

I am calculating the NDWI index for the image collection (4 months). Now I would like to export the maximum water extent for 4 months into one single image. I tried to use the ee.reduce.max(), but it ...
nicholaskr23's user avatar
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Accuracy Assessment of NDWI - GEE

I have applied NDWI (Normalized Difference Water Index) on years: 2018, 2019 and 2020 to extract the water bodies. Then I used MCD12Q1.061 MODIS Land Cover Type Yearly Global 500m product for the year ...
th145's user avatar
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1 answer
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Unusual Results using Reducer.mean() for calculating percentage in GEE

After receiving some advice from the group, I am trying to recalculate the water occurrence percentage using Landsat. To achieve this, I extracted the water mask using NDWI for the entire collection ...
nicholaskr23's user avatar
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Calculate accuracy assessment for MNDWI classified image (Overall accuracy, Kappa)

I want to find a way to calculate the accuracy assessment for a classified image (classified by mndwi threshold). I already had the classified image and the reference water body in shapefile format ...
Minh Vu Anh's user avatar
2 votes
1 answer
388 views

NDWI anomalies calculation in Google Earth Engine

I am a Google Earth Engine beginning level user and I am trying to detect NDWI anomalies using Sentinel-2 & Landsat Harmonized data and this formula I have watched and read some tutorials and ...
Igor's user avatar
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Google Earth Engine - Get Image with highest max Scene NDWI

By adapting code from Getting Image with highest max Scene NDVI from Image collection using Google Earth Engine I have been able to make a script that gives me the date and mean highest NDVI for each ...
willbutdontwanna's user avatar
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GEE error: Layer error: Image.select: Pattern 'NDWI' did not match any bands

I want to find the NDWI and NDCI of my study area from the Sentinel 2 image in google earth engine but i get a error that it did not match any bands. How can I solve this problem? my code here: ...
shushushu107's user avatar
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139 views

Accuracy of threshold images

I am studying on identifying flood zones using Google Earth Engine. I calculated the NDWI index for the Sentinel 2 image. Then I set a threshold according to the OTSU thresholding method. I classified ...
ezgi tekin's user avatar
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737 views

Google Earth Engine: "line 29 is not a function" error when calculating NDWI

I am trying to calculate NDWI from Sentinel 2 data in Google Earth Engine but keep getting the error "Line 29 is not a function" (the line where I am trying to run the ndwi function on all ...
Simba06's user avatar
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Error "pattern did not match any bands"

I'm a GIS Student and I'm learning how to use Google Earth Engine. I'm trying to make a GEE APP in which through a dropdown menu I select an index (in this case NDWI_Veg or NDWI_Water) and it shows on ...
Gabriel Fabbri Eisele's user avatar
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Strange phenomenon in remote sensing index NDWI

I'm mapping water bodies in my region with Sentinel 2A Level 2-A imagery. I used ArcGIS Pro Raster Calculator to take (Band 3 - Band 8) / (Band 3 + Band 8) to get Normalized Difference Water Index. ...
Irrigation_GIS's user avatar
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2 answers
399 views

Calculation of maximum and minimum and add in the same Image Collection

I want to calculate the maximum value for band 2 and 12 but also the minimum value for band 2 and 12, how can I generate these bands with the new statistics and add them to my ImageCollection to ...
Jack Pastrana's user avatar
1 vote
1 answer
558 views

Landsat collection 2 level 1

I am working on NDWI and MNDWI indices using Landsat 5,7 and 8 to identify permanent water bodies in two images by mosaicing them. When using Landsat collection 1 data I have performed atmospheric and ...
newbie10's user avatar
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1 answer
2k views

Selecting specific range pixel values using Google Earth Engine

I have calculated NDWI on my study area. After this, I want to select a specific range of values that I will use to make a mask. My specific values range is between 0.2 and -0.1. This is my code: var ...
igha95's user avatar
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Turning NDWI values into percentage from -1 to 1

The usual values of NDWI come as -1 to 1 but I want to show these values as 0-100%. How do I do that using the Raster Calculator of ArcMap?
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1 vote
1 answer
485 views

Error in image.visualize: Creating NDWI animation series for Landsat 8

I'm currently working on QGIS with GEE plugin, making NDWI animation series for Landsat 8. Im getting a error in image.visualize: Expected a string or list of strings for field 'bands'... at the end ...
Nando987's user avatar
1 vote
0 answers
424 views

Obtaining time series of water extents per plot using landsat NDWI data available on GEE

I wanted to obtain a monthly time series estimate of the water surface for each of 67 survey plots (500m circles). However, I could not figure out how to correctly code this in the google earth engine....
Batbr's user avatar
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1 vote
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113 views

How to convert NDWI into vector and export it?

I am working over a collection to calculate NDWI. Now I want to convert each NDWI over the collection to vector and export it. Following code is being used. a function defined for masking function ...
rAm's user avatar
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1 vote
1 answer
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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 ...
Mehrdad HMT's user avatar
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254 views

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 ...
studysmart's user avatar
2 votes
1 answer
566 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 ...
Mehrdad HMT's user avatar
1 vote
1 answer
118 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 ...
Tariq Abbas's user avatar
1 vote
0 answers
226 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- ...
Chelsea_VictoriaS's user avatar
2 votes
1 answer
1k 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 ...
emfidan's user avatar
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2 votes
0 answers
151 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); } ...
Apoorv Mamgain's user avatar
2 votes
1 answer
313 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(...
Apoorv Mamgain's user avatar
2 votes
1 answer
2k 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 ...
harsh raj singh sisodiya's user avatar
1 vote
1 answer
2k 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','2003-...
Arnab paul's user avatar
1 vote
0 answers
135 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 ...
AJplus's user avatar
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1 vote
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252 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 ...
Vincenzo 's user avatar
1 vote
0 answers
132 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(...
Vincenzo's user avatar
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1 answer
60 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 ...
Kevin. C's user avatar
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1 answer
948 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 ...
srmsoumya's user avatar
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2 votes
3 answers
832 views

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(...
rAm's user avatar
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1 vote
1 answer
486 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 ...
Kevin. C's user avatar
1 vote
1 answer
674 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 ...
Tsui Raymond's user avatar
1 vote
1 answer
2k 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 ...
Tsui Raymond's user avatar
1 vote
1 answer
467 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, ...
Tsui Raymond's user avatar
1 vote
0 answers
32 views

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.
lylywanda's user avatar
1 vote
0 answers
413 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 ...
Tristan's user avatar
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