Export values from Sentinel 2

[giannis]

I have an image corrected with sen2cor from Sentinel 2 and i am trying to extract the pixel value. However when i do that i don t have any result files. Why is that?

[ABraun]

Please describe how you extracted the pixel value. What is your overall aim? Maybe there is another way to achieve it.

[giannis]

Just by using the export->expart pixel values. Another solution that i was thinking is to resample the atmospherically corrected data to 60m (since all of them have already a resolution of 60m from sen2cor).
What do you think?
Any other ideas?

[ABraun]

Sorry for asking again - do you need the spectral values of a single pixel or a larger region? Necessarily as a text file?

[giannis]

Imagine i have several images and i want the pixel values at specific lon,lat and from specific bands . I don t care if there are in a text file or not.

[ABraun]

you should test the time-series tool then.

Time Series (Temporal) of NDVI

I cannot understand this. I tried it myself with the following steps and it works: @PiriReis: If you follow these steps, it works. Open 5 S2 images in SNAP [grafik] Test the time-series tool for band 3 [grafik] it works [grafik] Calculate index (I used the VI [NIR/Red] for the sake of simplicity) for each band [grafik] band in stack [grafik] Right-click on new band and click ‘convert band’ so it becomes permanent [grafik] Save all products (this takes time because t…

Besides that, the EO Browser delivers a very easy method for that:

Multi-year time series of multi-spectral data viewed and analyzed in Sentinel...

[giannis]

But imagine that i have them at very different locations and time periods around the Mediterenean Sea so i cannot choose a specific polygon or location. I copy an image of my points

[ABraun]

This helps me understand.
Have you considered the pin manager to place pins at these locations and extract the values from there?

Have a look at marpets explanations here: How to extract value from sentinel 3 OLCI maps for a specific point.?

[giannis]

This is the tool that i was originally using describbed How to extract value from sentinel 3 OLCI maps for a specific point.?.

But it doesn t give any output if you give sentinel 2 corrected images with sen2cor.

[ABraun]

I still don’t see the problem.

[giannis]

But in order to have this output you have resampled and subsetted the original image?

[obarrilero]

Currently, the extract pixel operator does not support the multi-size products, so you have to resample the S2, but in the next version of SNAP, this support will be added.

[mohsine1818]

i need this information to make burned area

[ABraun]

the screenshot you show is used to create a subset from a raster based on coordinates and line/row numbers. It can be accessed through the graph builder only (the one from the GUI tools looks different). I’m not sure how this relates to burnt area mapping, but you find it here:

1. Open the Graph Builder

2. Search for “Subset” like this
   

   

3. Connect the graph and make your settings:
   

   

[mohsine1818]

S2A_MSIL2A_20190909T110621_N0213_R137_T30STE_20190909T142623S2A_MSIL2A_20190820T110621_N0213_R137_T30STE_20190820T142040
i use this image
how can i extract value of x and y and width and height to put it in subset

[ABraun]

You define x, y, width and height according to the area of interest. No values to extract with this tool, besides the raster subset itself.