Questions tagged [ndvi]
Normalized Difference Vegetation Index is used to quickly identify vegetation and its condition in remotely-sensed data.
796 questions
1
vote
0
answers
48
views
How to find the precise scale parameter value accurately to precise decimal places in Google Earth Engine
I am training a classifier and results change drastically upon ±.00001 level of zoom precision to get the final trained output.
Is there a way to find out accurate zoom level in which training ...
0
votes
1
answer
50
views
NDVI for Landsat gives results for the entire world
I am trying to get NDVI from Landsat-8 for a region starting from 2013 uptil Sep 2024 in Google Earth Engine. I am attempting time series and am looking for results for every month for all these years ...
0
votes
0
answers
12
views
Landsat 8 C2 L2 FOR NDVI
When I download Landsat 8 C2 L2 image from USGS and apply directly NDVI formula the value is ok it is in range -1,+1 while where I am applying scale factor which is (0.0000275)-(0.2) for each band ...
0
votes
1
answer
98
views
The code for calculating vegetation indices in GEE
I want to write a code to calculate the vegetation indices in GEE so that there are no clouds on the field polygon
But this filter, filters the entire image collection, not just the polygon!
Map....
- 1
1
vote
1
answer
36
views
Calculate VIs in GEE over an image
In my study area shown in red line, I calculated an image of canopy height in GEE. I want to calculate NDVI, EVI, and other vegetation indices over this image. I know how to calculate the VIs in GEE ...
- 645
1
vote
1
answer
40
views
NDVI percentage
I took pictures with my drone for Corn field and I get the Orthomosaics and calculated NDVI at each interval, and make color for each interval as you can see in Image.
Now I want to calculate the ...
3
votes
1
answer
98
views
Symbology display issues in raster layers
The code below aims to apply symbology based on NDVI values to the selected raster layer. However, after running the script it does not display correct information (image 1). I need to access layer ...
- 797
0
votes
1
answer
23
views
No features in Sentinel 2 Level 2A Harmonized dataset
I am running into a problem I am trying to calculate MCARI and NDVI from the Sentinel 2 Level 2A dataset and it doesn't have any feature for the data range from 2017 to Dec 2018. Can anyone advise me ...
1
vote
1
answer
44
views
Inverted NDVI output using ArcGIS Pro [closed]
I am trying to perform an NDVI on multiple rasters in a folder. As I understand it, an NDVI output has a range of values from -1 to 1. Values 0 and above should represent vegetation and values below ...
- 41
0
votes
0
answers
17
views
EVI2 calculation，Issues arising from collection 1 to collection 2
Old code:
var L5_EVI2= function(image) {
var evi2 = image.expression( '2.5 * ((NIR - RED) / (NIR + 2.4 * RED + 1))',
{
'NIR': image.select('B4'), 'RED': image.select('B3')
}
).rename('EVI2');
var ...
- 1
0
votes
0
answers
38
views
Landsat 7 NDVI errors?
I calculated NDVI using a method from a previous question I asked. I forgot that Landsat 7 has errors following 2003. I don't mind running it again but is there ways to correct for this error?
# Start ...
0
votes
0
answers
17
views
Sample NDVI time series for points and retaining the unique point ID in Google Earth Engine
In Google Earth Engine, I have a feature collection of points with one column that is the "Feature Index". Now I am extracting time series for every point. How can I retain the "Feature ...
- 3
0
votes
1
answer
117
views
What's the difference between collection2 of Raw Scenes and TOA
I'm a beginner of GEE, I can't distinguish the difference of Landsat collection2 of Raw Scenes and TOA, such as 'USGS Landsat 7 Collection 2 Tier 1 Raw Scenes' and 'USGS Landsat 7 Collection 2 Tier 1 ...
0
votes
1
answer
109
views
Can't calculate NDVI from Landsat 8 data
I have acquired Landsat 8 data from earthexplorer; I got band 5 and 4 only as they are the necessary bands to calculate the NDVI. I've followed every YouTube video and article online with no chance of ...
- 1
0
votes
1
answer
27
views
Error trying to calculate the NDVI of about 20 cities in the USA in GEE
I am new to GEE. I am trying to calculate the NDVI of about 20 cities in the USA. However, I keep getting this error:
Error: User memory limit exceeded. (Error code: 3)
I don't know how to solve it. ...
- 1
0
votes
1
answer
75
views
Calculating NDVI using OrfeoToolbox
Platform: Windows 11
Aim trying to achieve: I have downloaded some multispectral test data from OpenDroneMap (ODM) forum. The data is captured with DJI Mavic 3M. What I want is to analyze NDVI, NDRE, ...
- 11
-1
votes
1
answer
33
views
Error generating chart: Image.parseExpression: Expression contains undeclared variables: [max] for vci, and tci [closed]
I have a problem creating the chart and there is error message expression undeclared variables
var geometry =
/* color: #d63000 */
/* displayProperties: [
{
"type": &...
0
votes
0
answers
35
views
How to the image date/ metadata used when using the .median filter in GEE?
I am processing LST, NDVI, NDBI, & UHI data in a 1 year period. I used the .median filter function for filtering the dates.
My question is, how do I know what images to use? I've tried the ...
-1
votes
1
answer
42
views
Does MODIS dataset (MOD09GQ) require atmospheric correction to calculate NDVI?
It took a dataset of satellite images with a high frequency of reception (1 day) to work. The work consists in studying the change in the NDVI coefficient at a certain site during the year.
I took ...
- 65
-1
votes
1
answer
29
views
Cannot export NDVI map to google drive on Google Earth Engine
I am trying to export an image of NDVI before a wildfire to my Google Drive but it keeps failing and I am unsure of what the issue is.
the variable burntsite is a polygon I drew.
var prefire = ee....
- 1
0
votes
0
answers
97
views
TypeError: Image data of dtype object cannot be converted to float
The main functionality of the script is to extract GeoJSON data, load it into Earth Engine, retrieve Sentinel-2 imagery, calculate the mean NDVI, and visualize the NDVI for each GeoJSON feature.
My ...
- 131
0
votes
0
answers
28
views
Cloud Masking and Compositing Landsat SR Timeseries in GEE Python Colab - Fails to Export
I'm trying to create a seasonal (dry/wet) Landsat NDVI time series for multiple sites in an area over a span of approximately 30 years within Google Earth Engine's Python Colab. Each site will have a ...
- 1
0
votes
1
answer
83
views
Landsat NDVI Anomaly Google Earth Engine
I am interested in calculating Monthly NDVI anomaly using Landsat. My objective will calculate long term monthly NDVI with all Landsat collection 2 sensors. In this simpler example I am only using ...
- 35
0
votes
1
answer
93
views
Mann-Kendall trend test on GEE returns empty band
I am using GEE to run the Mann-Kendall trend test on NDVI over my study area from 2001 to 2023. I want to show the NDVI trend for each individual month for the 22 years, which means January 2001,2002.....
0
votes
0
answers
33
views
How to analyze NDVI time series data
I am analyzing time series data of NDVI within an AOI.
Ultimately, I would like to plot the average monthly data in a box-and-whisker diagram.
Here is the problem.
The number of months with ...
- 23
0
votes
0
answers
37
views
Convert irregular time series to regular for running bfast model
I have NDVI rasters extracted from Sentinel-2 with irregular time series over a year and missing data of July. I would like to generate the irregular time series to a monthly regular time series in R ...
- 379
0
votes
1
answer
27
views
Extract, plot and export as a table a vegetation index time series from multipoint feature collection in Earth Engine
Reference is to a tread I posed years ago and was solved Extract pixel values from several bands of an image and export in a single table in Google Earth Engine
The challenge now is to create S2 NDVI ...
- 531
0
votes
0
answers
50
views
Issues with Clipping Shape of Sentinel-2 NDVI Image in Google Earth Engine Python API
I'm working on an agricultural analytics application where I need to generate NDVI images from Sentinel-2 data for user-defined polygon areas. The backend is implemented in Python using Flask and the ...
0
votes
1
answer
91
views
Maps and graphs not rendered for NDVI-based variable using Google Earth Engine JavaScript API
I’ve written the code below (sorry if this is a lengthy block) to calculate ESPI which is annual mean minus monthly average standard deviation of NDVI. Though the code ran without any problem, maps ...
- 202
0
votes
1
answer
96
views
Get the slope of a linear regression in Google Earth Engine
I have an image with 3 bands that represent the NDVI value from 3 different years:
// Load Landsat imagery for different years
var landsat2019 = ee.ImageCollection('LANDSAT/LC08/C01/T1_TOA')
....
- 193
1
vote
1
answer
57
views
Direct use of Sentinel 2 L2A imagery for vegetation analysis
I am working on my research to calculate the green vegetation in the study area using sentinel 2 L2A 10m resolution. Do I need to perform any correction or smoothing before analysis?
- 13
0
votes
1
answer
104
views
Eliminating missing pixels in NDVI time series analysis by temporal gap filling with linear interpolation to get a smooth result
The code is running correctly but it doesn't give me a smoothened result. Anyone who can help me out?
var startDate = '2015-01-01';
var endDate = '2023-12-31';
var images = sentinel.filter(ee.Filter....
- 1
0
votes
1
answer
36
views
Trying to create mask to eliminate false NDVI numbers in GEE time series analysis using Sentinel data
It keeps given me the error that ndvi.gte is not a function, I shared my code below:
var images = sentinel.filter(ee.Filter.date(startDate,endDate)).filterBounds(geometry)
print(images);
var ndvi = ...
- 1
0
votes
0
answers
37
views
Large values while calculating on normalized difference indexes
I've encountered a problem while calculating NDDI index (NDVI-NDWI/NDVI+NDWI) in ArcGIS Pro for my bachelor's thesis. I'm working with Raster Calculator (the problem appeared in both Image Analyst ...
- 1
0
votes
1
answer
121
views
Unable to compute graph in Google Earth Engine when trying to compute mODIS NDVI Time series analysis of a small region in Crete, Greece
I want to make a simple time series analysis of the past 8 years using MODIS data but I'm unable to compute the graph as I get the following message:
Error generating chart: Collection.first: ...
- 1
0
votes
0
answers
46
views
Extracting seasonal maximum from smoothed MODIS NDVI time series in Google Earth Engine
I am trying to extract the seasonal maximum NDVI value (01st June to 31st October) from 2000 to 2023, i.e., total 24 NDVI images. For that I have imported the MOD13A2 datasets in the Google Earth ...
- 21
0
votes
0
answers
34
views
Erdas - Export LUT Instead Of Real Values
I am using Erdas 2022.
I have NDVI index of an imaging, and after creating it, the view shows a LUT which is not the original pixels, which is essentially the automatic stretching of the program.
I ...
- 101
1
vote
1
answer
122
views
Skewed NDVI values
I'm analyzing open-source NIR images with Python. I'm a novice to remote-sensing and have a doubt about my NDVI results.
I calculate my NDVI like so:
with rasterio.open(self.tif_path) as src:
...
- 13
0
votes
0
answers
35
views
NDVI temporal analysis error in Sentinel
I need to do a temporal analysis of NDVI with Sentinel images from 2019 to 2023, using monthly composites and extract the NDVI value for random points created. However, it is generating empty data.
...
0
votes
0
answers
30
views
Projecting Landsat image correctly using Build Virtual Raster
I am trying to make one complete image using B4 images from USGS and another using B3 images to then calculate NDVI. The issue I'm having is a single image not lining up in the same projection (see ...
- 11
1
vote
1
answer
116
views
Google Earth Engine Landsat NDVI
I'm trying to map deforestation using Landsat NDVI time-series. But unfortunately I can't find the data from 2022 - 2023, on the other side data before that year is available. Can someone explain me ...
- 31
0
votes
0
answers
32
views
Google Earth Engine NDVI no value
I'm using GEE for NDVI (using landsat 8) but there is many holes in my image, can someone explain me what happened? here's the code
// Function to mask clouds using the quality band of Landsat 8.
var ...
- 31
0
votes
0
answers
111
views
NAN String on Maxent
I'm using NDVI for one of my environmental layers, i got it from google earth engine and process the data using ArcGis Desktop. I already convert it to ascii and check there's some NAN in my data. ...
- 31
0
votes
0
answers
54
views
NDVI calculation problem in QGIS
I have a satellite image with 4 bands, R,G,B,NIR.
I have used the QGIS raster calculator to produce an NDVI - standard (NIR-R)/(NIR+R). I am expecting an output between 1 and 0, but the raster has the ...
0
votes
1
answer
285
views
Get monthly NDVI and NDWI median for a year, from Landsat collection Google Earth Engine (GEE)
I am trying to get NDVI and NDWI per month, based on the median of the images in one month. For this, I am using Landsat8 collection an year 2018. I keep getting empty bands for the var monthlyStats. ...
0
votes
0
answers
36
views
Using same spatial resolution for NDVI and LST data in machine learning model
I am currently developing a drought forecasting machine learning model and this is my first time handling satellite data. Two of my data sources are the MOD13A1 dataset from Google Earth Engine for ...
0
votes
1
answer
39
views
Why wont GEE upload my image to drive?
Im trying to export to my drive a cropped image of NDVI from the dataset 'LANDSAT/LC08/C01/T1_8DAY_NDVI', in the layer it shows perfectly but when i submit the task to upload it to drive it never ...
- 1
0
votes
2
answers
395
views
Convert Landsat 9 Surface Reflectance product DN to surface reflectance values
I downloaded the Landsat 9 L2 imagery from Earth Explorer for the purpose of calculating NDVI. However, when opened in ArcMap 10, the pixel values are in the range of 7000 to 45000. I understand that ...
1
vote
0
answers
137
views
Creating interactive chart in Jupyter Notebook using Geemap
This code applied the custom date to the x-axis. But I do not want this. I want to show the date on which the Image is taken by using "system:index" property of the Image. Also, This code ...
- 131
1
vote
1
answer
172
views
Creating NDVI and Cloud Chart in Jupyter Notebook
I am trying to calculate NDVI and cloud pixel percentage. I have successfully done this but I am facing a problem in creating a chart of it in Jupyter Notebook, as I am new to Python so I tried ...
- 131