Create an InSAR Item¶

Install the package before running this complete example. It creates a synthetic interferogram Item with acquisition dates, baselines, and DEM identifiers.

from datetime import datetime, timezone

import pystac
from pystac.extensions.insar import InsarExtension

reference_datetime = datetime(2023, 2, 1, tzinfo=timezone.utc)
secondary_datetime = datetime(2023, 2, 13, tzinfo=timezone.utc)
item = pystac.Item(
    id="example-interferogram",
    geometry=None,
    bbox=None,
    datetime=secondary_datetime,
    properties={"title": "Synthetic InSAR example"},
)
insar = InsarExtension.ext(item, add_if_missing=True)
insar.apply(
    perpendicular_baseline=123.4,
    temporal_baseline=12,
    height_of_ambiguity=42,
    reference_datetime=reference_datetime,
    secondary_datetime=secondary_datetime,
    processing_dem="COP-DEM GLO-30",
    geocoding_dem="COP-DEM GLO-30",
)

serialized = item.to_dict()
assert InsarExtension.get_schema_uri() in serialized["stac_extensions"]
assert serialized["properties"]["insar:temporal_baseline"] == 12.0
assert serialized["properties"]["insar:reference_datetime"] == "2023-02-01T00:00:00Z"

restored_item = pystac.Item.from_dict(serialized)
restored = InsarExtension.ext(restored_item)
assert restored.reference_datetime == reference_datetime
assert restored.secondary_datetime == secondary_datetime
assert restored.processing_dem == insar.processing_dem

The numeric setters store floats. Datetime setters serialize Python datetimes to strings; getters convert them back to datetimes. Use timezone-aware datetimes to make acquisition times explicit.

This example uses the secondary acquisition as the core Item datetime. The wrapper does not choose the core timestamp or calculate a temporal baseline from acquisition dates; callers supply those values.

to_dict() serializes the Item without running JSON Schema validation. See validation boundaries for the distinction.