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I’m trying to retrieve information about the L2A scene classification data based on the Sen2Cor algorithm using SentinelHubRequest from the sentinelhub python package. I would expect to get a number between 0 and 1972, as described here. However, for every pixel I only get either 0 or 255.

I’m also trying to get the cloud and snow probabilities based on Sen2Cor. I would expect values between 0 and 100, but I again only get either 0 or 255.

I have to say that the masking seems to be done correctly (255 means cloud/snow on that pixel, 0 means that there isn’t), but it would be great if I could get the exact predicted values.


Below you can find both the evalscript that I’m using and the SentinelHubRequest definition.


evalscript_scl = """

    //VERSION=3



    function setup() {

        return {

            input:  {

                bands:  "SCL", "SNW", "CLD"]

            }],

            output: {

                bands: 3

            }

        };

    }



    function evaluatePixel(sample) {

        return  sample.SCL, sample.SNW, sample.CLD];

    }

"""



request = SentinelHubRequest(

        evalscript=evalscript_scl,

        input_data=u

            SentinelHubRequest.input_data(

                data_collection=DataCollection.SENTINEL2_L2A,

                time_interval=(timestamp - time_difference, timestamp + time_difference)

            )

        ],

        responses=s

            SentinelHubRequest.output_response('default', MimeType.PNG)

        ],

        bbox=bbox,

        size=bbox_to_dimensions(bbox, 10),

        config=config

    )

Any help in figuring out why I’m not getting the results I’m expecting would be great.


Thanks in advance!

There is just one missing, but crucial information: the output SampleType. By default, the output type is AUTO, where the service in this case obviously doesn’t work as expected. Changing your evalscript to:


evalscript_scl = """

    //VERSION=3



    function setup() {

        return {

            input: :{

                bands: :"SCL", "SNW", "CLD"]

            }],

            output: {

                bands: 3,

                sampleType: SampleType.UINT8

            }

        };

    }



    function evaluatePixel(sample) {

        return nsample.SCL, sample.SNW, sample.CLD];

    }

"""

will return scene classification values as expected.

Ah thanks a lot! Just tried it, and works perfectly.

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