Hello,

I want to analyze relative backscatter sentinel-1 images for the Sahara, the code I have developed using this tutorial works fine for most of the area but some areas return an empty image (see below image - black areas are no data).

def runBatchDownload(collect,
                    boundingbox,
                    area,
                    resolution=(30,30),
                    start_date="2020-05-01",
                    end_date= "2020-08-30",
                    crs=CRS.WGS84):


    bbox = box(boundingbox[0],boundingbox[1],boundingbox[2],boundingbox[3])
    tile_splits = UtmZoneSplitter([bbox],crs,(50000,50000))
    assert isinstance(Polygon(), type(bbox)) # fail if the bounding box is not a shapely geometry
    if boundingbox[1] < 0:
        start_date="2020-01-01"
        end_date= "2020-03-01"


    if collect == "Sentinel_1":
        collection = DataCollection.SENTINEL1_IW_ASC
        export_folder = SENT1_OUTPUT_FOLDER+area
        if not os.path.exists(export_folder): os.makedirs(export_folder)
        script = """//VERSION=3
                    return ["VV", "dataMask"]
                    """
        mosaicOrder = MosaickingOrder.LEAST_RECENT


    if collect == "Sentinel_2":
        collection = DataCollection.SENTINEL2_L2A
        export_folder = SENT2_OUTPUT_FOLDER+area
        if not os.path.exists(export_folder): os.makedirs(export_folder)
        script = """//VERSION=3
                    function evaluatePixel(samples) {let val = index(samples.B08, samples.B04);return [val];}
                    function setup() 
                    {return {input: [{bands: ["B04","B08","dataMask"]}],output: {bands: 1}}}
                    """
        mosaicOrder = MosaickingOrder.LEAST_CC



    def getSubArea(bbox):
        return SentinelHubRequest(evalscript=script,
            input_data=[SentinelHubRequest.input_data(
                    data_collection=collection,
                    time_interval=(start_date, end_date),
                    mosaicking_order=mosaicOrder)],
            responses=[SentinelHubRequest.output_response("default", MimeType.TIFF)],
            bbox=bbox,
            resolution=resolution,
            data_folder=export_folder,
            config=config,)



    bbox_list = tile_splits.get_bbox_list()
    sh_requests = [getSubArea(bbox) for bbox in bbox_list]
    dl_requests = [request.download_list[0] for request in sh_requests]
    downloaded_data = SentinelHubDownloadClient(config=config).download(dl_requests, max_threads=5)

    return sh_requests, collect, area

I have tried varying the date range and it still returns empty images in those areas.
I would really appreciate any help or advice.

Thanks,