Questions tagged [ndvi]

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

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26 views

Extracting NDVI by regions defined by certain column using Google Earth Engine

I am trying to extract NDVI values by regions of a certain polygon shapefile. I need, as output a graph (or a table) where the regions are defined by a certain column, called 'FID_incend'. I need ...
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48 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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45 views

Creating NDVI time series from single polygon of shapefile using Google Earth Engine

I am new in Google Earth Engine, I am trying to plot ndvi timeseries from a single polygon of shapefile, but when I run the code I get "Error generating chart: Collection query aborted after ...
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139 views

Visualizing 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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33 views

Reduce.region odd result in GEE, however the map seems to be correct

I'm using Google Earth Engine to calculate the 5th and 95th percentiles of the intraannual coefficient of variation (CV) of the NDVI within a polygon (my area of interest). My code actually runs and ...
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53 views

Different NDVI in Python vs QGIS

When deriving NDVI out of a Sentinel-2 image - S2A_MSIL2A_20190502T074621_N0211_R135_T38SLF_20190502T102541 - I am getting a strange result when doing it in python vs in QGIS. In QGIS (using raster ...
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12 views

MODIS DAAC2Disk fails with “Unable to obtain ECHO token”

I have been using the tool DAAC2Disk to easily download NDVI using an extent. However recently the tool fails with the error: "Unable to obtain ECHO token" Has anyone encountered such error? Or know ...
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1answer
44 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
26 views

gdal_calc equation results in error: divide by zero

iIt is quite obvious to me that the rasterset A, B within the NDVI equation, --calc='"((A-B)/(A+B))"' with cell_value=0 will lead to the above error (division by zero). How can I avoid the error?
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491 views

Performing Radiometric Calibration of Sequoia Imagery?

I recently bought a used Sequoia camera and when I bought it, I was under the impression that the sun irradiance sensor and calibration plate would calibrate all my images in real time and I wouldn't ...
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1answer
33 views

Irrigated Area Recognition in Google Earth Engine

I'm using Google Earth Engine with the Python API. I have calculated the NDVI value over an area, set a threshold and the result is a layer where black areas exceed my NDVI threshold (don't pay ...
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58 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
150 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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1answer
38 views

NDVI chart of sampled points

I'm working with Sentinel 2 satellite and I have sampled on the map 4 blue points indicating an irrigated areas, and other 4 red points for non-irrigated ones. Then, I have considered 4 collections, ...
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198 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 ...
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1answer
48 views

Google Earth Engine: Use multiple bounding boxes to extract mean VI value

I am new to GEE with no prior Javascript knowledge. I am trying to find a way to use multiple bounding boxes (which are in bottom-left point x,y and top-right point x,y) from a csv file in order to ...
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17 views

Calculate the annual mean NDVI for a region using the Maximum Value Composite

I first used the Maximum Value Composite to generate a annual NDVI for a watershed, and then calculated the mena NDVI for the entire basin. I don't know if this code is correct. In addition, I want ...
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674 views

Analyzing stacked time series NDVI images in ENVI? [closed]

I just started playing around with stacking NDVI images from different years into one RGB value and am unsure how to read the photos or analyze them. The image on the left had R 2011 G 2011 and B ...
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1answer
515 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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1answer
703 views

I need to add a sentinel-2 image into Google Earth Engine Explorer with a specific ID

I'm new at Google Earth Engine and Javascript. I am using the graphical user interface of Google Earth Engine (Explorer) to obtain NDVI using sentinel 2. My study site is somewhere in Peru with an id:...
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33 views

Chart - trendlines - slope - NDVI - visibleInLegend: true - GEE

I am using the following code in GEE to calculate the trend line: ndviChart.setOptions({ title: 'NDVI (Sentinel 2)', vAxis: {title: 'NDVI'}, trendlines: {type: 'exponential', 0: {color: '...
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1answer
66 views

Arcpy reclassify with function

I have two rasters, one with NDVI values, and one with greyscale values (=(red band + green band + blue band) / 3). The rasters have the same name. I need to reclassify them in arcpy with the ...
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1answer
25 views

My NDVI values are way out of range - GEE

I am supposed to collect NDVI values for some states in the USA. I understand NDVI is supposed to be between -1 and 1, but my values are in the 1000s. Can someone please help me with the ...
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0answers
31 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 ...
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14 views

Problem merging/clipping MODIS rasters in QGIS

Im pretty new to QGIS and am having some trouble making a NDVI map for Mali. To cover the whole country I need 5 MODIS NDVI tiles, however every time I try to merge them I get a "the following layers ...
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21 views

Google Engine: Time Series Analysis with multiple point data [duplicate]

I have multiple points representing different crops for an area (say 100 per crop, and 5 types of crops). I compute the Sentinel2 NDVI for a period of one year. Even if I filter for just one type of ...
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2answers
592 views

GEE Export.image.toDrive output not matching bounding box?

I am new to GEE and javascript. Copy-pasting here and there, I managed to put together this code that extracts NDVI from cloud-free Sentinel-2 images on GEE. I created a fusion table from a KML with ...
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1answer
98 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 ...
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1answer
29 views

Using NDVI along with regular RGB and NIR bands for image classification

Is it plausible to use NDVI along with other regular bands for image classification related data processing? Recently, I came across a comment that RED and NIR band might interfere with NDVI or vice ...
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1answer
3k views

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

I am exploring Sentinel-2 time-series NDVI with Google Earth Engine. In another post (here) I calculated and exported NDVI values from Sentinel-2. Now I would like to create a NDVI time series chart, ...
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1answer
90 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
33 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
42 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
57 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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19 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
29 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
22 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
38 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
124 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
113 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
29 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
20 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
6k 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
41 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
27 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
102 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
22 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
12 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
66 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
758 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) ....