Help with time ranges in API

1

When we given start and end time dates for quering date in sentinal-hub api, have read that “If two time points (start and end of the time range) are specified, the service will return a mosaic of the images from that time range”

Mosaic is mostly done to fuse mostly non-overlapping regions into a single image, but here our region will be present in many images and have a time-series values but only 1 image is returned. It will take on so many different values in this time period as well. Don’t understand how values for overlapping region among the many images are estimated. Are they averaged? How to interpret this statement?

Also is there a way to get the capture date of the image returned? Currently get_data() returns only a list with the image array.

The request made is from the examples:


request_true_color = SentinelHubRequest(
    evalscript=evalscript_true_color,
    input_data=[
        SentinelHubRequest.input_data(
            data_collection=DataCollection.SENTINEL2_L1C,
            time_interval=('2020-06-12', '2020-06-13'),
        )
    ],
    responses=[
        SentinelHubRequest.output_response('default', MimeType.PNG)
    ],
    bbox=betsiboka_bbox,
    size=betsiboka_size,
    config=config
)
2

The reason that only one image is being returned is because the default SIMPLE mosaicking parameter in the Evalscript is designed to do so. If you don’t set a mosaicking parameter the system will default to SIMPLE. You can ready more about the 3 types of mosaicking in our documentation page.

What your flattened image returns is defined in your payload. Here you haven’t specified anything in your request_true_color, so the default mosaickingOrder value will be used. You can set the mosaickingOrder in your python code by adding the parameter to your input_data (see this example). By default the value is set to mostRecent, but you can also use “leastRecent” or “leastCC”.

If you haven’t see it yet, the Sentinel Hub Process API webinar is a great source of information to understand options and features of requests.

Why so many default parameters? The use of default values is designed to remove complexity from requesting satellite images, but provides the flexibility needed when you need specific features.