Coordinate Frame Federation Across Mesh Regions

Mechanism

Each coordinate frame in the federated mesh is a first-class governed object. A frame declaration specifies the frame's identifier, its mathematical definition (datum, projection, units, orientation conventions), the authority competent to maintain the declaration, and the admissibility rules under which observations expressed in the frame may be consumed by other frames. Frames are not interchangeable; a coordinate triple is meaningful only when paired with the frame in which it is expressed. The federation infrastructure refuses to accept bare coordinates lacking a frame reference, and refuses to silently coerce coordinates from one frame into another.

Composition between frames is mediated by credentialed transformations. A transform from frame A to frame B is a tuple of (source frame identifier, target frame identifier, transformation parameters, validity region, validity epoch, uncertainty model, signing authority, signature). The signing authority is the entity competent to declare the transform: a national geodetic agency for a datum-to-datum transform, a state surveyor for a state plane to local survey transform, a platform integrator for a body-relative to local frame transform. The signature binds the transform to its authority and to the epoch of declaration, allowing downstream consumers to verify provenance without trusting an intermediate registry.

A cross-frame observation, such as a sensor measurement that resolves a target position in frame A while the observer's pose is known in frame B, is admitted only when transforms covering the operation are available, signed by competent authorities, and valid at the observation epoch within the relevant region. The federation evaluator chains transforms as needed: a body-relative observation may chain through a local survey frame and a state plane projection to reach a WGS84 representation, with each link in the chain contributing its own uncertainty and each requiring its own admissible signature. If any link fails admissibility, the chain is rejected and the observation is recorded as cross-frame inadmissible rather than silently dropped.

Authority binding is the structural property that distinguishes the disclosed federation from a generic transform library. Each transform is meaningful only within the scope of the authority that signed it, and the federation evaluator refuses to substitute one authority for another even when the numerical transformation would be identical. A state-plane-to-WGS84 transform signed by a national geodetic agency is not interchangeable with the same transformation produced by a third-party calibration, because their validity regions, epochs, and uncertainty models are declarations of the signing authority and are not transferable. This rigidity is intentional: it ensures that the operational provenance of every cross-frame inference is traceable to a competent declaration, and that consumers downstream of the federation can rely on the declared uncertainty bounds without performing their own re-validation of the underlying transform.

Operating Parameters

Frame declarations are bounded in number per deployment. A typical mesh maintains tens of frames: one or two geodetic datums, several projected frames for the regions covered, a set of local survey frames per facility, and one body-relative frame per platform class. Transform declarations scale with the connectivity between frames; the federation does not require a complete graph, only that operationally needed pairs are reachable through admissible chains. Validity regions are expressed as polygonal or geodesic bounds; validity epochs are expressed as ranges with explicit expiry. Uncertainty models are typically Gaussian with frame-specific covariance scaling, but the architecture admits non-Gaussian and bounded-error models when the signing authority declares them.

Transform refresh cadence is parameterized per transform. Static transforms (state plane to WGS84) refresh on the cadence of geodetic adjustment cycles, which is years. Semi-static transforms (local survey to state plane) refresh on the cadence of survey campaigns. Dynamic transforms (body-relative to local) refresh continuously as the platform moves; their signature is delegated to the platform's onboard authority and renewed at the cadence of the platform's pose-estimation update. The federation evaluator caches transforms with explicit expiry and refuses chains that include any expired link.

Chain length is bounded operationally rather than mathematically. A chain that traverses many intermediate frames accumulates uncertainty multiplicatively and accumulates authority dependencies additively; deployments declare a maximum acceptable chain length and a maximum acceptable accumulated uncertainty per use case, and the evaluator refuses chains that exceed either bound even when each link is individually admissible. Direct transforms between commonly co-used frame pairs are cached preferentially, and missing direct transforms are flagged to the relevant authorities as candidates for promulgation. The architecture admits asymmetric transforms (frame A to B may differ from B to A in uncertainty model or validity region) and refuses to synthesize an inverse from a forward declaration unless the signing authority has explicitly declared the inverse admissible.

Alternative Embodiments

In a first embodiment, all transform signatures are produced by a centralized federation registry that brokers between authorities. In a second embodiment, signatures are produced directly by each declaring authority, and the registry is purely a discovery service that holds no signing keys. In a third embodiment, transform declarations are committed to an append-only ledger maintained jointly by the participating authorities, with cross-signatures producing a multi-party endorsement. Each embodiment trades centralization against trust distribution; the disclosed mechanism is agnostic to the specific signature infrastructure provided that authority binding is preserved.

Variant frame inventories are admitted. A deployment may include time-varying frames (such as a tectonic-plate-fixed frame for high-precision geodesy), trajectory frames (a frame attached to a moving reference platform), or sensor-intrinsic frames (a frame defined by a calibration of a specific sensor). Variant uncertainty propagation includes linear covariance propagation, unscented transform propagation for nonlinear chains, and Monte Carlo propagation for non-Gaussian chains. Variant validity-region representations include axis-aligned bounding boxes, convex polygons, geodesic polygons, and discrete grid cells.

Composition

Frame federation composes with the broader mesh-coordinate architecture by serving as the substrate over which positional admissibility is evaluated. A positional claim that crosses frames is admissible only if the chain of transforms required to express the claim in the consumer's frame is itself admissible: every link signed by a competent authority, every signature valid at the operation epoch, every validity region containing the operation locus. This means that frame federation is not a convenience layer that hides coordinate conversion; it is a governance layer that refuses conversion when authority is missing, and surfaces the missing authority to the operator rather than producing a numerically plausible but unauthorized coordinate.

Composition with the mesh anchor system pairs each anchor with a declared frame and with the transform set that connects its frame to the frames of operationally adjacent anchors. Composition with the sensor admission subsystem ensures that sensors declare the frame in which their measurements are expressed at calibration time, and that any rebinning of a sensor to a new frame is itself a governed operation. Composition with the operational lineage records every cross-frame admission as a tuple of (source frame, target frame, transform chain hashes, signatures verified, observation outcome), allowing auditors to confirm that every cross-frame inference was supported by an admissible chain at the time it was drawn.

The federation also composes with multi-jurisdictional deployment patterns. Cross-border autonomous-vehicle corridors, multi-national operating regions, and federated industrial campuses each present a configuration in which different authorities are competent over different segments of the operational space. Frame federation accommodates these patterns by allowing each jurisdiction to maintain its own frame declarations and its own transforms while exposing boundary transforms that are jointly signed by the adjacent jurisdictions. Operations crossing the boundary consume the joint transform; operations remaining within a single jurisdiction consume only intra-jurisdiction transforms. Gradual deployment scale is supported by the same mechanism: a new region enters the federation by negotiating boundary transforms with its neighbors, and existing regions are unaffected until and unless they need to interoperate with the new region. The architecture therefore supports growth without forcing global re-coordination, and supports jurisdictional autonomy without forcing operational fragmentation.

Prior-Art Distinction

Geographic information systems support transforms between coordinate reference systems through libraries such as PROJ, but these libraries treat transforms as numerical functions rather than as signed governed objects, and they do not gate operations on transform admissibility. Robotic frame trees (such as the ROS tf2 system) compose body-relative frames into kinematic chains but lack authority binding and lineage. Geodetic registries publish official transforms but do not enforce their use as a precondition for cross-frame operations downstream. The disclosed mechanism differs in that each transform is a credentialed object whose use is gated on signature verification, that cross-frame operations refuse to proceed without an admissible chain, and that the federation produces a verifiable lineage of cross-frame inferences. No surveyed prior system combines authority binding, validity gating, and chain-level admissibility for coordinate frame composition.

Distributed ledger approaches to geospatial data have been proposed for provenance tracking but typically operate at the granularity of individual measurements rather than at the granularity of transforms, leaving the cross-frame composition step ungoverned. Map-merging algorithms in robotic SLAM produce composite frames at runtime but do not bind the merged transform to an authority and do not gate downstream consumers on the merge's admissibility. The disclosed mechanism is positioned at the transform layer specifically because that is where authority competence is naturally declared and where the composition rules become structurally enforceable.

Disclosure Scope

This disclosure covers the federation of multiple coordinate frames through credentialed, signed transforms; the admissibility evaluation of cross-frame observations against transform chains; the integration of state plane, geodetic, local survey, and body-relative frames within a single federated mesh; the validity-region and validity-epoch parameterization of transforms; and the composition with anchor, sensor, and lineage subsystems of the broader mesh architecture. The disclosure extends to any embodiment in which coordinate frames are governed objects, transforms between them are signed by competent authorities, and cross-frame operations are gated on the admissibility of the relevant transform chain, regardless of the specific signature infrastructure, uncertainty model, or registry topology employed.