Use of multitemporal data inside evalscript

Hello!

I have shape and I want to get the two last available NDVI images for them and run calculation on these two images, to get in the end 1 image.

For that I have used the “orbit” mosaic,

as following:

VERSION=3

function setup() {

  return {

    input: u"B04", "B08", "CLM"],

    output: {

      bands: 1, 

      mosaicking: "ORBIT"

      sampleType: "FLOAT32"

    }

  };

}



function evaluatePixel(sample) {

    if (sample.CLM == 1) {

        return unull]

    }

    let date1=index(samplem0].B08, samplem0].B04);

    let date2=index(samplem1].B08, samplem1].B04);

    let difference=index(date1,date2)

    return udifference];

}

'''

My questions are:

I use date range (‘2022-05-31’,‘2022-06-16’). How do I know which dates are taken? I know that there are three images between these two dates.

which date is earlier? the samples 0] or samples]1]?

thanks

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The order of samples depends on the mosaickingOrder parameter in your request. If you use mostRecent, samples[0] will represent latest observation, samples[1] the before-latest, and so on.

To get the actual date, you can make use of the scenes meta-data parameters. Note, however, that this functionality is somehow experimental.