Parameters

Parameter Reference

Complete parameter reference for all LIRiAP algorithms.

Common Parameters

Input/Output

Parameter	Type	Description	Applies To
INPUT	VectorLayer	Input polygon layer	All
OUTPUT	FeatureSink	Output rectangle layer	All

Search Control

Parameter	Type	Default	Description
GRID_COARSE	Integer	40	Initial grid resolution for coarse search (Approximation, Skeleton, BCRS)
GRID_FINE	Integer	100/120	Fine grid resolution for refinement
ANGLE_STEP	Double	5.0	Fallback sweep angle step in degrees
TOP_K	Integer	3	Number of angle candidates to keep for refinement (Skeleton, BCRS)

Constraint

Parameter	Type	Default	Description
MAX_RATIO	Double	1.6	Maximum aspect ratio (long:short), 0 = unlimited

Containment

Parameter	Type	Default	Description
ALWAYS_RETURN	Boolean	True	Return best-effort rectangle if strict certification fails
USE_BUFFER	Boolean	False	Apply containment buffer after certification
BUFFER_VALUE	Double	-0.5	Buffer distance in map units (negative = inward)

Performance

Parameter	Type	Default	Description
N_WORKERS	Integer	1	Workers (0 = auto, 1 = serial, >1 = parallel)
USE_CHUNKING	Boolean	False	Enable chunked parallel execution
AUTO_INSTALL_NUMBA	Boolean	False	Attempt Numba auto-install if missing

Axis-Aligned Specific

Parameter	Type	Default	Description
AXIS_ANGLE	Double	0.0	Rotation of axis-aligned frame in degrees

Algorithm-Specific Defaults

Algorithm	GRID_COARSE	GRID_FINE	TOP_K	ANGLE_STEP
Approx Standard	40	100	1	5.0
Approx Fast	40	100	1	5.0
Skeleton	40	40	5	5.0
BCRS	40	120	3	5.0
BCRS Fast	40	120	3	5.0
Axis-Aligned	N/A	120 (fallback)	N/A	N/A

Parameter Effects

GRID_COARSE / GRID_FINE

• Higher values → more accurate results, slower execution
• Trade-off: quadratic time complexity in grid size

ANGLE_STEP

• Smaller values → more angle candidates, slower but potentially more accurate
• Affects fallback sweep only (primary candidates from edge directions)

TOP_K

• Higher values → more candidates refined, slower but potentially better
• Must be >= 1

MAX_RATIO

• Lower values → more constrained shapes, may reduce max area
• 0 = no limit

ALWAYS_RETURN

• True: Always return a rectangle (may be smaller if best-effort used)
• False: Return nothing if strict certification fails

N_WORKERS

• 1: Serial execution

• 1: Parallel execution (per-feature or chunked)

• 0: Auto-detect CPU count

USE_CHUNKING

• True: Chunk-based parallel (better for canceling)
• False: Per-feature parallel

Output Fields

Approximation

Field	Type	Description
feat_id	int	Source feature ID
area	double	Rectangle area
angle	double	Rotation angle (degrees)
ratio	double	Aspect ratio

Skeleton / BCRS

Field	Type	Description
feat_id	int	Source feature ID
area	double	Rectangle area
angle	double	Rotation angle (degrees)
ratio	double	Aspect ratio
cand_rank	int	Rank of selected candidate
s2_gain	double	Area gain from Stage 2
s4_gain	double	Area gain from Stage 4 (BCRS only)
s5_gain	double	Area gain from Stage 5 (BCRS only)
best_effort	int	1 if fallback used

Axis-Aligned

Field	Type	Description
feat_id	int	Source feature ID
area	double	Rectangle area
axis_angle	double	Axis angle (echoes input)
poly_type	string	Polygon type classification
ratio	double	Aspect ratio
best_effort	int	1 if fallback used