boxes_from_polygons#

geowombat.detect.boxes_from_polygons(gdf, oriented=False)[source]#

Convert polygon geometries to bounding-box geometries.

Two flavors of bounding box are supported:

  • Axis-aligned (AABB) — oriented=False (default). Sides parallel to the image axes. Right for objects that line up with the grid: buildings in a nadir aerial frame, cars in a parking lot, parcels.

  • Oriented (OBB) — oriented=True. Minimum rotated rectangle around each polygon. Right for objects that appear at arbitrary angles in overhead imagery — ships, planes on a tarmac, vehicles on diagonal roads, storage tanks viewed off-nadir.

For overhead / aerial work, OBB is almost always the better choice and should be paired with weights pretrained on the DOTA-v1 benchmark (e.g. yolov8n-obb.pt). Mixing OBB labels with non-OBB weights will fail at training time.

Quality of OBB output depends on the input polygon. The minimum rotated rectangle uses the polygon’s extreme points, so loose blob-shaped digitization yields a sloppy OBB. Trace tightly along the object’s long axis when labeling.

Parameters:
gdfgeopandas.GeoDataFrame

Input labels. Geometries may be Polygon or MultiPolygon. Pass-through for any geometry that is already a box.

orientedbool

If True, return minimum rotated rectangles (4-corner polygons). If False, return axis-aligned envelopes (default).

Returns:
geopandas.GeoDataFrame

Same columns as input with geometries replaced by boxes. A new column _box_kind is added: 'aabb' or 'obb'.

See also

build_yolo_dataset

Calls this internally when oriented=True.