Entities in Creo
Entities are model elements that you can select. These include geometric entities, reference entities, and non-geometric items used for modeling, documentation, and simulation. Following are some of the entities you work with when you create and edit models in Creo.
Entity
Any object in the model that can be selected and operated on.
In Creo, entities are the fundamental geometric elements of a model, such as surfaces, edges, and vertices. They can be sketched, feature-generated, or derived from existing geometry. They are used to create features, define relationships, apply dimensions, and serve as references for modeling and simulation.
Annotation
Non-geometric elements for adding the product and manufacturing information to the model, and for documentation and communication purposes. Examples include:
• Dimensions
• Text notes
• Symbols
• GD&T (Geometric Dimensioning and Tolerancing) information
Type: User-defined information
Body
A body represents a portion of solid material. It has three-dimensional geometry that represents the volume claimed by the material, and also a set of attributes that represents the material definitions and other properties. A part can contain one or more bodies.
Type: Derived geometry, user-defined attributes
Curve
A curve is a one-dimensional geometric entity that is used to define shapes, paths, or references. A curve can be a line, but it does not have to be straight, so it can form an arc, or a 3D spline like a helix. A curve can lie in a plane or in three-dimensional space (a 3D curve).
Type:
• Often user-defined (for example, sketch curves and datum curves)
• Sometimes derived (for example, intersection curves)
Datum
Auxiliary entities for defining other geometric features, used as references for position, orientation, or measurement. The common datum entities are:
• Coordinate system
• Datum plane
• Datum axis
• Datum point
Type: User-defined reference entities
Edge
One-dimensional geometric entity that forms the boundary of a surface. Edges can be straight or curved. There is a vertex at the junction between two edges. They can also represent an intersection curve between surfaces.
Type: Derived (resulting) geometry. Edges are created automatically when features generate surfaces or when surfaces intersect.
Feature
The fundamental building block of the CAD model. A feature represents the instructions for creating or modifying geometry or information. Examples include:
• Extrude
• Hole
• Round
• Pattern
• Measure
• Annotation
Part
Complete 3D model representing a single component or object. A part can contain:
• Features
• Solid bodies
• Geometry (surfaces, edges, vertices)
• Datums
• Annotation
Type: Top-level modeling object
Quilt
Collection of connected zero-thickness surfaces that form a continuous sheet.
Quilts are commonly used in surface modeling and can be used as tools for creating or modifying solid geometry.
Type: Derived geometry created from surfaces
Region
Bounded area defined by closed edges or curves.
Regions are widely used in simulation and analysis for defining loads, constraints, and boundary conditions. Sketch Regions are used as input for sketch-based features. Surface regions are used as input for Creo Flexible Modeling operations.
Type: Often derived, sometimes user-defined
Surface
Two-dimensional geometric entity that can be used as the boundary of a physical object. A surface can belong to a solid body where it represents the outermost layer of the solid material, or it can belong to a quilt, which is a collection of zero-thickness surfaces.
Type: Usually feature-generated (derived) geometry
Vertex
Precise geometric point that represents the endpoint of at least one edge in a model.
Type: Derived (resulting) geometry. Vertices are created automatically as a result of edges and cannot normally be defined directly as part of solid geometry.