Getting metadata (tile ID) - blank image

Apps / Services Python SDK
1

Hello ,

I’m trying retreieve sentinel-2 images together with their tile ID. I have used this post in order to create me new request, but for some reason I get blank images (same issue as the person who posted that post exeprienced).

This is my evalscript+ request:

evalscript = """
function setup() {
  return {
    input: [
      {
        bands: ["B02","B03","B04","B8A","B11","B12"]
      }
    ],
    output: [{
      bands: 8,
      sampleType:"FLOAT32"
    }],
    mosaicking: Mosaicking.TILE
  }
}

function updateOutputMetadata(scenes, inputMetadata, outputMetadata) {
    outputMetadata.userData = { "original_tile_id":  scenes[0].tileOriginalId }
}

function evaluatePixel(samples) {

  const ndvi = index(samples.B08A, samples.B04)

  return [ndvi,samples.B02,samples.B03,samples.B04,samples.B8A,samples.B11,samples.B12]
}
"""

#retrieving dates.... that works (checked and got list of dates)

# request per date

    for d in sen2_dates:
        
        request = SentinelHubRequest(
            evalscript=evalscript,
            geometry=geom,
            input_data=[
                SentinelHubRequest.input_data(
                    data_collection=DataCollection.SENTINEL2_L2A,
                    time_interval=(d, d),
                    mosaicking_order='leastCC'
                )
            ],
            responses=[
                SentinelHubRequest.output_response('default', MimeType.TIFF),
                SentinelHubRequest.output_response('userdata', MimeType.JSON)
            ],
            bbox=bbox,
            size=bbox_size,
            config=config
        )
        
        data_request = request.get_data()[0]
        img=data_request['default.tif']
        platform=data_request['userdata.json']['original_tile_id'].split('_')[0]
        
        ndvi_sen2=img[:,:,0]
        

        rgb=np.dstack((img[:,:,3]*2.5,img[:,:,2]*2.5,img[:,:,1]*2.5))
        plt.figure(figsize=(8,3))
        plt.matshow(rgb)
        plt.title('RGB sen-2')
        plt.show()

The result s blank images.
My end goal is to get both tile id and image, not blank.
Thanks :slight_smile:

2

Hi @reutkeller ,

Since you’re using Mosaicking: TILE, multiple scenes will be returned.

I see you select the first scene by specifying "original_tile_id": scenes[0].tileOriginalId in the updateOutputMetadata function. To obtain the image of the first scene, you need to select the first image in samples as well. E.g., const ndvi = index(samples[0].B08A, samples[0].B04).

Best Regards

1 Like
3

@chung.horng thank you! this worked for the bands, but, very weird, it returns blank image only for the NDVI.

function evaluatePixel(samples) {

  const ndvi = index(samples[0].B08A, samples[0].B04)

  return [ndvi,samples[0].B02,samples[0].B03,samples[0].B04,samples[0].B8A,samples[0].B11,samples[0].B12]
}
"""

This is confusing :sweat_smile:

4

Hi @reutkeller ,

It is because the input band is defined as “B8A” instead of “B08A”. Should work with const ndvi = index(samples[0].B8A, samples[0].B04).

Best Regards

1 Like
5

oh right.

Thank you!