Questions tagged [ndvi]

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

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86 views

Whether Sentinel 3 OLCI can be used as a MODIS replacement for 250m NDVI?

Based on the bandwidths MODIS bands 1 and 2 (620nm - 876nm) will match S3 bands Oa7 - Oa17 (620nm - 865nm) I am just trying to know if anyone had any experience in using S3 data instead of MODIS for ...
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1answer
30 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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1answer
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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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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0answers
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
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
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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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
80 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
23 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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0answers
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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1answer
5k views

Reprojected MODIS NDVI has range from -32768 to 32767, expected -1 to 1

I'm new to StackExchange and to remote sensing. I am working with MOD13Q1 250m 16-day MVCs. My goal is to use NDVI time-series to classify cropping pattern and crop type, then link this data to ...
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0answers
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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0answers
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
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
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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0answers
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
64 views

AVHRR 1 km Coterminous US Server Location

I want to download a signficiant amount of AVHRR data directly from a FTP server... the problem is I'm having a really hard time finding the server location. I don't want to use EarthExplorer because ...
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2answers
606 views

Making stack from many images in Google Earth Engine?

Using the code below, I've computed 20 ndvi images for modis data. How can I stack and save them in a single file? var mod13 = ee.ImageCollection("MODIS/006/MOD13Q1") .filterBounds(geometry) ....
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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
50 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
65 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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1answer
631 views

Exporting an image of NDVI layers

I have calculated the NDVI for my study area. However, I am having challenges to export the NDVI images. I want to export a single image with several NDVI layers. I have tried the mosaic function but ...
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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
793 views

Performing per-pixel linear regression over multiple rasters with NoData?

I have a stack of 10 Landsat satellite images over the same area that I have calculated NDVI for. I want to calculate NDVI trend over time on a per-pixel basis. This means that for each pixel in the ...
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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
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
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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2answers
91 views

Computing NDVI in ArcMap from Landsat 8 “Analysis-Ready” Surface and TOA Reflectance Products

The internet is full of various contradictory advice on corrections one can make to get NDVI computed from Landsat 8 to fall between -1 and 1. This is for instructional purposes, so I hope to use ...
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1answer
91 views

How do I visualize NDVI values?

Currently, I have the NDVI values, and I transformed it from [-1, 1] to [0, 255]. Now my question is how do I visualize either of these value? My first thought is to make a color map similar to the ...
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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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2answers
1k views

NDVI analysis of LANDSAT 8 imagery in QGIS

I am trying to run an NDVI classification of 2015 multispectral LT8 imagery in QGIS to assess the quality of vegetation cover in regards to habitat suitability for a primate species in northern ...
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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
44 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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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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1answer
330 views

Filling gaps in NDVI time series? [closed]

I'm something of a beginner to remote sensing. I've got an NDVI time series, from 2002-2016. I've smoothed the data using an excel spreadsheet with the formula yt = (-2xt-3 + 3xt-2 + 6xt-1 + 7xt + ...
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1answer
143 views

Which output data type to choose in QGIS SAGA Raster Calculator in Batch Mode?

I have 5 years of MODIS13Q1 NDVI .tiff images for time series analysis. I want to multiply all the images with the scale factor of 0.0001 before using them. In order to process all at once I try to ...
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4answers
2k views

Alternative vegetation indices

I have been using NDVIs with limited success to identify trees in the central Great Plains region of the USA. The problem I have been encountering is that reflectance from farm fields/pastures have ...
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4answers
67 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
153 views

g.getOutputs is not a function while Creating a Chart from a Series

I created a Time Series of NDVI from Sentinel 2 Data, now I want to Chart it, using the following code. I get the error g.getOutputs is not a function I never used g.getOutputs, and from what I read, ...
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1answer
425 views

How do I convert Digital Number (DN) to reflectance in order to analyze NDVI

I'm working with a mapir nir + red camera meaning that its blue band captures nir light and its red captures red normally. I understand that NDVI is calculated using reflectance values. My question ...
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2answers
311 views

How to reduce number of raster bands of a RGB picture?

For my Master Thesis in Ecology I want to calculate an NDVI Index. The tricky part is, that I don't have sattelite pictures with bands and so on, but RGB pictures. The pictures where taken with a ...
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2answers
598 views

Maximum ndvi for 3 months average in Google Earth Engine

I have a ndvi series which I am able to plot using below code: var ndvi = l8.map(function(image) { return image.select().addBands(image.normalizedDifference(['B5', 'B4'])); }); var ndviChart = ui....
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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
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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3answers
233 views

MODIS temperature and NDVI data?

hope anyone could give me some hints here. I tried to download free MODIS data from their page(resolution 500m, 1km). Im interested in NDVI and temperature data. But when i load the hdf files into my ...