What steps are required in generating an NDVI from data products from different Landsat sensors?

[Georgeina]

I have data from Landsat TM 4-5, Landsat 7 ETM + and Landsat 8 OLI/TIRS.

 

how can I generate NDVI from these time series data sets

What critcial consideratiosn do I need to take or note when carrying out atmospheric corrections and radiometric corrections?

What are the important meta data information across all sensor data products when carrying out atrmospheric and geomertic corrections?

 

Your ideas and professional inputs will be greatly appreciated

 

Thanks

[am2]

at first radiometric calibration using DN->radiance

then atmospheric calibration using ATCOR,MODTRAN, FLAASH OR quick (some of them are methods some are tools)

at the end calculate ndvi,your metadata is used in atmospheric and radiometric calibration .

[Georgeina]

3 hours ago, am2 said:

at first radiometric calibration using DN->radiance

then atmospheric calibration using ATCOR,MODTRAN, FLAASH OR quick (some of them are methods some are tools)

at the end calculate ndvi,your metadata is used in atmospheric and radiometric calibration .

Ok dear am 2

 

Many thanks

 

Any videos to follow the tutorial as a beginner?

 

Warm regards

[mamadouba]

Georgeina, what software do you have access to?  Do you have access to a USGS EarthExplorer account?  You can order your products in bulk using the USGS ESPA interface (https://espa.cr.usgs.gov/login).  You can place an order up to 5000 scenes for L4/5, L7, and L8.  The available products include surface reflectance and several different indices (e.g., NDVI, EVI, SAVI, etc.), including a cloud/shadow mask for masking NULL values.  https://landsat.usgs.gov/sites/default/files/documents/espa_odi_userguide.pdf 

[am2]

On 4/20/2017 at 7:22 PM, Georgeina said:

Ok dear am 2

 

Many thanks

 

Any videos to follow the tutorial as a beginner?

 

Warm regards

Hi,

look at these videos which are for landsat 8

https://www.youtube.com/user/SuperLaser1979/videos

[Georgeina]

On 22/04/2017 at 2:46 PM, mamadouba said:

Georgeina, what software do you have access to?  Do you have access to a USGS EarthExplorer account?  You can order your products in bulk using the USGS ESPA interface (https://espa.cr.usgs.gov/login).  You can place an order up to 5000 scenes for L4/5, L7, and L8.  The available products include surface reflectance and several different indices (e.g., NDVI, EVI, SAVI, etc.), including a cloud/shadow mask for masking NULL values.  https://landsat.usgs.gov/sites/default/files/documents/espa_odi_userguide.pdf 

Dear Mamadouba,

 

Many thanks for your useful feeedback. Like I said earlier , I am cutting my teeth in Remote sensing and image processing.

 

So when you say the following products contains surface reflectance, i am a bit confused her e.

 

I am working with these products and thought that the bands pixels are submitted with DN values which I now need to convert to TOA reflectance.

 

 

And someone some where has already provided clues to the algorithm that can be used to convert DNs to TOA.

 

Please could you clarify exactly what you mean?

Again with the gap filling, I used the steps outlined by usgs on Landsat page

 

see link:  https://landsat.usgs.gov/gap-filling-landsat-7-slc-single-scenes-using-erdas-imagine-TM

which has also been confirmed by this video link: 

 

Are these methods significantly different from the one you are referring to ? that is usung the gap mask files

With kind regards

 

[mamadouba]

Hi Georgeina,

The data products that I was referring to in my post are only related to Landsat ordered through the ESPA interface.  ESPA provides the raw digital number (DN) along with a variety of higher level scientific products such as surface reflectance (SR), spectral indices (e.g., NDVI), Fmask (cloud and shadow), etc.  The spectral reflectance product has undergone radiance conversion and atmospheric correction using a physical based first principles radiative transfer model, namely 6S.  LEDAPS is applied to Landsat 4,5, and 7 and a similar algorithm (SR8) is applied to Landsat 8.  The purpose of ESPA is bypass all of the manual digital image processing that an analyst would otherwise have to undertake themselves (geometric, radiometric, atmospheric correction) so you can focus on the analysis.  In other words, ESPA provides research ready products.  

With regard to your work, are you just conducting an analysis, or do you want to learn these techniques yourself?  It is good to know the fundamentals behind image pre-processing and the best way to learn is to conduct the work yourself.  Is Erdas your primary image processing software or do you use ENVI, or other?