Questions tagged [ndvi]

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

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7
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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 ...
2
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2answers
3k views

Writing code for monthly NDVI medians in Google Earth Engine?

My goal is to get monthly NDVI medians in Google Earth Engine. This helpful post got me started: reduce image collection to get annual monthly sum precipitation However, I am using Landsat (not MODIS)...
3
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1answer
2k views

Is atmospheric correction necessary when working with multi-spectral indexes?

When you are working with Landsat Level 1 data and calculate indexes, e.g. NDVI, NDBI, SAVI ..., do you calculate them using raw data (pixel DN value), or atmospherically corrected data (surface ...
3
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1answer
541 views

NDVI-time series with missing values

I have a Landsat-NDVI-time series from 2013 - 2017 with 23 observations per year (115 scenes in total). My goal is to get a smooth time series for a selected single pixel (maybe by using a Savitzky-...
2
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1answer
2k views

Using Loop for calculating NDVI in R?

I am using MOD09Q1 now and I would like to calculating NDVI whole year data. One year, I have 46 band 1 images and 46 band 2 images. list.files I creating list of band 1 and list of band 2. ...
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2answers
620 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) ....
2
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0answers
400 views

QGIS 2.4.0-Chugiak: How to produce raster colour map

By carefully deriving the NDVI values from Landsat Band 3 and Band 4 after doing atmospheric correction by applying DOS1 method in semi-automatic classification Plugin QGIS, I was to calculate the ...
2
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1answer
2k views

Tutorial Vegetation Condition Index

Anybody here can help me regarding calculating Vegetation Condition Index (Kogan,2004) for Landsat?. Specially facing problem in NDVI_max and NDVI_min; which should be maximum and minimum value?
0
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1answer
870 views

Changing the the range for MODIS NDVI

I need to get MODIS NDVI (MOD13A3), but output from EarthExplorer or Daac2Disk HDF format is a numerical range is -2000 to 9996. But I need for futher work basic range -1 to 1. Is there any ...
3
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2answers
603 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....
2
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2answers
2k views

NoData Value = 0, problem when creating NDVI, Erdas

I try to create an NDVI from Landsat and ASTER satellite images using Erdas Imagine. In Erdas, the satellite images have a nodata value of 0. After creating an NDVI, the nodata value is still 0, but ...
2
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1answer
946 views

Calculating NDVI per region, month & year with Google Earth Engine?

I want to calculate the mean NDVI per region (admin level 3, also called woreda), month and year. So my end result would look something like this: regions year month NDVI ------------------...
1
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1answer
79 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 ...
1
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1answer
1k views

Mask clouds in LandSat 8 surface refletance image

I would like to know how to remove the clouds in a ImageCollection of LandSat 8 Surface Reflectance (SR) image and create a single image without clouds using google earth engine, to calculate NDVI. I ...
-2
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1answer
199 views

Looping for NDVI in different file paths using R? [closed]

I have different bands separated in different file directory. I used Raster Calculator to calculate NDVI using "NIR1.tif"-"RED1.tif"/"NIR1.tif"+"RED1.tif" as formula. The link below describes a loop ...
16
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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 ...
3
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5answers
6k views

Creating a Time series NDVI map

I would like to create a NDVI Time Series map? How do I do that? The one I probably would like to have similar like this http://proceedings.esri.com/library/userconf/proc02/pap0593/p05931.jpg I ...
7
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2answers
9k views

Performing regression analysis between two variables using ArcGIS Desktop?

I have a temperature image (interpolated from climatic point data) and NDVI data at the monthly interval. I need to do correlation analysis between temp and NDVI. Is it impossible to do this using ...
3
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2answers
637 views

SPOT NDVI time series

I have 423 spot.vgt ndvi from first April 1998 till 31 Dec 2009. I want to know how to stack these NDVI to have one image for time series analysis? Or better to ask how is it possible to analyze a ...
3
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1answer
3k views

Extracting LANDSAT time-series data by polygon using Google Earth Engine?

importing the landsat 5 TM 32-day NDVI composite data set. I have made it as far as drawing a polygon of my ROI and extracting from a different data set, a global land cover map (ESA/...
3
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1answer
467 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 ...
3
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1answer
2k 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, ...
2
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3answers
1k views

Where to obtain free 15m ASTER image for New Mexico?

I am looking for a free Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) image that will let me to perform NDVI for the pilot crop health/soil moisture that can go as far back ...
2
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1answer
230 views

Image Collection Statistics in Google Earth Engine?

How can I extarct mean of each image collection in google earth engine? for example for this code: var modis = ee.ImageCollection("MODIS/006/MOD13Q1") .filterBounds(geometry) .filterDate("2000-01-01",...
2
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1answer
445 views

Using ASTER for time series analysis?

This is a follow up to Where to obtain free 15m ASTER image for New Mexico?. If I want to analyze 10 years or so, do I need to download each ASTER file for each year (e.g. 2003 ASTER, 2004 ASTER,...)...
2
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1answer
1k views

How to remove clouds with the cf_mask.tif file provided from landsat 8 surface reflectance data?

I just downloaded my first group of landsat 8 surface reflectance data files. In this package contains sr bands 1-7 (I hope to use some of these to create an NDVI) as well as numerous files called: ...
2
votes
1answer
313 views

Why getting wrong NDVI values resulted from scaled reflectance in ArcMap?

I have made atmospheric corrections to my Landsat 8-OLI raster using 'ENVI FLAASH' having surface reflectance values scaled between 1-100. In ArcGIS I am using simple expression to compute NDVI ...
1
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3answers
1k views

How to create several header files to open AVHRR NDVI3g (GIMMS) files?

I have downloaded GIMMS NDVI3g data from http://ecocast.arc.nasa.gov/data/pub/gimms/3g/ I now need to open the files in arcgis. I have the follwing GRID PARAMETERS: grid-name: Geographic Lat/Lon ...
1
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1answer
942 views

How to get “p value” for time series data to detect significant change

I have yearly maximum NDVI data (1982-2008) and extracted all value to Excel. Also calculated slope value for each point during the 27 years. All of you know the slope value represents changes per ...
1
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1answer
256 views

DOY chart in Google Earth Engine

With the following code I am trying to produce a NDVI graph with the days of the year on the x axis (based on this example, 2nd graph). var modisNDVI = ee.ImageCollection ('MODIS/MCD43A4_006_NDVI'); ...
4
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1answer
375 views

Black vertical lines on exported image from Google Earth Engine

I tried to export the NDVI obtained from the Landsat 8 Surface Reflectance Collection in Google Earth Engine and I keep on getting black lines in my final export. Everything looks fine when displaying ...
4
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2answers
465 views

Using Landsat 5 TM 8-Day NDVI Composite?

I'm working in a project where I need the NDVI for some areas from Uruguay for the period 1988-1993, and I found this product "Landsat 5 TM 8-Day NDVI Composite" but I'm not sure of how it was ...
3
votes
1answer
434 views

QGIS raster calculator: difference gives NaN for Landsat 8 scene

I'm strugling with the QGIS Raster Calculator, trying to get a NDVI image from a Landsat 8 scene (path 222, row 84, date 2015-11-15). The problem is, I'm consistently getting NaN values for all the ...
3
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3answers
2k views

NDVI image value changes from -1 to 1 in ENVI to 0-255 in ArcGIS Desktop and ERDAS Imagine?

When i open NDVI image in ENVI, its value is still within the range (-1 to 1). But when I open this NDVI image in ERDAS and ArcGIS Desktop, its value is 0-255. What does it mean? Is the NDVI ...
3
votes
1answer
2k views

Mask clouds in an ImageCollection google earth engine

Is It possible to create .median() Surface Refletance image (landSat 8 RS) without clouds before calculating the NDVI in goolge earth engine? I need to work with a year (eg. 2016-01-01, 2016-12-31), ...
2
votes
2answers
1k views

NDVI derived from Landsat band 3 and band 4 using QGIS raster calculator shows the different range when opening in the ArcGIS

I have calculated Normalized difference vegetation indices from landsat 5 band 3 and band 4 that have 0-0.38 minimum and maximum ranges respectively. But whenever I open the same NDVI.tiff file in ...
2
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1answer
150 views

Calculate mean values for all bands and date to a dataframe

I have 5 rasters, each having 10 bands, where each band corresponds to a specific date. How do I calculate mean values for all 10 bands and save them? I need to save the mean values in a dataframe ...
1
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1answer
105 views

Is it possible to create one single NDVI image out of multiple NDVI images?

I am working with Landsat 8 images to create seasonal NDVI images in QGIS. For all NDVI images I masked the clouds/cloud shadows so there are 4 different NDVI images with different cloud/cloud shadow ...
1
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0answers
194 views

Why are Landsat-8 derived NDVI values higher than SAVI values?

I have calculated NDVI and SAVI vegetation indices for a landsat-8 image. I am unexpectedly getting higher values for the NDVI than SAVI. What may be causing these unusual results? NDVI=0.46 SAVI=0....
1
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2answers
3k views

Extract pixels from NDVI in ArcMap

I have a NDVI that I created from a Landsat 5 image. Is there a way to extract all the pixels above a certain threshold and save it as a shapefile? I am trying to create a vegetation mask of sorts to ...
0
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0answers
272 views

Stretching (rescaling) Raster (NDVI) Values between -1 and 1?

I am trying to equalize NDVI values for the same area temporally. For example 2014 LS8 NDVI values between -.12 and .007 while 2011 LS5 values between -.33 and.77. I would like to equalize each raster ...
0
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2answers
992 views

Landsat8 NDVI values not in the -1 to 1 range

I was trying to create an NDVI from Landsat8 OLI image from July 2013. I ran DOS1 and TOA. The values range up to 3. The original files were downloaded from EarthExplorer(EE), ran on QGIS and ...