Pipelines

This section documents each target’s complete, end-to-end detection pipeline — one page per target type. Where the Algorithms section describes each building block in isolation, a pipeline page shows how a particular target composes those blocks from a grayscale image (or a pre-detected corner cloud) to a labelled, ID-carrying detection.

Each pipeline page narrates and links the canonical stage map that lives next to the code. The crate-level docs/PIPELINE.md files are the source of truth; these pages mirror them and must not diverge.

The shared front-end

Every detector shares the same first three steps:

┌───────────┐    ┌───────────┐    ┌───────────┐    ┌───────────┐
│  Image    │ -> │  ChESS    │ -> │ Target-   │ -> │ Labelled  │
│ (u8 gray) │    │ corners   │    │ specific  │    │ grid out  │
└───────────┘    │ (front-   │    │ detector  │    │           │
                 │  end)     │    │           │    │           │
                 └───────────┘    └───────────┘    └───────────┘

1. Input image — image::GrayImage or a GrayImageView. The facade helpers in calib_targets::detect accept either.
2. Corner front-end — the ChESS X-junction detector via the chess-corners crate produces a raw corner cloud (sub-pixel position + two undirected axes, each with a 1σ angular uncertainty + a strength response magnitude). The workspace default is calib_targets::detect::default_chess_config().
3. Grid recovery — every target then runs the same grid stack: axis clustering → the topological grid finder → recovery & validation. This is the chessboard pipeline, and it is the shared spine of all the others.
4. Target-specific decode + IDs — self-identifying targets add their own decoder (ArUco bits, PuzzleBoard edge codes) and ID assignment on top of the recovered grid.
5. Output — every detector produces a TargetDetection wrapping a Vec<LabeledCorner>; higher-level detectors wrap that in their own result struct with extra metadata (marker decodes, alignment, IDs). See Understanding Results.

The pages

One builder, everywhere

There is no grid-builder choice or selector to configure: the topological grid finder is the sole builder for every target, including ChArUco. Legacy config keys for removed builder selectors are rejected as unknown fields.

Output types

Output types are standardised in calib-targets-core as TargetDetection with LabeledCorner values. The chessboard layer’s labelling carries the precision contract every target inherits: wrong (i, j) labels are unrecoverable for downstream calibration, so the grid stage may fail to detect a corner but must never deliver a wrong label. Higher-level crates enrich that output with additional metadata (marker detections, rectified views, per-corner IDs).