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geointel/backend/tests/test_change_detection_modified_features.py
T
JensandClaude Opus 5 23d6e0372b distinguish a redrawn footprint from a demolition, and derive estimate
disclosure from data

Change detection had only added/removed/unchanged, so a building extended by
an annexe dropped below the IoU threshold and was reported twice: once as
removed and once as added. That hides exactly the category a change-detection
product exists to show and inflates both counts. A "modified" class now covers
the band between the modified floor and the unchanged threshold.

Matching also ran as a full cross product with no spatial index, unlike the QA
matcher beside it: two municipal building layers meant hundreds of millions of
geometry intersections. It uses an STRtree and considers larger footprints
first, so a big footprint is not left over after a small neighbour claimed its
counterpart.

The assistant guaranteed honesty about estimated values by rewriting the
model's sentences with regular expressions, which only fires when it
recognises the phrasing the model happened to produce. estimate_disclosures
derives the same statement from the metric metadata, so it holds regardless of
how the answer was worded. The prose substitution stays as a second layer.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
2026-08-22 14:33:37 +02:00

115 lines
3.9 KiB
Python

"""An extended building is a change, not a deletion plus a new building.
With only added/removed/unchanged, a footprint that grew by an annexe drops
below the IoU threshold and is reported twice: once as removed and once as
added. That hides exactly the category a change-detection product exists to
show, and inflates both counts.
"""
from __future__ import annotations
import pytest
from shapely.geometry import box
from app.services.change_detection_service import ChangeDetectionService
def _feature(feature_id: str, geometry):
return {"feature_id": feature_id, "properties": {}, "geometry": geometry}
def _classify(source, target, *, iou_threshold=0.8, modified_threshold=0.3):
return ChangeDetectionService._classify_features(
source,
target,
iou_threshold=iou_threshold,
modified_threshold=modified_threshold,
)
def test_an_extended_footprint_is_reported_as_modified() -> None:
source = [_feature("b1", box(0, 0, 10, 10))]
target = [_feature("b1-new", box(0, 0, 10, 14))] # IoU 100/140 = 0.71
result = _classify(source, target)
assert [item["change_type"] for item in result] == ["modified"]
assert result[0]["source_feature_id"] == "b1"
assert result[0]["target_feature_id"] == "b1-new"
assert result[0]["iou"] == pytest.approx(100 / 140)
def test_a_nearly_identical_footprint_is_unchanged() -> None:
source = [_feature("b1", box(0, 0, 10, 10))]
target = [_feature("b1", box(0, 0, 10, 10.2))]
result = _classify(source, target)
assert [item["change_type"] for item in result] == ["unchanged"]
def test_a_genuinely_new_building_stays_added() -> None:
source = [_feature("b1", box(0, 0, 10, 10))]
target = [_feature("b1", box(0, 0, 10, 10)), _feature("b2", box(50, 50, 60, 60))]
result = _classify(source, target)
assert sorted(item["change_type"] for item in result) == ["added", "unchanged"]
def test_a_demolished_building_stays_removed() -> None:
source = [_feature("b1", box(0, 0, 10, 10)), _feature("b2", box(50, 50, 60, 60))]
target = [_feature("b1", box(0, 0, 10, 10))]
result = _classify(source, target)
assert sorted(item["change_type"] for item in result) == ["removed", "unchanged"]
def test_barely_overlapping_footprints_are_not_called_modified() -> None:
"""Below the modified floor the two are separate objects, not one changed."""
source = [_feature("b1", box(0, 0, 10, 10))]
target = [_feature("b2", box(9, 9, 19, 19))] # IoU ~0.005
result = _classify(source, target)
assert sorted(item["change_type"] for item in result) == ["added", "removed"]
def test_each_target_is_claimed_at_most_once() -> None:
source = [_feature("a", box(0, 0, 10, 10)), _feature("b", box(0, 0, 10, 12))]
target = [_feature("t", box(0, 0, 10, 10))]
result = _classify(source, target)
claimed = [item for item in result if item["target_feature_id"] == "t"]
assert len(claimed) == 1
def test_classification_is_independent_of_input_order() -> None:
source = [_feature("a", box(0, 0, 10, 10)), _feature("b", box(30, 30, 40, 40))]
target = [_feature("a2", box(0, 0, 10, 14)), _feature("c", box(70, 70, 80, 80))]
forward = _classify(source, target)
reverse = _classify(list(reversed(source)), list(reversed(target)))
def signature(items):
return sorted(
(item["change_type"], item["source_feature_id"], item["target_feature_id"]) for item in items
)
assert signature(forward) == signature(reverse)
def test_large_populations_do_not_use_a_full_cross_product() -> None:
"""A spatial index keeps a city-sized comparison tractable."""
source = [_feature(f"s{i}", box(i * 10, 0, i * 10 + 8, 8)) for i in range(400)]
target = [_feature(f"t{i}", box(i * 10, 0, i * 10 + 8, 8)) for i in range(400)]
result = _classify(source, target)
assert all(item["change_type"] == "unchanged" for item in result)
assert len(result) == 400