Cloud Mask - S3

Optical Toolbox
#1

I am trying to calculate the area covered by cloud within Sentinel 3 imagery.
I have downloaded both L1 and L2 imagery from Scihub and as such have the quality_flags_bright mask for the level 1 imagery and the LQSF_CLOUD and LQSF_CLOUD_AMBIGUOUS Masks for the level 2 imagery.
Is there a way of calculating the area for each mask within SNAP? Alternatively is there a way to easily export the products into ENVI to do some raster analysis upon the product.

Regards Harry.

#2

You can easily export to envi by selecting from the menu File/Export/ENVI.

The area of a mask can be calculated by Raster/Masks/Mask Area
With the Mask Manager (View/Tool Windows/Mask Manager) you can combine both LQSF masks to a single cloud mask.

What can’t you do with SNAP, that you want to use Envi? Wher can we improve?

#3

Is it possible to define a mask on an image (I’m working on SEVIRI images), for example a geometry mask with polygon, and then export it as an ENVI boolean image of the same dimension and geolocation as the initial SEVIRI image? In File/Export/ENVI the ENVI export is disabled. (Very new to SNAP and forum, but I haven’t found any hint yet…)

#4

This is possible. Following the steps to be done:

  1. Draw the polygon on the image
  2. Create a new band by using Band Maths. In the expression use the name of the geometry created. Ensure that you don’t create a virtual band (uncheck the corresponding checkbox).
  3. Save the product to BEAM-DIMAP format and find the Envi .img/.hdr file in the *.data directory or remove all other bands from the product and then export to Envi format.