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
21 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, ...
3
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1answer
761 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
40 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
18 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 ...
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 ...
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1answer
26 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
24 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
53 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
41 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 ...
3
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2answers
79 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
61 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
24 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
49 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
31 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
29 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
51 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
294 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
142 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 ...
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 ...
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4answers
65 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
126 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
348 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
296 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
519 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
45 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
84 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
52 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 ...
2
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3answers
224 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 ...
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2answers
149 views

Classification model using NDVI time series?

I am trying to form a classification model with the help of NDVI time series data. I want to use methods like SVM and Random Forest. I know how to apply these methods to normal data. But, I am ...
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1answer
392 views

Resampling 30 m NDVI to 5 m in ArcGIS [duplicate]

Is there any easy way to resample 30 meter NDVI from Landsat 8 images to 5 metres? I use raster to point and the interpolation of point to raster using Kriging method. I know that it may not be a ...
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1answer
61 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 ...
3
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1answer
59 views

Differences and thresholdis of ImageCollection in GEE

I have the following code (very basic as I am new user), and I want to create an NDVI difference collection by subtracting every NDVI image from my initial collection, with its previous one (something ...
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1answer
73 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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0answers
54 views

R MODIS MOD13Q1 - How to handle data quality issues?

I'm running into some issues with 250m 16-day MOD13Q1 NDVI data using the MODIS package in R. Looking at the following raster plot, there are certain days where the NDVI does not match the true ...
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1answer
103 views

Rasterio.features.rastersize

I have to transform the list of polygons that is in vector form into a raster mask that should be geographically aligned with the NDVI image that I have. I was advised to use rasterio.features....
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1answer
1k views

Rescaling NDVI values 0-255 to [-1;1] using ArcGIS Raster Calculator?

How do I rescale NDVI values that are 0-255 to -1;1? I'm trying to do it in ArcGIS Desktop.
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1answer
26 views

Merging NDVI classified and unsupervised classified image?

I have clipped forest area from an image and apply NDVI classification on forest area and in the remaining, I have done unsupervised classification. So, I want to know after NDVI and unsupervised ...
0
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1answer
58 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
107 views

Google Engine - Make a greenest pixel composite for Sentinel 2

Does anyone know how to do a composite of greenest pixel for Sentinel 2? That is calculate the maximum NDVI for a Image collection, and then do a pixel-wise image stacking of the original bands (...
1
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1answer
193 views

Earth Engine landsat 8 NDVI Time Series// multiple daily data points

When charting a time series based on Landsat 8 NDVI data over the course of yearly increments inside a polygon, the charts that I get have multiple data points on singular days. I've tried to reduce ...
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0answers
16 views

Error in compareRaster(rasters) : different extent

I'm having this error in NDVI tif layers, however, all the layers have the same extent and resolution. The only difference is an elevation layer (Aster_DEM_UTM).
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0answers
75 views

Growing Season Length in Google Earth Engine?

I am trying to estimate growing season length with the MCD12Q2 dataset (Land Cover Dynamics Yearly L3 Global 500 m), which includes dates for the start and end of the growing season (...
0
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0answers
36 views

Landsat 8 Mosaic (NDVI) Overlapping?

I have downloaded 3 satellite images (Landsat 8 OLI TC1P), in three different periods (two images are from Mart 4. 2017. and the one is from Mart 20. 2017). I have joined (made mosaic) them in ENVI ...
2
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1answer
150 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: ...
4
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4answers
3k views

Where to download 4-band NAIP imagery for California?

I've been trying to find orthoimages with 4 bands for a couple of counties in California. I managed to download some from the GeoSpatial Data Gateway from the USDA (NRCS), but they all only have 3 ...
3
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2answers
135 views

Google Earth Engine: how to select NDVI for some land cover type

I am quite new to both Google Earth Engine and JavaScript. My goal is to obtain the NDVI just for some region (some polygon) only in the selected cover type. I managed to compute areas and number of ...
2
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1answer
79 views

NDVI index based on QA bands for MCD43A4 , in GEE

I want to calculate the NDVI index based on the MODIS/006/MCD43A4 collection and based on quality bands, but as a new GEE user I have no idea If I am on the rght way to do this. So far I have the ...
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1answer
100 views

Counting number of pixels with negative NDVI value within polygon using Google Earth Engine?

I have made a map of vegetation loss and gain for a polygon in Google Earth Engine using NDVI and would like to calculate the area where loss occurred. I attempted to use the reducer to get the sum of ...
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1answer
180 views

Make a Loop for Monthly NDVI in Google Earth Engine?

I've computed maximum NDVI for each month. but I don't know how can I write this code through a loop in Google Earth Engine? code link: https://code.earthengine.google.com/...