Hello,
I want to study the evolution of the NDVI measure on agricultural soil over one summer in the northern hemisphere. Ideally, I would need a geo-referenced RGB&IR image of the same region every week during the whole summer. If this is not possible with IR information, I could manage to work with just RGB images and study the Visible Atmospherically Resistant Index (VARI) which approximates the NDVI without requiring IR information. The next best thing would be less frequent images (i.e. one every 2-3 weeks).
As I have experience in image processing but not specifically in remote sensing or UAV/satellite survey, I don't know where to look for such data or even if it exists somewhere. Can anybody point me in the right direction? Papers on this subject would also be appreciated.
Regards,
Bruno Martin
P.S.: Some links related to what I want to do.
https://blog.dronedeploy.com/identifying-crop-variability-whats-the-difference-between-ndvi-false-ndvi-and-vari-plant-health-98c380381a33
http://www.mdpi.com/2072-4292/2/3/673
Article Calibration Methodology for Mapping Within-field Crop Variab...
There are a lot of satellite and product, you should give more information such as spatial resolution , coverage area and time range.
Dear Bruno:
LANDSAT 8 OLI has temporal resolution of 16 days, and spatial resolution of 30 m.Sentinel 2 has 5-day temporal resolution, and spatial resolution of 10 m.
both have RGB and NIR bands, and can be downloaded with atmospheric correction (via registration and request, it takes a few days) here: https: //earthexplorer.usgs.gov/.
If you do not want the atmospheric correction, there is no need to request it.
Hugs, Luís
I agree with Mr.Luis, Landsat 8 and Sentinal 2 are good choise for NDVI study at a 30 meter resolution and high temporal resolution
If you want a time-series NDVI data than you can go for AVHRR based NDVI data which provides weekly data since 1983. But it gives data in coarse resolution.
Here is a little more information about my problem.
The goal would be to provide a monitoring service to big farms and use either available satellite images (like the Sentinel 2 that people suggested) or UAV images acquired periodically to help plan irrigation and other specific measure adapted to sub-regions of the complete field.
That monitoring would be based on analyzing the variation of NDVI data in time. For this, a relatively high temporal resolution is required (1-2 weeks at most).
As for spatial resolution, I guess 10m resolution could be sufficient and that's one thing I would validate in my study.
Thanks everyone for your very interesting tips and if these precisions bring you any new ideas, don't be shy!
Hi Bruno!
For irrigation, I recommend that you also check the possibility of using the NDWI:
Article NDWI?A Normalized Difference Water Index for Remote Sensing ...
This index is more sensitive to leaf water content than NDVI!
Hugs!
The NDVI is more useful for estimating vegetation cover or photosynthesizing biomass...
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