Glossaries

This page is a glossary for VFI, USD, and RTX terms. This resource is designed to help you understand the key terminology used across these areas. Please note that some terms, especially between VFI/CAD and USD, may appear similar but can have slightly different meanings or usage. This glossary will help clarify these overlaps and distinctions.

Virtual Factory Integration (VFI)

The following glossary provides definitions for key terms used in Virtual Factory Integration (VFI), highlighting concepts fundamental to CAD systems and manufacturing processes.

Name | Description
Product | This is the product that is sold
Part	The smallest bit in a CAD system that needs to be manufactured
Asset	An assembled unit that needs to be represented as a digital twin
Revision	A version of a part or an assembly
PMI	Product Manufacturing Information
PLM	Product Lifecycle Management
Material	A physical material, such as: Chrome Vanadium Steel, Plastic, etc
Appearance	The visual representation of a processed or non-processed part
BOM	Bill of material
Constraint	A geometrical relationship between parts limiting their relative movement
Kinematik Simulation	Simulation of the functionality without forces
Dynamic Simulation	Simulation of the functionality with forces
Greenfield	Building in the planning phase and layout is iterated on by re-exporting data to be picked up by aggregating assembly.
Brownfield	Building is mostly static, but digital twin can still pick up and changes through re-exporting data and aggregating assembly.
Work cell	Self-contained unit where people, equipment, materials, and processes are strategically grouped to efficiently perform specific manufacturing tasks in sequence, with the goal of improving workflow.

Universal Scene Description (USD)

This glossary introduces key terms and concepts used in USD.

Name	Description
Prim	A fundamental unit in USD that represents a node in the scene graph hierarchy, containing data like geometry, transforms, or other attributes.
Stage	A USD file that contains scene data, including prims, layers, and composition information. The root container for USD scene content.
Component	A self-contained USD asset representing an individual part or functional unit that can be reused and composed into larger assemblies.
Assembly	A USD structure that aggregates multiple components or other assemblies using composition arcs to create larger, more complex scenes.
Composition Arc	A USD mechanism that defines how multiple layers or references are combined, including references, payloads, inherits, specializes, and variants.
Layer	A USD file that contains specific data or opinions about scene elements, which can be composed with other layers to build complex scenes.
Reference	A composition arc that brings content from another USD file into the current stage, creating a live link to the source data.
Payload	A composition arc that loads content from another USD file on-demand, improving performance by deferring loading until needed.
Variant	A USD feature that allows different versions of the same asset to be stored in a single file, with the ability to switch between variants at runtime.
Attribute	A named data field attached to a prim that stores values like transforms, geometry data, material assignments, or custom properties.
Schema	A USD class definition that specifies the structure, attributes, and behavior of a prim type, ensuring consistency across assets.
Sublayer	A composition arc that combines multiple USD layers into a single stage, allowing data from different sources to be merged together.
Material Binding	A USD mechanism that associates materials with geometry prims, allowing for proper rendering and material inheritance through the scene hierarchy.
Geometry	A USD prim type that represents 3D shapes, including meshes, curves, points, and other geometric data that can be rendered or processed.
Scope	A USD prim type that serves as a container for organizing other prims in the scene hierarchy, providing structure without adding visual content.
Xform	A USD prim type that represents a transform node, containing transformation data and serving as a parent for other prims in the hierarchy.
Looks	A USD prim type that contains material and shading information, typically organized under a scope to manage appearance data separately from geometry.
Metadata	Additional information stored with USD files, including author information, creation dates, units, up-axis, and other scene-level properties.
Time Code	A USD metadata field that specifies the time format and range for animated content, supporting frame-based and time-based animation systems.
Up Axis	A USD metadata field that defines the coordinate system orientation (Y-up or Z-up), ensuring consistent scene interpretation across different applications.
Meters Per Unit	A USD metadata field that specifies the scale of the scene, defining how many meters each unit represents for accurate real-world measurements.
Atomic Asset	A self-contained USD component that encapsulates all necessary data (geometry, materials, transforms) in a single, portable file that can be easily shared and reused.

RTX Rendering

The following glossary provides concise explanations of key terms related to RTX Rendering, focusing on how acceleration structures like BLAS and TLAS optimize ray tracing performance in 3D scenes.

Name	Description
Bottom Level Acceleration Structure (BLAS)	• Ray tracing involves shooting rays into a 3D scene to determine what they hit (for lighting, shadows, reflections, etc.). • To make this efficient, the scene’s geometry is organized into special data structures called acceleration structures. • BLAS is the acceleration structure built for individual meshes or objects in the scene. • It typically uses a Bounding Volume Hierarchy (BVH), which is a tree of bounding boxes that quickly cull away geometry that a ray cannot possibly hit.
Top Level Acceleration Structure (TLAS)	• TLAS organizes the entire scene for ray tracing. • It is built on top of BLASes (Bottom Level Acceleration Structures), which represent individual meshes or objects. • The TLAS contains instances of BLASes, each with its own transformation (position, rotation, scale). Why is it important? • Efficiency: Instead of checking every triangle in the scene, the TLAS lets the renderer quickly skip over large parts of the scene that the ray can’t possibly hit. • Instancing: The same mesh (BLAS) can be reused in many places with different transforms, saving memory and build time. • Dynamic Scenes: TLAS can be rebuilt or updated quickly if objects move, while BLASes only need to be rebuilt if the mesh itself changes.