Configuration Guide

All radsym algorithms are controlled through plain structs with public fields and sensible defaults. This page collects every config struct, organized by pipeline stage.

Proposal stage

FrstConfig

Field	Type	Default	Description
`radii`	`Vec<u32>`	`[3, 5, 7, 9, 11]`	Discrete radii to test (pixels)
`alpha`	`f32`	`2.0`	Radial strictness exponent
`gradient_threshold`	`f32`	`0.0`	Minimum gradient magnitude for voting
`polarity`	`Polarity`	`Both`	Target polarity (Bright, Dark, Both)
`smoothing_factor`	`f32`	`0.5`	Gaussian sigma = factor * radius

RsdConfig

Field	Type	Default	Description
`radii`	`Vec<u32>`	`[3, 5, 7, 9, 11]`	Discrete radii to test (pixels)
`gradient_threshold`	`f32`	`0.0`	Minimum gradient magnitude for voting
`polarity`	`Polarity`	`Both`	Target polarity
`smoothing_factor`	`f32`	`0.5`	Gaussian sigma = factor * radius

NmsConfig

Field	Type	Default	Description
`radius`	`usize`	`5`	Suppression half-window size (pixels)
`threshold`	`f32`	`0.0`	Minimum response to consider
`max_detections`	`usize`	`1000`	Budget cap on returned peaks

HomographyRerankConfig

Field	Type	Default	Description
`min_radius`	`f32`	`6.0`	Minimum image-space radius to evaluate
`max_radius`	`f32`	`0.0`	Maximum radius (0.0 = auto)
`radius_step`	`f32`	`2.0`	Coarse radius sweep step (pixels)
`ray_count`	`usize`	`64`	Image-space rays for edge acquisition
`radial_search_inner`	`f32`	`0.6`	Inner factor for radial search
`radial_search_outer`	`f32`	`1.45`	Outer factor for radial search
`size_prior_sigma`	`f32`	`0.22`	Gaussian size prior width
`center_prior_sigma_fraction`	`f32`	`0.45`	Center prior sigma as fraction of image size

Scoring stage

AnnulusSamplingConfig

Field	Type	Default	Description
`num_angular_samples`	`usize`	`64`	Angular sample count around annulus
`num_radial_samples`	`usize`	`9`	Radial sample count across annulus width

ScoringConfig

Field	Type	Default	Description
`sampling`	`AnnulusSamplingConfig`	(see above)	Annulus sampling parameters
`annulus_margin`	`f32`	`0.3`	Fractional width around hypothesized radius
`min_samples`	`usize`	`8`	Minimum samples to avoid degeneracy
`weight_ringness`	`f32`	`0.6`	Weight for gradient alignment component
`weight_coverage`	`f32`	`0.4`	Weight for angular coverage component

RadialCenterConfig

Field	Type	Default	Description
`patch_radius`	`usize`	`12`	Half-width of the analysis patch (pixels)
`gradient_threshold`	`f32`	`1e-4`	Minimum gradient magnitude for fit

CircleRefineConfig

Field	Type	Default	Description
`max_iterations`	`usize`	`10`	Maximum refinement iterations
`convergence_tol`	`f32`	`0.1`	Stop when center shift < this (pixels)
`annulus_margin`	`f32`	`0.3`	Annulus width as fraction of radius
`radial_center`	`RadialCenterConfig`	(see above)	Sub-step center config
`sampling`	`AnnulusSamplingConfig`	(see above)	Sub-step sampling config

EllipseRefineConfig

Field	Type	Default	Description
`max_iterations`	`usize`	`5`	Maximum refinement iterations
`convergence_tol`	`f32`	`0.1`	Convergence threshold (pixels)
`annulus_margin`	`f32`	`0.3`	Annulus margin for diagnostics
`radial_center`	`RadialCenterConfig`	(see above)	Seed stabilization config
`sampling`	`AnnulusSamplingConfig`	(see above)	Legacy sampling config
`min_alignment`	`f32`	`0.3`	Minimum alignment for diagnostics
`ray_count`	`usize`	`96`	Angular sectors for edge acquisition
`radial_search_inner`	`f32`	`0.6`	Inner radius factor for initial search
`radial_search_outer`	`f32`	`1.45`	Outer radius factor for initial search
`normal_search_half_width`	`f32`	`6.0`	Normal search window (pixels)
`min_inlier_coverage`	`f32`	`0.6`	Minimum sector coverage of inliers
`max_center_shift_fraction`	`f32`	`0.4`	Max center shift / seed radius
`max_axis_ratio`	`f32`	`1.8`	Maximum allowed a/b ratio

HomographyEllipseRefineConfig

Field	Type	Default	Description
`max_iterations`	`usize`	`5`	Maximum refinement iterations
`convergence_tol`	`f32`	`0.1`	Convergence threshold (rectified pixels)
`radial_center`	`RadialCenterConfig`	(see above)	Image-space seed stabilization
`ray_count`	`usize`	`96`	Image-space rays for edge acquisition
`radial_search_inner`	`f32`	`0.6`	Inner radius factor
`radial_search_outer`	`f32`	`1.45`	Outer radius factor
`normal_search_half_width`	`f32`	`6.0`	Normal search window (pixels)
`min_inlier_coverage`	`f32`	`0.45`	Minimum rectified angular coverage
`max_center_shift_fraction`	`f32`	`0.4`	Max center shift / rectified radius
`max_radius_change_fraction`	`f32`	`0.6`	Max radius change / rectified radius

Tuning tips

Small targets (radius < 10 px): Use tight radii in FrstConfig (e.g., [3, 5, 7]), reduce patch_radius in RadialCenterConfig, and lower normal_search_half_width in EllipseRefineConfig.

Noisy images: Increase gradient_threshold in FrstConfig/RsdConfig to suppress votes from noise. Increase smoothing_factor for broader peaks that survive noise.

High-precision localization: Increase ray_count in EllipseRefineConfig for denser angular sampling. Decrease convergence_tol to force more refinement iterations. Use a larger patch_radius in RadialCenterConfig.

Real-time budgets: Use RsdConfig instead of FrstConfig for faster proposal generation. Set max_detections in NmsConfig to limit downstream work. Reduce ray_count and max_iterations in refinement configs.

Strong perspective distortion: Use the homography-aware path (HomographyEllipseRefineConfig) when a calibrated homography is available. Otherwise, increase max_axis_ratio in EllipseRefineConfig to permit more eccentric ellipses.

radsym: Radial Symmetry Detection