I would like to use sentinel 2A imagery to look at canopy cover in Northern Vietnam. The only problem is that ALL the recent images have large amounts of cloud in the area I want to look at.

Is it possible to use the cloud mask vector image that you can also download remove the clouds so that you can "see through" to the forest below?

And in this way use the imagery under the clouds to perform an analysis of canopy cover?

Otherwise are there any other options?

I need a decent resolution because the site is only 5000ha, so in this case I think all Landsat imagery is probably not fine enough.

  • the Sen2Three processor is one tool you can use.
    – moh
    Commented Mar 5, 2017 at 5:08
  • 1
    ...and how does Sen2Three magically see through clouds?
    – til_b
    Commented May 12, 2017 at 12:21

3 Answers 3


In optical remote sensing in the visible spectrum you cannot see through clouds. So there is nothing you can do, except to wait for images without clouds.

Cloud masks are (as far as i know) used to exclude clouded areas from (for example) landcover classification, because results there would be incorrect anyways.


As Aaron mentioned, you can sometimes use a cloud mask to insert cloud-free imagery into a cloudy image, but that only works if you a) do have cloud free imagery and b) you don't care that the resulting image is now a mosaic of images from different acquisition dates, and thus you cannot compute change detection etc. on it.

  • 1
    In some cases you can use a cloud mask to "insert" cloud-free imagery.
    – Aaron
    Commented May 17, 2016 at 12:32

The only alternative when no cloud-free images are available, is radar. You could try find some Sentinel-1 scenes, that are freely available.


Data sources by Sentinel can be obtained for free from the Copernicus Open Access Hub (https://scihub.copernicus.eu/). Data can be corrected for atmospheric conditions using semi-open source tools, such as SEN2COR. With the availability of open data that are now cloud free, we can expect far better data quality available to many more scientists in the coming years, where such data are crucial in monitoring the rapidly changing planet. Cloudless Sentinel-2 layer are also available on https://s2maps.eu

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