📚 Glossary & Key Concepts (Alphabetical)
This glossary lists every DSG‑JIT term in strict alphabetical order for instant lookup.
A
Agent
A time‑varying entity (robot/person) with a pose trajectory over time.
Agent Pose Node
A pose node associated with a specific agent + timestamp in the DynamicSceneGraph.
B
Bearing
A unit‑direction vector from a sensor to a target (camera or LiDAR).
C
Calibration (Extrinsics)
Rigid transform from a sensor frame to the robot/base frame.
Camera Intrinsics
3×3 calibration matrix mapping pixels → normalized rays.
CameraMeasurement
Typed camera measurement containing rays, image, timestamps, etc.
Chain Residual (SE3 Chain)
Residual enforcing that a sequence of SE(3) poses matches integrated motion.
Conversion Layer (Sensor Conversion Layer)
Converts raw sensor samples into typed measurements and measurement factors.
D
DSG — Dynamic Scene Graph
A time‑varying scene graph combining geometry + semantics + temporal structure.
DSG Layer
A semantic layer (rooms, places, objects, agents, voxels, etc).
DSGTrainer
Bi‑level optimization utility (inner GN, outer hyperparameter learning).
DynamicSceneGraph
Holds time‑indexed agent poses & temporal edges.
Dynamic Voxel Field
A voxel grid that changes over time (dynamic/deformable environments).
Dataset Stream
Any sensor input driven by FunctionStream or FileRangeStream.
E
Edge (Scene Graph Edge)
Relationship between two scene‑graph nodes (room–place, place–object, etc).
Euclidean Variable
A variable in ℝⁿ (e.g., landmark, voxel, calibration scalar).
F
Factor
A residual constraint relating one or more variables.
Factor Graph
Bipartite graph of variables ↔ factors.
FileRangeStream
Sensor stream reading structured samples from a text/log file.
FunctionStream
Sensor stream driven by a Python generator function.
G
Gauss–Newton Optimization
Nonlinear least‑squares solver implemented on manifolds in DSG‑JIT.
Graph Export (SceneGraph Export)
Converts graph nodes into VisNode/VisEdge for visualization.
H
Hybrid Factor Graph
A factor graph mixing SE(3), Euclidean, and voxel variables in one optimization.
I
IMU Delta Integration (Integrate IMU Delta)
Creates a small SE(3) increment from raw IMU samples.
Inner Optimization (Inner GN / Inner Gradient Descent)
Solves the factor graph while outer parameters are fixed.
J
Jacobian
Matrix of partial derivatives of residuals wrt variable components.
JIT Compilation
JAX compilation of residual functions for high‑performance SLAM.
L
Landmark
A 3D point in the world (usually Euclidean).
Landmark Prior
Unary factor constraining a landmark near a specific 3D location.
Layered Visualization
Rendering style placing node types on separate z‑planes.
LiDAR Scan
List of ranges/angles or rays converted to LidarMeasurement.
Lie Group
Differentiable group structure for SE(3), SO(3), etc.
M
Manifold
Non‑Euclidean space (like SE(3)) requiring special update rules.
Manifold Gauss–Newton
Lie‑group‑aware Gauss–Newton with retract/exp/log operations.
Manifold Metadata
Describes each variable’s manifold type + slice in packed state vector.
Measurement
Raw or typed sensor output (camera, lidar, imu, odom).
MeasurementFactor
Factor generated from a typed measurement.
N
Named Object
Scene‑graph object with semantic identifier (e.g. “chair_1”).
O
Object Node
A semantic object (chair/table/etc) connected to a place.
Observation Model
Predicts expected sensor measurement given state x.
Odometry
Relative motion factor between two poses.
Odom_tx
1D translation‑only odom helper for quick SE(3) edges.
Outer Optimization
Top‑level hyperparameter update loop above the inner GN solver.
P
Place
A mid‑level scene‑graph node (semantic waypoint, corridor, anchor).
Place3D
3D spatial place node used in realistic indoor environments.
Place Attachment
Semantic constraint linking an agent pose → place.
Plot Functions
Graph/scene‑graph visualization utilities in world.visualization.
Pose
An SE(3) rigid transform.
R
Range
Scalar distance reading (LiDAR, UWB, depth).
Range Observation
Factor derived from a distance measurement.
Residual
Prediction error: r(x) = f(x) − z.
S
Scene Graph
Hierarchical structure representing geometry + semantics.
SceneGraphWorld
High‑level API wrapping factor graph, semantic nodes, and helpers.
SE(3) — Special Euclidean Group
Rigid‑body transform group for robot poses.
SO(3)
Rotation‑only Lie group.
Semantic Edge
High‑level symbolic edge between semantic nodes.
SensorFusionManager
Polls sensors and delivers typed measurements + callbacks.
Sensor Streams (FunctionStream / FileRangeStream)
Abstract data sources for camera/lidar/imu streams.
T
Temporal Factor
Factor connecting time‑indexed nodes.
Temporal Layer
Dynamic layer storing agent trajectories and time relations.
Trajectory (Agent Trajectory)
Ordered sequence of time‑indexed SE(3) poses.
Type Weights (Learnable Weights)
Learned weights for residual types in bi‑level training.
V
Variable
Optimizable unknown in the factor graph.
VisNode / VisEdge
Lightweight structures for 2D/3D visualization.
Voxel
Volumetric grid cell.
Voxel Grid
3D grid of voxels for dense mapping experiments.
Voxel Observation Model
Residual connecting voxel center to observed 3D point.
Voxel Smoothness Residual
Factor connecting adjacent voxels enforcing smooth geometry.
W
World Model
Top‑level container for factor graph, variables, and optimization.
Z
Zero‑Mean Gaussian Noise
Standard additive noise assumption for measurements.