Questions tagged [ndvi]

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

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1answer
315 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 ...
2
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1answer
81 views

Is it rational to compare vegetation indices derived from different Landsat sensors?

I am using images from two different sensors, Landsat 8 OLI (January 2017) and ETM+ (January 2007) to compute various vegetation indices. These indices involve RED and NIR band to scale vegetation ...
2
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1answer
387 views

Calculating average NDVI for GPS coordinates using QGIS?

I have calculated the NDVI image and overlain GPS coordinates for a pack of wild animals over the top. I would like to calculate the average NDVI of all the GPS points, and then calculate the average ...
2
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1answer
165 views

Georeferencing image for EarthExplorer?

I am quite new to QGIS and I am trying to do something which seems so simple but it won't work. I have looked for an answer and couldn't find any. So I dowloaded data imagery from EarthExplorer about ...
2
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1answer
579 views

Splitting multiband raster into multiple bands using ArcGIS ModelBuilder? [duplicate]

I'm using the ModelBuilder functionality in ArcGIS, and would like to take a raster that contains 4 bands, clip it with a polygon and then make NDVI from the clipped file. To do that, I need access to ...
2
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2answers
209 views

Comparability of Landsats

I have collected data (spectral bands) from Landsat 4-5 and Landsat 8. I was calculating NDVI when I noticed that the two Landsats have different band numbers designated as Red and Near Infra Red (...
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
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1answer
392 views

PostGIS Raster performances

I ingested two Landsat images into PostGIS database using : raster2pgsql -I -C -s 28356 -M -t 100x100 LS7_20150425_B40.tif public.red | psql -d postgres -U postgres raster2pgsql -I -C -s 28356 -M -t ...
2
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1answer
330 views

NDVI in ENVI: Output format issue

I am working on NDVI in ENVI... the output file is in Envi Standard format... I required it in Envi Classification format, which can be done through Envi Edit Header tool... This requirement is for ...
2
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1answer
513 views

Failure in TIMESAT integral calculation

in short: My TIMESAT image-output of the seasonal parameter “Large Seasonal Integral” is wrong. TIMESAT continues to write a file with negative values (as 16 byte Integer) although Parameters should ...
2
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1answer
594 views

Calculating quantile values over a stack of images with grass gis. Help needed on r.series

I need to calculate the values for the 25%, 50%, 75% and 90% quantile over a series of rasters (time series of ndvi values from landsat). I am exploring the r.series command in Grass GIS, but the ...
2
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1answer
21 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:...
2
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1answer
321 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: ...
2
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1answer
464 views

Data smoothing of 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 I learned how to plot a NDVI time series chart. I know that there are many smoothing methods for reducing NDVI ...
2
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2answers
457 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 ...
2
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1answer
105 views

Aggregating/Averaging NDVI across pixels. Arithmetic mean seems bad choice

I need to compute an aggregate index for vegetation density in certain (large) shapes, to assess desertification. I have NDVI data at a high spatial resolution (~100 NDVI-pixels per aggregation shape, ...
2
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1answer
310 views

Troubleshooting downloading MODIS NDVI Data in R

I am trying to download MODIS Data from 2000-2018, however I am encountering some difficulties. Here is my script MODISoptions(localArcPath = "/Volumes/myserver/MODIS/data", ...
2
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2answers
1k views

Planet NDVI calculation: ModuleNotFoundError: No module named 'rasterio'

I'm performing NDVI calculation on a Planet Scope 4 band image as per Planet's documentation The following block of code is what I wrote: Extract band data from original image in working directory ...
2
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1answer
291 views

Landsat Collection 1 Level-1 or Landsat Collection 1 Higher Level?

I want to use NDWI and NDVI index in my study for a time-series analysis using all products available (Landsat 5,7 and 8). Can I use the product Landsat Collection 1 Level 1 for my analysis or ...
2
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1answer
89 views

NDVI usage for ArcCollector and Crop Yield

So my question is as follows: I am a GIS tech for a large vineyard management company. Every year a real struggle of ours is getting a crop estimation (with +- %15 accuracy, company wants it to be +-%...
2
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1answer
260 views

Why do UAV-derived NDVI values fall far outside -1 to 1 range after empirical line calibration?

This question was marked as being a duplicate of Landsat8 NDVI values not in the -1 to 1 range but I've posted my question because: I am not using Landsat; and there was no explanation of how to ...
2
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1answer
144 views

Is there a standard color palettes for the spectral indices?

Is there a standard color palette (or most commonly used in publications and other materials) for the spectral indices?
2
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1answer
267 views

How do you convert a raster of digital values of ndvi to an index of NDVI?

I have a raster of the Mean May Normalized Difference Vegetation Index (NDVI) that is a composited measure of VGT daily images, acquired between 2000 and 2009 in May, using the Mean Compositing ...
2
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1answer
238 views

GRASS 7 raster map calculator

I am new to GRASS and am trying to use it because I can't afford the Spatial Analyst extension in ArcGIS. I am trying to remove all of the values in a NDVI raster less than some value to exclude ...
2
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2answers
111 views

How to extract clear cut areas from dried trees in forests

I have 40 cm resolution aerial image with visible and near-infrared bands. Purpose is to extract dried trees in forest. I used multiresolution segmentation algorithm to extract individual trees and ...
2
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1answer
979 views

How to interpret Tasseled Cap Greenness for Landsat 5?

I have amassed a few promising literature articles, and looked at the help files for ENVI, ArcMap and PCI, and no one really goes into great depth on how to interpret spectral values for Tasseled Cap ...
2
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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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2answers
499 views

TIMESAT input image requirement?

I tried to work on TIMESAT but always facing a problem. Here is the method I have used. Seems correct, but I get a warning at the end. I have created a NDVI file from ENVI 4.8 >> Transform >> NDVI >...
2
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1answer
2k views

Calculate EVI From Landsat 8 in QGIS [closed]

I have calculated atmospherically corrected reflectance values for Landsat 8. From that, I am getting correct values of NDVI in QGIS, but for EVI I am not getting the correct values. For some images ...
2
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1answer
971 views

problem of using TIMESAT to processing MODIS NDVI

I want to use TIMESAT software to analyse time series MODIS NDVI data. Firstly, I use MRT tool to mosaic,subset and project MODIS NDVI data and output data as GEOTIFF format, and save as ENVI standard ...
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
22 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, ...
2
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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 ...
2
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1answer
68 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 ...
2
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1answer
131 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 ...
2
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0answers
225 views

Nonlinear regression in Google Earth Engine on each pixel in an image collection using GEE's servers

I am attempting to optimize the parameters for a double-logistic function on an annual MODIS NDVI time series in Google Earth Engine. I have previously looked at Non Linear Regression in Google Earth ...
2
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0answers
133 views

Calculating indices such as NDVI or NDSI on Landsat 8 imagery whose pixel type is 16 bit signed integer?

I am trying to calculate an NDSI (Normalized Difference Snow Index) using Landsat 8 OLI level 1 imagery atmospherically corrected in ERDAS ATCOR using raster calculator in ArcMap. NDSI is used to to ...
2
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0answers
227 views

NDVI calculation problem

I have photo created by UAV, and I want to calculate bNDVI: (NIR-blue)/(NIR+blue) I have these bands (filter is ok -100%). So using QGIS I have values -0,1-> 0,3 - but bNDVI must be from 0,65->0,...
2
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0answers
130 views

EVI2 values dont' come out -1 to 1? [closed]

I'm very new to remote sensing in general, and aren't sure if I've made an error. I've calculated EVI2 for a Landsat 8 and Sentinel 2 image. Both Top of Atmosphere. I've used Google Earth Engine to ...
2
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1answer
147 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 ...
2
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0answers
73 views

Overlaying point data with NDVI layer with raster output (not graph)

I have point data, which are animal burrows, and a NDVI raster layer that shows plant productivity. I want to overlay these layers and determine if vegetation productivity is higher close to burrows (...
2
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0answers
237 views

Supervised Classification Plugin QGIS: change input image; use another raster layer

I'm doing supervised classification on a sugar cane field for identifying vegetation, soil, and soil and litter. The plugin is only taking in the GeoTiff taken from the multispectral camera we used (...
2
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0answers
523 views

Pixel based Regression

I have 80 .tif files, and each pixel value represents NDVI. The whole stack of images is a time-series. I want to run a regression for each pixel using NDVI and time. I have tried to approach this ...
2
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0answers
78 views

Extract Mean Raster Value from multiple raster files into Excel

I have a series of non-orthorectified raster files containing NDVI information. I would like to extract the mean value from each raster so I can see a summary of each raster image name and the ...
2
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0answers
194 views

16-day-MODIS NDVI values seem to be wrong compared to my soil moisture ground data!

I'm using MOD13Q1 product of MODIS for estimation soil moisture. As I know, this product is made up of the maximum value of NDVI of each pixel over 16-day calculated NDVI values. The problem is that ...
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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0answers
249 views

Comparing/Correlating NDVI Rasters with other index Raster

So, I've created two rasters. One for NDVI and one for another index for surface water from the same orthorectified World-View 2 image. I can visually see how the indexes are inversely proportional. ...
2
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0answers
2k views

Interpreting NDVI value on water?

There is a surreal thing on my NDVI images. NDVI values on lake is ranging from -0.04 to 0.7. (The lake surrounded by forest and has freshwater). Theoretically, negative value of NDVI is correspond to ...
1
vote
1answer
59 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 ...
1
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1answer
162 views

Difference between types of Vegetation indices

I am currently comparing different types of Vegetation Indices, in this example I am using a NDVI formula and a TCARI formula. The NDVI result came out as expected with values ranging from +1 to -1. ...