Terms and definitions

3D asset

The combination of an object’s 3D geometry, assigned material properties, and specific metadata.

3D model

A mathematical coordinate-based representation of an object’s geometrical surface. Material properties used for rendering purposes can be part of the 3D model. This excludes physical material properties. For a combination of 3D geometry and physical material properties, see 3D asset.

3D environment

A 3D representation of a simulated sensor’s surroundings. It can consist of multiple 3D assets.

Co-simulation

Simulation of multiple independent models connected with interfaces. A co-simulation platform handles the timing, synchronization, and data transfer between the individual models.

Ground truth

Defines true static and dynamic states of objects. The true states are either determined by the content creator or defined by an omniscient observer, for example, a simulation platform.

Machine perception

The ability of systems to interpret sensory data and to reliably detect objects and other road users relevant to the operation of automated driving. The data is used to generate situational awareness of the vehicle environment.

Source: Klaus Dietmayer, Predicting of Machine Perception for Automated Driving, 2016

Material

A collection of material properties belonging to one entity.

Material assignment

A mapping of material IDs to meshes of 3D models, or pixels of textures mapped to these meshes. The material ID is a unique pointer to a set of material properties in separate material files.

Material classification

Standardized classification scheme that sorts materials into classes and groups of classes, for example, based on their physical properties.

Material parameter file

A file in JSON format containing defined material properties according to the OpenMATERIAL standard.

Material property

Denotes a physical, chemical, or geometric property of a material.

Multispectral/hyperspectral material

Material with wavelength-specific properties that are defined for multiple spectra.

Multispectral material shows up in imagery as 3-10 wider bands.

Hyperspectral material shows hundreds of narrow bands.

Object

A tangible thing with defined 3D boundaries and discrete meshes. An object ID can be assigned.

Object part

A segment of an object that has distinct characteristics, for example, material, shape, or function.

Example: A car door differs from the rest of the vehicle due to its function to open and close.

Object type

Class of objects with the same set of properties. Each instance of the class is described by the same properties, but has individual property values.

Physical property

Denotes a characteristic of an object or material that can be measured. Examples: permittivity, density, index of refraction.

Post rendering effect

Visual modification applied to graphics after initial rendering, enhancing appearance or realism without impairing performance.

Scenario

A description of the behavior or temporal evolution of physical objects and environmental conditions on the driving infrastructure over an interval of time, including the movement of traffic participants or the change of environmental conditions.

Source: ASAM OpenSCENARIO v1.3.0 standard, 2024

Signal energy propagation

The act of a signal traveling through the environment and potentially interacting with objects and particles.

Source: Linnhoff et al., Towards Serious Perception Sensor Simulation for Safety Validation of Automated Driving - A Collaborative Method to Specify Sensor Models, 2021

Simulation platform

Application that orchestrates and runs the simulations. It can be either an all-in-one solution including the generation of the 3D environment or a co-simulation platform orchestrating a co-simulation of multiple sensor models, vehicle dynamics models, and so on.

Surface normal

A vector that is perpendicular to a given object, surface, or geometrical primitive. It can be used to determine the face direction for 2D and 3D rendering.

Validation

A method for evaluating a simulation model’s performance and accuracy by comparing simulated data to measured data and quantifying the differences.

Vertex normal

A directional vector that is associated with a vertex. It represents the normalized average of the surrounding surface normals.