Notebook

Interactively browse STAC footprints¶

STAC items contain information about the spatio-temporal footprint of the data they catalog. Using Jupyter Widgets, in particular ipywidgets.interact and ipyleaflet, we can quickly build an interactive tool for visualizing item footprints. This can be helpful for understanding the path a satellite takes over earth or debugging strange looking item footprints.

We'll start by grabbing some Sentinel-2 L2A items from the Planetary Computer's STAC API.

In [1]:

import pystac_client

catalog = pystac_client.Client.open(
    "https://planetarycomputer.microsoft.com/api/stac/v1"
)

search = catalog.search(
    collections=["sentinel-2-l2a"],
    datetime="2023-04-01",
    query={"platform": {"eq": "Sentinel-2B"}},
    sortby="datetime",
    max_items=200,
)

items = search.item_collection()

Next, we'll build up our tool. We start with our placeholders:

An ipyleaflet.Map object
An empty ipyleaflet.GeoJSON layer, which we add to the map

Then we use ipywidgets.interact to browse the list of items. This gives us a dropdown with the list of items, which we can scroll through to select a single item for display. The body of the function updates the state of our map to set

The center of the map to the center of the selected item
The data for the GeoJSON layer, to display the selected item's footprint

In [ ]:

import ipywidgets
import ipyleaflet
import shapely.geometry

m = ipyleaflet.Map(zoom=3)
m.layout.width = "600px"
layer = ipyleaflet.GeoJSON()
m.add(layer)


@ipywidgets.interact(item=items)
def browse(item):
    shape = shapely.geometry.shape(item.geometry)
    m.center = tuple(shape.centroid.coords[0])[::-1]

    layer.data = item.geometry
    print(item.id, item.datetime.isoformat())


m

Here's an example of using the browser: