Questions tagged [ndvi]

Normalized Difference Vegetation Index is used to quickly identify vegetation and its condition in remotely-sensed data.

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31 views

ArcPy: Create NDVI with Raster Calculation and Map Algebra

My target is to create NDVI Rasters but I'm stuck with python loops, since I'm new to that, so sorry for a maybe basic question. I have 2 folders, one with rasters (tif) with the red band, the other ...
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29 views

Duplicate NDVI measurements on Graphs in Google Earth Engine

I have created the following code below for graphing the NDVI at areas of interest and printing it to the user interface. The problem I am having is that on the same date there are two different NDVI ...
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22 views

Reconstruct NDVI time-series applying Savitzky-Golay Filter with Python/Numpy [closed]

I want to smooth/reconstruct a NDVI time-series applying Savitzky-Golay Filter with Python/Numpy. I have the NDVI time series data in a CSV format. How can I perform this smoothing of the time series ...
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14 views

I am trying to create an NDVI image using an RSGISLib python script, but it is displaying no data values

My script runs fine and creates an output, but the output is displaying values all the way down to -999, rather than just having the values present in the NDVI result (0-1). I can create an NDVI image ...
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1answer
18 views

Image analysis about area

I tried to find out the lake's area in an image raster - I used NDVI and reclassify then I got a whole value file like this. Is there anyone can tell me how to divide them to each polygon? Or I can ...
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15 views

Scaling factor for MODIS (MY09GA 006 or MYDTBGA 006) product for timeseries data

I was using Modis data (MYDO9GA) product for my research and I was following this document as a user guide. https://landweb.modaps.eosdis.nasa.gov/QA_WWW/forPage/user_guide/MOD09_UserGuide_v1.4.pdf ...
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25 views

Calculating NDVI values for specific zones using zonal statistics using QGIS

I am currently working with multispectral data from a MicaSense RedEdge M on a plot size study in wheat research plots. I want to conduct zonal statistics to calculate NDVI for individual plots. I ...
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19 views

Reading value and coordinates of every pixel post NDVI calculation in ArcGIS Desktop?

I have a pre forest fire image and a post forest fire image. I would like to make a comparison between the coordinates and the values of both images pixel by pixel. How would I access the value and ...
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10 views

Rescaling NDVI from 0-255 to -1-1 in ArcGIS Pro?

My NDVI raster ranges from 0-255. My goal is to get values from -1 to 1. If using the Raster Calculator, what would be the correct equation to achieve this? I'm working in ArcGIS Pro.
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1answer
46 views

Calculating statistics for multipolygon in Google Earth Engine?

I have a shapefile which contains many crop plots, around 2000. I need to calculate NDVI (normalized difference vegetation index) and then calculate statistics for each one of the 2000 plots ...
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25 views

Finding whether a particular band value is consistently less over a period of time in an image collection

The code below gives me forest regions of India from the Hansen data set and then I have filtered the landsat images of these regions from 2013-2019 on a quarterly basis. My output image is such that ...
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1answer
52 views

Time series analysis of NDVI

I want to create a chart of annual NDVI for a specific region. The output should be one NDVI value for that region for each year. I tried the following code and so far was able to get an image ...
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1answer
66 views

Pixel wise NDVI calculation in GEE

I have a collection of Landsat images filtered over forest regions of India over a time interval of 6 years(2013 - 2018). I have again filtered this collection such that I have one image per 4 months, ...
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2answers
29 views

Visualize Image Collection

I have created image collection in GEE of LANDSAT 7 NDVI (LANDSAT/LE07/C01/T1_8DAY_NDVI). I chose date range and I know I have 71 images in the image collection. Is there any way to clip all the ...
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1answer
20 views

Fusing Collection 1 Landsat 7 and 8 Surface Reflectance NDVI

I'm fusing L7 & L8 surface reflectance into an NDVI time-series. I'm using the method described in Roy et al. 2016 to convert L7 NDVI to L8 NDVI using a simple regression equation found in table 3:...
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1answer
24 views

Format GeoJSON use Join method before export in Earth Engine

After filter an LANDSAT-05 for an small area var Collection = function(pixel) { var colForPixel = ee.ImageCollection('LANDSAT/LM05/C01/T1') .filterBounds(pixel) .filterMetadata('CLOUD_COVER','...
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1answer
37 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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1answer
30 views

Dictionary.toArray: Unable to convert dictionary to array, key 'NDVI' has a null value

I am trying to reduce a region by clipping an image from copernicus to get NDVI and then calculate a Kc value. However, Once I use a polygon I imported with the "Draw a Shape" tool, the calculations ...
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1answer
31 views

NDVI in landsat image not in range(-1,1)

Using ENVI 5.3. I have done a radiometric calibration(radiance) and flaash atmospheric correction then a seamless mosaic and subsetted data from ROI. I then calculated the NDVI. My results in May 2017 ...
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1answer
78 views

Pixel-based NDVI time series - Google Earth Engine

I am a newcomer using GEE and now I want to do a NDVI time series. The condition is that it must be based on the result of the pixel, and it need to displayed on the map. I just made the NDVI time ...
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1answer
109 views

Finding monthly NDVI anomalies in Google Earth Engine?

I am using 16 NDVI data from GIMMS 3rd generation, and I wish to somehow visualize monthly anomalies (Difference from long term means greater than .5). I have plotted a time series of the data running ...
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1answer
47 views

Raster Statistics in GEE

I have created many rasters in Google Earth Engine that represent the NDVI. I want to apply statistics on them. I want to count how many pixels I have in every raster, and then I want to count how ...
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1answer
53 views

Interpolate the gaps among NDVI values [closed]

I want to calculate the Crop Water Requirements and for this I need NDVI values for a period of time. Because I have Sentinel 2 images and the temporal resolution is 5 days, I need also the values ...
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1answer
37 views

Access layer of raster stored in memory using ArcPy to create NDVI from subset of multi-band raster

I am trying to create a final output of an NDVI raster for a number of Landsat images run through a for loop in Python 3 (for ArcGIS Pro). I am able to produce the NDVI rasters when I save the ...
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1answer
78 views

Smoothing/interpolating across images in an ImageCollection to remove missing data

I have some code that is working properly to calculate the monthly NDVI averages for the previous two years from a date but I sometimes have missing data in some of the months and I would like to get ...
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39 views

Make a loop in Google Earth Engine for reduce NDVI from year a months?

I have this code, it generate N ImageCollection and for each image a chart from NDVI in function a the months This is the place of study: var areaEst = ee.FeatureCollection("users/aleszczuk/...
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1answer
32 views

NDVI time series chart showing multiple values for the same point in Google Earth Engine

I tried to generate a time series chart of NDVI using Sentinel-2 data for multiple points. But the chart has vertical plots with two values for same point and same date. Here is the code: var ...
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1answer
64 views

Getting NDVI data only for March from 2000-2003 using Google Earth Engine? [duplicate]

I have a polygon and I want to calculate its mean NDVI values from 2000-2003 (and few more periods) but only for March so the final result should be image which contains the mean NDVI values only for ...
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1answer
45 views

Citing greenest pixel composite images derived from Google Earth Engine?

I am using two greenest pixel composite images via Google Earth Engine for a project but am unsure how to cite this data. Do I cite it as regular Landsat data?
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4answers
68 views

Determining NDVI of polygon using ArcGIS Desktop?

I have calculated the NDVI of a city. Now I want to know how "green" every street segment in that city is. I therefore buffered 7.5m on every street segment. I then used the Zonal Statistics as a ...
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1answer
61 views

Convert Landcover Raster to Vector to Use for Tracking NDVI Over Time

I want to look at NDVI and other spectral indices over time and compare these time series across different land cover types. I believe I have the code to do this but I'm running into the error that I ...
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1answer
67 views

Differences and thresholdis of ImageCollection in GEE

I have the following code (very basic as I am new user), and I want to create an NDVI difference collection by subtracting every NDVI image from my initial collection, with its previous one (something ...
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0answers
73 views

R MODIS MOD13Q1 - How to handle data quality issues?

I'm running into some issues with 250m 16-day MOD13Q1 NDVI data using the MODIS package in R. Looking at the following raster plot, there are certain days where the NDVI does not match the true ...
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1answer
188 views

Rasterio.features.rastersize

I have to transform the list of polygons that is in vector form into a raster mask that should be geographically aligned with the NDVI image that I have. I was advised to use rasterio.features....
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2answers
168 views

Google Engine - Make a greenest pixel composite for Sentinel 2

Does anyone know how to do a composite of greenest pixel for Sentinel 2? That is calculate the maximum NDVI for a Image collection, and then do a pixel-wise image stacking of the original bands (...
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16 views

Error in compareRaster(rasters) : different extent

I'm having this error in NDVI tif layers, however, all the layers have the same extent and resolution. The only difference is an elevation layer (Aster_DEM_UTM).
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1answer
336 views

Earth Engine landsat 8 NDVI Time Series// multiple daily data points

When charting a time series based on Landsat 8 NDVI data over the course of yearly increments inside a polygon, the charts that I get have multiple data points on singular days. I've tried to reduce ...
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105 views

Growing Season Length in Google Earth Engine?

I am trying to estimate growing season length with the MCD12Q2 dataset (Land Cover Dynamics Yearly L3 Global 500 m), which includes dates for the start and end of the growing season (...
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39 views

Landsat 8 Mosaic (NDVI) Overlapping?

I have downloaded 3 satellite images (Landsat 8 OLI TC1P), in three different periods (two images are from Mart 4. 2017. and the one is from Mart 20. 2017). I have joined (made mosaic) them in ENVI ...
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1answer
82 views

GEE - Add image band (NDVI) from one ImageCollection to corresponding image in an other ImageCollection

I have two ImageCollections one from Sentinel-1 and the other from Sentinel-2. From S-2 i derive the NDVI. I want to add the NDVI band from the S2 Collection to the Sentinel-1 ImageCollection with the ...
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1answer
94 views

problem with sentinel-2 NDVI export to TIFF in Google Earth Engine

I'm trying to calculate and export NDVI rasters extracted from Sentinel-2 using the script: https://code.earthengine.google.com/a9247db3f03e9514eb0378d1f59e9447 Source code: Export images in google ...
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1answer
248 views

Create animation of NDVI from ImageCollection in GEE

I'm trying to make an animation of NDVI images from sentinel collection in order to see clearly variance in the field. The first part of the code works with little error: "Layer name is not a string: ...
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1answer
27 views

Merging NDVI classified and unsupervised classified image?

I have clipped forest area from an image and apply NDVI classification on forest area and in the remaining, I have done unsupervised classification. So, I want to know after NDVI and unsupervised ...
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1answer
140 views

Counting number of pixels with negative NDVI value within polygon using Google Earth Engine?

I have made a map of vegetation loss and gain for a polygon in Google Earth Engine using NDVI and would like to calculate the area where loss occurred. I attempted to use the reducer to get the sum of ...
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1answer
291 views

Make a Loop for Monthly NDVI in Google Earth Engine?

I've computed maximum NDVI for each month. but I don't know how can I write this code through a loop in Google Earth Engine? code link: https://code.earthengine.google.com/...
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1answer
90 views

Can I use a greenest pixel or a no clouds Sentinel 2 for NDVI analysis?

Can I use a greenest pixel or a no clouds Sentinel 2 for NDVI analysis? I want to use it for extract spectral signature. And now that I´m asking about it, I want to know if I can work classification ...
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18 views

Atmospheric correction using ERDAS 2014

There are some questions about atmospheric correction using ERDAS. Is it possible to use the atmospheric corrected satellite image to calculate NDVI and LST using ATCOR of ERDAS? If not, I wonder if ...
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1answer
116 views

NDVI index based on QA bands for MCD43A4 , in GEE

I want to calculate the NDVI index based on the MODIS/006/MCD43A4 collection and based on quality bands, but as a new GEE user I have no idea If I am on the rght way to do this. So far I have the ...
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1answer
49 views

More information about GEE dataset needed

I have a rather basic question, in relation to the MCD43A4 006 NDVI dataset in GEE. I am aware of the methods used for the generation of the BRDF MODIS dataset, but I would like to know more details ...
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1answer
191 views

Perform Radiometric Correction of Landsat images using ArcGIS Desktop

I need to run NDVI on a study area that is covered by more than one Landsat image. The NDVI must also be run over numerous years using different Landsat sensors (eg: Landsat 7 Level 1, Landsat 4-5 ...