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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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 ...
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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 ...
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Area of a lake over time using Google Earth Engine
Currently, I am working on making the timeseries of a lake area. I wrote the following function which determines the NDWI first, then masks it and then calculates the area. I am getting stuck on ...
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Have multiple NDCI values at the same day in Time series chart (GEE)
I tried to generate the time series chart for NDCI to see the changes in 2017 but it shows multiple values for the same day. The chart looks so dense and ugly. How can I get the mean value for a month?...
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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 ...
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How to apply "where" condition for an image collection
I am trying to create annual wetted channel for multiple years which I have to do 3 noise removal steps after calculating MNDWI. But I realized that there is an error in the second step (minSize line ...
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NDWI for Sentinel 2 images containing clouds
I need some advice regarding NDWI and Sentinel 2 images containing clouds.
I need to apply NDWI to a Sentinel 2 image (S2B_MSIL2A) captured the next day of a weather event. In order to achieve it, I ...
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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 ...
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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 ...
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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:
...
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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 ...
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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 ...
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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 ...
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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. ...
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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 ...
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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 ...
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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 ...
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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?
user175462
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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 ...
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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....
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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 ...
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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 ...
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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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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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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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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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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 ...
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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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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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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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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-...
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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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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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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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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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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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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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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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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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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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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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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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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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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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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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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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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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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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