Frame Graph

This guide covers Vulcan's frame-tree API for extensible coordinate transforms:

• FrameRegistry stores frame topology.
• TransformProvider defines child/parent math per edge.
• FrameContext<Scalar> ties topology and providers together.

Quick Start

#include <vulcan/vulcan.hpp>
 
using namespace vulcan;
 
FrameContext<double> ctx;
ctx.set_ecef(ConstantOmegaRotation::from_wgs84(), 3600.0);
ctx.set_ned(-77.0367 * constants::angle::deg2rad,
            38.8951 * constants::angle::deg2rad);
ctx.set_body_euler(45.0 * constants::angle::deg2rad,
                   5.0 * constants::angle::deg2rad,
                   10.0 * constants::angle::deg2rad);
 
Vec3<double> v_body;
v_body << 100.0, 0.0, 0.0;
 
Vec3<double> v_ned = ctx.transform(v_body, FRAME_BODY, FRAME_NED);
Vec3<double> v_eci = ctx.transform(v_body, FRAME_BODY, FRAME_ECI);

Built-In Hierarchy

Default tree (FrameRegistry::default_aerospace()):

• ECI (root)
• ECEF child of ECI
• NED, ENU, Geocentric, Rail, CDA children of ECEF
• Body child of NED
• Wind, Stability children of Body

Custom Frames

auto sensor_q =
    janus::Quaternion<double>::from_euler(0.0, 10.0 * constants::angle::deg2rad, 0.0);
auto sensor_id = ctx.add_frame(
    "Sensor",
    FRAME_BODY,
    std::make_shared<QuaternionProvider<double>>(sensor_q));
 
Vec3<double> v_sensor;
v_sensor << 1.0, 0.0, 0.0;
auto v_ned_from_sensor = ctx.transform(v_sensor, sensor_id, FRAME_NED);

Symbolic Usage

FrameContext is templated and works with SymbolicScalar:

FrameContext<SymbolicScalar> sym_ctx;
auto gmst = sym("gmst");
auto lon = sym("lon");
auto lat = sym("lat");
auto yaw = sym("yaw");
auto pitch = sym("pitch");
auto roll = sym("roll");
 
sym_ctx.set_ecef(gmst);
sym_ctx.set_ned(lon, lat);
sym_ctx.set_body_euler(yaw, pitch, roll);

Backward Compatibility

Existing APIs remain unchanged:

• CoordinateFrame<Scalar>
• transform_vector(...)
• body_from_euler(...)
• lla_to_ecef(...) / ecef_to_lla(...)

Use FrameContext when you need automatic multi-hop traversal or custom frame registration.