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15 votes
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Creating Sentinel-2 NDVI time series chart in Google Earth Engine?

You are using the variable NDVI to compute the chart, but this variable is a single image, because you applied median(). If you want a time series plot you have to compute the chart using the NDVI ...
HMSP's user avatar
  • 1,657
14 votes

Writing code for monthly NDVI medians in Google Earth Engine?

For the record, here is a good way to do this: var imageCollection = ee.ImageCollection("LANDSAT/LT05/C01/T1"); var months = ee.List.sequence(1, 12); var composites = ee.ImageCollection.fromImages(...
Nicholas Clinton's user avatar
9 votes

EVI and NDVI range value

You are right: the range of the NDVI is limited to values between -1 and 1 due to its' normalization properties. The negative limit of -1 will be reached if you encounter maximal reflectance (1) in ...
gurgli's user avatar
  • 176
9 votes
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Which NIR bandwidth is suitable to Calculate NDVI?

Between 770 and 1040 nm, you are nearly on a plateau in term of reflectance from the green vegetation (in fact, it decreases a little bit when the wavelength increases), so your green vegetation NDVI ...
radouxju's user avatar
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8 votes
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Using a fixed palette range to plot an NDVI raster in R

You need to supply levelplot() with a bit more information, via its at= argument, so that it can know the set of intervals to which you want the colors in col.regions applied. library(rasterVis) ## ...
Josh O'Brien's user avatar
8 votes
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Making stack from many images in Google Earth Engine?

You just need the function 'toBands()' and apply that on the image collection. Unfortunately, the function cannot deal with similar band names (at least, for your MODIS collection: it works fine for ...
Kuik's user avatar
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7 votes
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Extracting LANDSAT time-series data by polygon using Google Earth Engine?

The code that you copied uses an Earth Engine object of type "Image", and Image objects have a method/function named clip. Your reworked code (i.e. Landsat) uses an Earth Engine object of type "...
Tyler Erickson's user avatar
7 votes
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Why is a normalized parameter involving the Green band and Red band not used for Vegetation determination?

The best explanation I came across is this: the ratio of the difference of the red and infrared radiances over their sum as a means to adjust for or “normalize” the effects of the solar zenith ...
whyzar's user avatar
  • 12.1k
7 votes
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Why vegetation index, NDVI or SAVI is not working in the desert?

The sensitivity of the normalized difference vegetation index (NDVI) to the soil background and atmospheric effects has generated an increasing interest in the development of new indices. The NDVI ...
Maxima's user avatar
  • 1,701
7 votes
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Smoothing/interpolating across images in an ImageCollection to remove missing data

You can replace the values using where(). // Replace masked pixels by the mean of the previous and next months // (otherwise, how to deal with the first images??) var replacedVals = composites.map(...
Kuik's user avatar
  • 10.1k
7 votes

Problem generating NDVI chart in GEE

You are using an image property that does not exist. Use system:index instead of system:time_start. // Chart a single year mean of SB var TS1 = ui.Chart.image.series(modisNDVI, geometry, ee.Reducer....
HMSP's user avatar
  • 1,657
7 votes
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Rescale NDVI (-1:1) to 0-255 using R

SOLVED using rescaleImage() function in RStoolbox: library(RStoolbox) ndvi <- rescaleImage(x= ndvi, xmin = -1, xmax = 1, ymin=0, ymax=255) Now I get the expected results: ndvi class : ...
sermomon's user avatar
  • 994
6 votes
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landsat NDVI time series plot in R, based on point or pixel

Do you want an interactive map, or are you fine with plotting the NDVI timeseries for one (or few) specific points? In the latter you raster::extract() the NDVI-Stack values under your points, and use ...
Jeremy's user avatar
  • 366
6 votes
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Calculating Landsat 7 NDVI images using QGIS

Testing and comparing a Landsat 7 image (different area to yours, but same sensor data) reveals that the values are in fact both "correct". You (and I) have fallen into the trap of the Raster ...
Phil G's user avatar
  • 723
6 votes
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Viewing bands of landsat 8 images in QGIS for NDVI calculation?

You have downloaded the data and you can find it if you unpack the .tar.gz file using 7zip or similar software for unpacking files. The .tar.gz file is the fourth file from the top that can be seen in ...
Mikkel Lydholm Rasmussen's user avatar
6 votes

Arcpy reclassify with function

This is how I would do it (it requires the Spatial Analyst extension which I think you have): import arcpy from arcpy.sa import * arcpy.CheckOutExtension = "Spatial" ndvi_raster = Raster("...
umbe1987's user avatar
  • 3,785
6 votes
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Calculating NDVI

Start the filename of the output raster with a character not a number, i.e NDVI_1988_1 instead of 1988_NDVI_1 From the Esri FAQ: What characters should not be used in ArcGIS for field names and table ...
user2856's user avatar
  • 67.1k
5 votes

Obtaining something like NDVI value from Sentinel-1 product

Um, the Sentinel-1 sensor is C-band SAR (radar) data, not spectral. Given that NDVI is a spectral index of photosynthetically active radiation using the ratio between Red and NIR spectra, what makes ...
Jeffrey Evans's user avatar
5 votes

Pixel-wize trend analysis of an irregular time series stack of NDVI rasters in R

I guess I found a way to my own problem: Basically, I parsed the time variable from the filename and added it back to regression model. Below is the peice of code I used. library(raster) all <...
FlyingMGET's user avatar
5 votes

Mask clouds in LandSat 8 surface refletance image

The Surface Reflectance products contain a band called 'cfmask' and 'cfmask_conf'. The documentation tells you that all pixels labelled 4 in the first band are clouds. If you just want to mask clouds ...
Kersten's user avatar
  • 9,917
5 votes
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Do clouds reflect NIR/Red bands

Yes, it affects the values of NDVI, and it may not give the desired results sometimes. Information from Wikipedia: Normalized Difference Vegetation Index provides some details about the effects of ...
ahmadhanb's user avatar
  • 41.1k
5 votes

Calculate NDVI using ArcPy Spatial Analyst

I presume you're using ArcGIS Desktop which uses python 2x, not ArcGIS Pro which uses python 3x. Side note: this is one example of why it's important to specify the software you are using. In python ...
user2856's user avatar
  • 67.1k
5 votes

Difference between types of Vegetation indices

Not all indices are from -1 to 1. For example, REP (red-edge position) index could start near to 600 and end near to 800 nm. In the other hand, for any Normalized Difference Index, you can expect to ...
aldo_tapia's user avatar
  • 13.7k
5 votes

Purchasing NDVI imagery for South Western England?

I don't think this is the answer you're looking for but with the specifications you describe, unless there is a subscription through which the farmers need to finance imagery purchase, it would ...
Gabriel's user avatar
  • 3,155
5 votes
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Google Engine - Make a greenest pixel composite for Sentinel 2

You can use qualityMosiac exactly similar for Sentinel-2 as for Landsat. The method you are looking for is described here. What you need is adding a NDVI band to the image collection of Sentinel-2 ...
Kuik's user avatar
  • 10.1k
5 votes

Rasterio.features.rasterize

shapes : iterable of (geometry, value) pairs or iterable over geometries. `geometry` can either be an object that implements the geo interface or GeoJSON-like object. A list, tuple, or ...
mikewatt's user avatar
  • 5,103
5 votes
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Time series analysis of NDVI using Google Earth Engine

ui.Chart.image.series defaults to plotting system:time_start on the x-axis, which your dataset does not contain. You can use the optional argument xProperty to specify another parameter to use as x-...
phloem's user avatar
  • 4,688
5 votes

Getting NDVI values into .csv format using Python

There would be many was to do this, the method I use is to write my CSV file directly: with open("C:\\Users\\ARSH\\Desktop\\ndvir.csv",'w') as WriteCSV: for ThisRow in array: WriteCSV....
Michael Stimson's user avatar
5 votes
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Adding time as 'year' band to image collection

You can edit the metadata to specify a start time when you upload an image: Or you can edit it after upload, but after you open the asset info dialog, make sure to click the “Edit” toggle button to ...
Kevin Reid's user avatar
  • 10.4k
5 votes

Image.glcmTexture: Only 32-bit or smaller integer types are currently supported

The NDVI has values from -1 to +1. You can also use the following to generate a 8bit NDVI: // Rescale NDVI [0-255] var iv = il2014.select('NDVI').unitScale(-1, 1).multiply(255).toByte();
sermomon's user avatar
  • 994

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