Questions tagged [ndvi]
Normalized Difference Vegetation Index is used to quickly identify vegetation and its condition in remotely-sensed data.
407
questions
2
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1answer
25 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, ...
1
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0answers
12 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 ...
-2
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1answer
45 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 ...
0
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0answers
21 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: '...
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 ...
0
votes
1answer
28 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 ...
0
votes
1answer
21 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 ...
1
vote
0answers
23 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 ...
1
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0answers
13 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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0answers
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 ...
0
votes
1answer
82 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 ...
1
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1answer
25 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 ...
1
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1answer
31 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 ...
0
votes
1answer
41 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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0answers
16 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 ...
1
vote
1answer
20 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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0answers
17 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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0answers
30 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 ...
0
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1answer
20 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 ...
0
votes
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.
1
vote
1answer
51 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 ...
2
votes
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
votes
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 ...
1
vote
1answer
83 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, ...
1
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2answers
33 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 ...
2
votes
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:...
0
votes
1answer
26 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','...
1
vote
1answer
42 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, ...
1
vote
1answer
34 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 ...
1
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1answer
32 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 ...
0
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1answer
89 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 ...
2
votes
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 ...
0
votes
1answer
52 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 ...
0
votes
1answer
54 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 ...
1
vote
1answer
38 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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vote
1answer
97 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 ...
0
votes
1answer
45 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/...
0
votes
1answer
39 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 ...
0
votes
1answer
68 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 ...
0
votes
1answer
54 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?
1
vote
4answers
70 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 ...
1
vote
1answer
68 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 ...
3
votes
1answer
85 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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0answers
81 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 ...
0
votes
1answer
240 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....
1
vote
2answers
189 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 (...
0
votes
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).
1
vote
1answer
397 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 ...
0
votes
0answers
120 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
votes
0answers
40 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 ...
