JensandClaude Opus 5
dd87a62e8f
Four ways a selection produced a confident number about a different area than the operator drew: Flood hazard divided the inundated cells by every cell in the drawn rectangle, including cells the VMM raster does not model at all. A selection reaching past the modelled extent therefore reported a diluted risk share, turning missing data into an implied absence of risk. Terrain, bathymetry and thematic raster already divided by valid cells; flood hazard was the outlier. It now reports the three populations separately, states model coverage next to the drawn area, and returns a null fraction rather than a zero when nothing was modelled. geometry_mask selects a cell when its centre falls inside the geometry, so a rectangle smaller than one cell — or one landing between four centres — selected nothing and the analysis returned zeros indistinguishable on screen from "we looked and there is nothing here". On a 100 m population raster a 40 m rectangle over a city block reported no inhabitants. Selection now falls back to the touched cells and says that it did, since the answer then covers more ground than was requested. rasterio.mask applies the same centre rule when cropping, so that call is widened too; the cells that count are still decided by the centre rule wherever it selects anything. The object count treated any feature touching the selection as whole, while intersection_area clipped it — two headline numbers on one panel describing different populations. The count stays whole-feature, which is what "objecten" means to an operator, but now reports how many the edge cuts and is marked an estimate when it does. The area_weighted_sum branch reuses that same count instead of issuing its own near-identical query. Partitioned selection de-duplicated the count on source_feature_id but returned the raw rows, so a building on a municipal boundary was counted once and drawn twice. Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
85 lines
3.0 KiB
Python
85 lines
3.0 KiB
Python
"""A selection smaller than a raster cell must not silently read as zero.
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``geometry_mask`` selects a cell when its *centre* falls inside the geometry.
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A rectangle smaller than one cell, or one that lands between four centres,
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therefore selects nothing at all — and the analysis returned zeros, which on
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screen is indistinguishable from "we looked and there is nothing here". On a
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100 m population raster a 40 m rectangle over a city block reported no
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inhabitants.
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Selection now falls back to every touched cell and says that it did, so the
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value is readable as "at least one whole cell", not as an empty area.
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"""
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from __future__ import annotations
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import pytest
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np = pytest.importorskip("numpy")
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rasterio = pytest.importorskip("rasterio")
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from rasterio.transform import from_origin
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from shapely.geometry import box
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from app.services.raster_cell_selection import select_cells
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# 100 m cells, origin at the top-left corner of a 3x3 grid.
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TRANSFORM = from_origin(200_000, 210_000, 100.0, 100.0)
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SHAPE = (3, 3)
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def test_a_normal_selection_uses_cell_centres() -> None:
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selection = select_cells(box(200_000, 209_700, 200_300, 210_000), out_shape=SHAPE, transform=TRANSFORM)
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assert selection.mask.sum() == 9
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assert selection.mode == "cell_centre"
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assert selection.expanded_to_touched_cells is False
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assert selection.warning is None
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def test_a_rectangle_smaller_than_one_cell_still_returns_that_cell() -> None:
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selection = select_cells(box(200_010, 209_960, 200_050, 209_990), out_shape=SHAPE, transform=TRANSFORM)
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assert selection.mask.sum() == 1
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assert selection.mode == "all_touched"
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assert selection.expanded_to_touched_cells is True
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assert "cel" in selection.warning
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def test_a_rectangle_between_four_cell_centres_returns_all_four() -> None:
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selection = select_cells(box(200_080, 209_880, 200_120, 209_920), out_shape=SHAPE, transform=TRANSFORM)
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assert selection.mask.sum() == 4
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assert selection.expanded_to_touched_cells is True
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def test_a_selection_entirely_off_the_raster_selects_nothing() -> None:
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"""Falling back must not invent coverage where the geometry does not reach."""
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selection = select_cells(box(300_000, 300_000, 300_100, 300_100), out_shape=SHAPE, transform=TRANSFORM)
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assert selection.mask.sum() == 0
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assert selection.expanded_to_touched_cells is False
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assert selection.mode == "cell_centre"
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def test_the_warning_states_how_much_larger_the_analysed_area_is() -> None:
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selection = select_cells(
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box(200_010, 209_960, 200_050, 209_990),
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out_shape=SHAPE,
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transform=TRANSFORM,
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cell_area_m2=100.0 * 100.0,
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)
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# One 100x100 m cell was analysed for a 40x30 m request.
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assert "1 rastercel" in selection.warning
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assert "1.0 ha" in selection.warning
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def test_the_mask_shape_always_matches_the_raster_window() -> None:
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selection = select_cells(box(200_010, 209_960, 200_050, 209_990), out_shape=SHAPE, transform=TRANSFORM)
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assert selection.mask.shape == SHAPE
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assert selection.mask.dtype == np.bool_
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