The 3D ACIS® Modeler (ACIS) is Spatial’s prominent 3D solid modeling engine. 3D InterOp is a CAD data translation framework (Interoperability)

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This alphabetized and hyperlinked glossary explains the terms used in 3D InterOp Connect documentation. The glossary will be updated over time.

ACIS Modeler

ACIS 3D Geometric Modeler (ACIS) is an object-oriented geometric modeler, composed of libraries of C++ classes and functions, on top of which 3D modeling applications are built. ACIS consists of a variety of components that provide core modeling and other specialized support functionality.

Acorn Bodies

One or more zero-dimensional point bodies in space. An acorn body contains only one type of geometry, points that are attached to the vertices in the body. A single point Acorn Body contains one (void) region, one shell, one loop, and one vertex.

Analytic curves

An analytic curve represents a simple curve that can be represented analytically by an equation.

Analytic surfaces

An analytic surface represents a simple surface that can be represented analytically by an equation.

Annotation

Annotation is extra information/Text associated with a particular topological or geometrical entity.

AP203 format

International standard for STEP format which defines the geometry, topology, and configuration management data of solid models for mechanical parts and assemblies.

AP214 format

International standard for STEP format since 2001 which defines 2D/3D wireframe representation, geometrically/topologically bounded surface representation, faceted boundary representation, Boundary representation, compound solid representation, and compound solid geometry representation.

API

The Application Procedural Interface (API) is a set of functions that provide functionality.

Application License Key

An application license key (also referred as license key) comprises of a key string and a license-specific function provided in a C++ file from the Spatial Licensing Web site. This key is used for authentication purposes.

Assembly

An assembly is a collection of instances of parts (parts are bodies or assemblies). An Assembly allows you to create different instances of the same part with different transformation instead of creating its different copies at different locations.

Attributes

It is the data of particular types that can be attached to an entity or group entity.

BASIC dimension

The theoretical value for describing the exact size or location of a feature.

Body

A body is a collection of lumps that have a common transform.

• A wire body contains no faces, shells, or lumps.

• A sheet body is an infinitely thin body, with faces that do not completely enclose a volume.

• A solid body completely encloses a volume.

Boundary Representation Modeler

A modeler for solid modelling.

B-spline

A geometric entity whose shape is governed by control points.

C1 continuity

First order geometric continuity. If continuous at the point of connection, tangents will have the same direction and magnitude.

C1 continuous edges

Edges which are C1 continuous.

Callback

It is a mechanism to track the translation at run time.

Canonical form

A differential form of an object defined in a natural (canonical) way.

Coedges

A coedge records the occurrence of an edge in a loop of a face. The introduction of a coedge permits edges to occur in one, two, or more faces. Coedges make the modeling of sheets and solids, both manifold and non-manifold, possible.

Component

Component is a combination of several shared libraries

Copious Data

An IGES entity that stores data points in the form of pairs, triples, or sextuples. Its entity number is 106.

Curve

A curve is a mathematical representation of a 3D curve, used in place of an edge when high computational efficiency is required. Curves hold count of the number of edges that refer to a curve and provides information on individual curve types (straight lines, ellipses, circles, and spline curves).

Datum

A theoretically exact point, axis, or plane derived from the true geometric counterpart of a specified datum feature. A datum is the origin from which the location or geometric characteristics of features of a part are established.

Datum targets

A specified point, line, or area on a part used to establish a datum.

DITTO

DITTO is an instance of the detail workspace to which it refers. It is treated as a assembly.

DLL

Dynamically Linked Library (DLL) is a library of functions that are loaded in memory at run time.

Document

A document is essentially a CAD data container.

Driven Type dimension

Dimensions used for information.

Edge

A topology representing a bounded piece of a single curve. Edges reference their face, curve, fins, and bounding vertices.

Entity

An entity is the most basic model element that can be saved and restored. All entities have a common set of functionality, such as the ability to save and restore to/from a file, copy, and debug. Entities are implemented in the class ENTITY. All other geometric and higher level ACIS objects are derived from ENTITY.

Entity list

A class which is a collection of ACIS entities.

Face

A face is a surface bounded by edges. One or more loops of edges bound a face. A face can bound a solid region, be embedded in a solid region, or only represent a 2D region. A face can be double-sided (infinitely thin). It can also be single-sided, the face normal points away from one side of the face and solid material is present on the other side of the face. A single-sided face is a solid body, not a sheet body.

Face limits

A box defined by u and v parameter of a face.

face-face inconsistencies

Inconsistency that appears when two more faces of same body intersect with each other.

Facet

A facet, also known as tessellation, is a polygon. Facets are used to break down a surface into an approximate representation.

Free curves

Free curves is a geometric entity, which is not attached to any edge or coedge of a model.

Free face

Free face is a fundamental item of topology that does not reference a shell.

Free point data

A geometric entity which is not attached to a vertex.

Free surface data

A geometric entity which is attached to a face. It is also attached as construction geometry.

Free surfaces

A geometric entity which is attached to a face. It is also attached as construction geometry.

G1 continuity

First order geometric continuity. If continuos at the point of connection, tangents will have the same direction.

Geometric Dimensioning and Tolerancing

Geometric dimensioning and tolerancing is a symbolic language used on engineering drawings and computer-generated, three-dimensional solid models (CAD) for explicitly describing nominal geometry and its allowable variation.

Geometric Tolerance

Specifies allowable variation in the form of a geometry.

Group entities

Collection of geometric or topology entities.

Healing

Identifying and fixing invalid or incorrect models imported from other modeling systems into ACIS in order to make them usable in ACIS.

IGES 144 or 143 trim surfaces

IGES Type 143 represents Bounded Surface Entity and IGES Type 144 represents Trimmed (Parametric) Surface Entity. Both are used to represent trimmed surfaces.

IGES entity of type 106

IGES Type 106 represents Copious Data Entity, and stores data points in the form of pairs, triples, or sextuples.

Inheritance

Inheritance is the process by which a derived, child C++ class can use the methods and data definitions of its parent class.

Inspection type

A type of Pro/E specific dimension, similar to Reference type dimension.

Instantiation

Instantiation is the process of creating an instance (that can hold data) from a C++ class.

Iso-parameter lines

Line at constant parameter on a given surface.

kernel

Alternative name for a library.

Layer filters

A collection of layer entities to specify common properties.

Linear BASIC dimension

Basic Dimension used to measure or represent the linear distance.

Linear Driven dimension

Dimension used to represent linear distance.

Local Coordinate System

A working coordinate system in model space.

Lumps

A lump represents a connected 3D (solid) and/or 2D (sheet) region. A body can contain zero or more lumps. Each lump represents a disjoint set of points. One lump can be completely enclosed inside the void of another solid lump. Each lump must have at least one shell.

Manifold

It is an abstract mathematical space in which every point has a neighborhood which resembles Euclidean space.

Manifold Solid B-Rep Object

Solid bodies which could exist in real terms.

Manifold Solid B-Rep Object (MSBO)

A MSBO is a bounded, closed, and a finite volume Body in three dimensional Euclidean space. It has an exact boundary representation and defines a manifold solid by enumerating its boundary.

Memory leak

Condition where allocated memory is not released.

Mesh

Mesh represents a network of planar polygonal elements for modeling large scale surfaces. MESH allows efficient representation of grid data sets and large scale surfaces of the type associated with prototyping, geoscience surface modeling, and animation, without the overhead involved in solid modeling topology.

Mesh data

Mesh data is a collection of triangles that define a shape within the model.

Modeler

A modeler is a tool to build and manipulate Solid objects.

Multi-lump solids

A solid body having multiple lumps.

Multi-lumped body

A body having multiple lumps.

Mockup solids

Mockup are tessellated solids without exact representation for surfaces.

NUBS

Non-Uniform B-spline is a spline defined with respect to B-spline basis functions. The coefficients assigned to these basis functions are termed control points. It may be:

• Fully rational: Each control point has associated with it a weight.

• Purely polynomial: The control point has no weight associated.

• Non-uniform: The values in the knot vector are not necessarily uniformly spaced and may even be coincident.

NURBS

Non-Uniform Rational B-splines are a way of representing curves and surfaces.

Option

A string used to specify behavior during the translation process.

Part

A group of entities that can be manipulated as a single item.

Pcurves

Parametric space curves, 2D curve.

Periodic faces

The faces which are periodic in nature.

Planar sheet bodies

Sheet bodies with face geometries of plane type.

PMI

Product and Manufacturing Information (PMI) is the information attached to the design of a product components for manufacturing.

PolyLines

A set of connected straight lines.

Preprocessor

A program that processes its input data to produce output that is used as input to another program.

Preprocessor directives

A directives for preprocessor which are not program statements, always preceded by # symbol.

PSET data

PSET is a sequence of multiple number of coordinate points.

Reference Angular dimension

Reference type dimension used to represent angle value.

Representation

InterOp defines various representations for handling various data types during translation.

RFS

Regardless of Feature Size (RFS) is a term used to indicate that a geometric tolerance or datum reference applies at any increment of size of the feature within its size tolerance.

Roughness

A measurement of the small-scale variations in the height of a physical surface.

Runtime libraries

A collection of utility functions which support a program at runtime.

SAT File

ACIS saves or stores, model information to ACIS save files (also known as part save files or part files). ACIS also restores model information from these files. These files have an open format so that applications not based on ACIS can have access to the ACIS model. There are two types of ACIS save files: text (file extension .sat, which stands for Standard ACIS Text) and binary (file extension .sab, which stands for Standard ACIS Binary). The only difference between these files is that the data is stored as ASCII text in a .sat file and in binary form in a .sab file. The organization of a .sat file and a .sab file is identical. The term SAT file is generally used to refer to both.

Scene Graph based visualization

A general data structure commonly used by vector-based graphics, editing applications, and modern computer games.

Selection sets

A group of selected entities.

Sheet bodies

A sheet body is an infinitely thin body that has at least one face, but does not enclose a solid area. Generally the faces are double-sided, indicating that they are infinitely thin with no material on either side.

Solid body

A solid body totally encloses a volume. A solid body has no dangling faces or dangling edges. A single-sided face is a solid body, not a sheet body. If a solid body, such as a cube, is missing a face, the body is said to be unbounded (infinitely long) in that direction.

Splines

Spline refers to a curve or surface that cannot be directly represented by one of the simple analytic surfaces. They are indirectly represented by an ordered list of analytic formulae by segmenting the curve or surface with control points.

Stitching

A process where a collection of sheet bodies can be sewn together by gluing them where their edges meet, resulting in a single connected body.

Sweep surfaces

A surface generated by sweeping a given curve in a given direction.

Tessellate

To cover or divide into identical shaped pieces that do not overlap.

Topology

Topology is the set of spatial relationships between the various geometric entities, recorded in a classes body, wire, lump, shell, subshell, face, loop, coedge, edge, and vertex.

U parameter lines

Parameter lines in U direction of a surface

Unbounded plane

A plane which does not have a boundary or trimming curves.

Unicode

It is an industry standard which is designed to allow text and symbols from all of the writing systems of the world to be consistently represented and manipulated by computers.

Vertex

A vertex is the corner of either a face or a wire. A vertex refers to a point in object space and to the edges that it binds.

Visualization

A representation defined by to handle visualization data.

Visualization shells

Shells consisting of visualization data.

Void

A void in geometry refers to an enclosed hollow region within a solid. For example, if a small sphere is subtracted from the center of a larger sphere, the resulting hollow region is called a void.

V parameter lines

Parameter lines in V direction of a surface.

Wire

A wire is a collection of edges and vertices that typically represent profiles, construction lines, and center lines of swept shapes. Wires can also represent wireframes that, when surfaced, form shells.

Wire body

A wire body contains no faces, shells, or lumps. The minimal case of a wire body consists of a wire record, coedge, and edge with null geometry whose start and end are a single vertex with a point.

Work Coordinate System

A Work Coordinate System (WCS) is a plane specified in relation to model space in which all entity creation and modification operations take place.

Workplane

A defined plane in model space.