Obtain FVC model from sentinel 2A images

Hi everyone,

I write you for my research, obtain a FSMH model. To obtain this model I start from sentinel 2A products, who have already undergone atmospheric correction, and I need to obtain a FVC model. Now, when I do it (Optical --> Thematic Land Processing --> Biophisical processor and select FVC) SNAP gives me the following error:

I tried resampling through the operator S2 Resampling processor (in Optical --> geometric --> S2 Resampling processor) but I have a question for you, what is the correct processing parameters to obtain a resampling at 10m, considering that some spectral bands are already at 10m or 20m and others at 60m?

resampling s2

Thank you.

yes, the S2 Resampling is the correct way. You can, however, also disable the “save as” option in this step. This creates a logical product which you can use as input or the next tool.

grafik

Thank you for reason ABraun, but I have not understood if the processing parameters must remain the basic ones or the options need to be changed to get a more accurate result.

For example what is the difference in Upsampling method between bilinear, nearest and bicubic? And in downsampling method? In Flag downsapling?

I’ve tried with this parametres, are correct?

Cattura2

and this is the final result of FVC, what is the green pixel?

On thei differences of resampling, please have a look here: Radar Mosaic

There is no good or bad technique, this depends on what you want to do with the result. You can calculate nearest and bilinear and compare the results.

Upsampling means bringing pixels of lower resolutions to a higher spatial resolution, e.g. 60m and 20m to 10m. Downlsampling is the opposite. So again, it depends on your output product and resolution which of both is relevant.

thank you ABraun, now I have another question for you. If I have two close S2 images (acquire in the same day) and I want to get a single image that is a mix of two, but in the conjunction area the two images are superimposed, I have to use Raster --> Mosaic?

In this case what kind of Variable e Condition I must choose?

there is a way in SNAP with which I can choose how to process the overlapping pixels of the two images, for example if I wanted the overlapping pixels to take an average value between the two images (like in other GIS software).

thank you

have you seen this tutorial?

Thank you ABraun, I’ve try to apply the operator used in tutorial. But i’ve encountered problems, when I used the multi-size mosaic with the S2A image and I processed them without saving them the result is correct but when I tried to save them on hardisk the result is a black image. I’ve tried many times with this operator and mosaicing operator (with the same images but resampled) but the best results that I’ve obtain is a image with a huge pixels. You have ideas about the problem?

the crucial point in the video comes at 2:20 when the resolution is changed from 1000 meters to the native resolution of the input product, please check.