Crate projective_grid 

Generic 2D projective grid graph construction, traversal, and homography tools.

This crate provides reusable algorithms for building 4- or 6-connected grid graphs from detected 2D points, assigning grid coordinates via BFS traversal, and computing projective mappings (homographies) for grid rectification.

It is pattern-agnostic: the NeighborValidator trait lets callers plug in pattern-specific logic (chessboard orientation checks, marker constraints, etc.) while the graph construction, traversal, and geometry remain generic.

Module layout

Module	Responsibility
square	Square (4-connected) grid: direction, alignment, index, mesh, rectify, smoothness, validators
hex	Hex (6-connected) grid: mirrored submodules for axial (q, r) coordinates
graph	Generic KD-tree-based graph builder + NeighborValidator trait
graph_cleanup	Graph-level cleanup passes (symmetry, straightness, crossing pruning)
global_step / local_step	Cell-size / local-step estimation on point clouds
traverse	BFS / DFS on grid graphs (connected components, (i, j) assignment)
homography	Projective geometry (4-point homography, DLT)

Top-level types from square are re-exported here at the crate root so existing consumers (e.g., projective_grid::GridIndex) continue to work unchanged.

Re-exports

pub use global_step::estimate_global_cell_size;

pub use global_step::GlobalStepEstimate;

pub use global_step::GlobalStepParams;

pub use graph::GridGraph;

pub use graph::GridGraphParams;

pub use graph::NeighborCandidate;

pub use graph::NeighborValidator;

pub use graph_cleanup::enforce_symmetry;

pub use graph_cleanup::prune_by_edge_straightness;

pub use graph_cleanup::prune_crossing_edges;

pub use graph_cleanup::prune_isolated_pairs;

pub use graph_cleanup::segments_properly_cross;

pub use homography::estimate_homography;

pub use homography::homography_from_4pt;

pub use homography::Homography;

pub use local_step::estimate_local_steps;

pub use local_step::LocalStep;

pub use local_step::LocalStepParams;

pub use local_step::LocalStepPointData;

pub use traverse::assign_grid_coordinates;

pub use traverse::connected_components;

pub use square::alignment::GridAlignment;

pub use square::alignment::GridTransform;

pub use square::alignment::GRID_TRANSFORMS_D4;

pub use square::direction::NeighborDirection;

pub use square::direction::NodeNeighbor;

pub use square::index::GridIndex;

pub use square::mesh::GridHomographyMesh;

pub use square::rectify::GridHomography;

pub use square::smoothness::find_inconsistent_corners;

pub use square::smoothness::find_inconsistent_corners_step_aware;

pub use square::smoothness::predict_grid_position;

pub use square::validators::SpatialSquareValidator;

pub use square::validators::XJunctionValidator;

Modules

circular_stats

Circular-histogram + plateau-aware peak picking + double-angle 2-means helpers.

global_step

Automatic global cell-size estimation for a 2D corner cloud.

graph

graph_cleanup

Post-build geometric sanity passes on a GridGraph.

hex

Hexagonal grid support for pointy-top axial coordinates.

homography

local_step

Generic per-corner local grid-step estimation.

square

Square (4-connected) grid support.

traverse

validators

Re-export of the square-grid submodule at the legacy validators path.

Traits

Float

Trait alias for floating-point types supported by this crate.