I want to extract Landsat TM/ETM based NDVI value for 1000-point location of China for 10 years (2004-2014) study period. As, these points are distributed in the entire china, downloading the Landsat images and computation of NDVI myself for that point location is much time consuming. Therefore, I am looking some geoportal (or some R scripts) from where I can extract Landsat TM/ETM based NDVI value or can use R script to automatic download images and compute the NDVI. I am looking for your suggestion.
I have used a python module to download and processing Landsat 8 images. I'm not sure if actually works for Landsat TM/ETM.
https://pythonhosted.org/landsat-util/overview.html
Cheers
Hello, I use the extract values to points from ArcGIS. It is the easier way to acquire the data by coordinates.
https://www.youtube.com/watch?v=wrMAEq1Ujco
On the other hand, you can consider use R with the next link https://gis.stackexchange.com/questions/279079/extracting-value-of-raster-with-coordinates-using-r
Cesar Ivan Alvarez my question is not how to extract NDVI value in given point location but how it can be done efficiently in the case of larger area. For example my point location are distributed in 168 landsat scene, covering almost entire China. Downloading them individually and NDVI computation manually may take much time. Therefore, I am looking some efficient and automatic way to solve this problem.
Lizardo Reyna Thanks, it would be useful when using Landsat 8 OLI
Not sure if this is the best method, but Google Earth Engine is one of the options. Give it a try.
- https://earthengine.google.com/
- https://www.youtube.com/watch?v=Wik07UyjnDs
- http://www.acgeospatial.co.uk/time-series-on-landsat-data-gee/
Dear Bipin Kumar Kumar Acharya You can order NDVI images on demand for all the required Landsat TM/ETM+ scenes using the website https://espa.cr.usgs.gov/ and then extract the values for your required lat/long using IDL or ArcGIS as suggested by Cesar Ivan Alvarez
uhammad Bilal [Ph.DThank you much for your suggestions. I think the best solution for this problem is to order NDVI using the website https://espa.cr.usgs.gov/ .Thank you so much once again.
Dear, I use the extract values to points from QGIS-SAGA. It is the easier way to acquire the data by coordinates.
https://www.youtube.com/watch?v=Mx_M3fB3f6Q
The best option to me is to compute the entire NDVI, import yr points and extract the values to the points.... You can then export it to excel or perform some geostatistical assessment of them. All these are so cool in ARCGIS. cheers.
Extract value to points in ArcGIS is a good option. Even the NDVI images may be stacked for extraction of spatial and temporal values
I do not know how much automation is done by some portal as far as Landsat NDVI generation and extraction is concerned. But you can try https://vedas.sac.gov.in/vstatic/vegetation_monitoring/index.html portal for MODIS based NDVI time series analysis for such work.
You can use Google Earth Engine
https://developers.google.com/earth-engine/tutorial_api_06
This video may help.
https://www.youtube.com/watch?v=Q14iCHnfozw
There are also a few new packages that deal with NDVI and remote sensing in R
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