ACIS

ACIS core functionality[4] can be subclassified into three categories, namely:

• Extrude/revolve/sweep sets of 2D curves into complex surfaces or solids.
• Fillet and chamfer between faces and along edges in surface and solid models.
• Fit surfaces to a closed network of curves.
• Generate patterns of repetitive shapes.
• Hollow solids and thicken surfaces.
• Interactively bend, twist, stretch, and warp combinations of curves, surfaces, and solids.
• Intersect/subtract/unite any combination of curves, surfaces, and solids.
• Loft surfaces to fit a set of profile curves.
• Taper/offset/move surfaces in a model.

• Attach user-defined data to any level of a model.
• Track geometry and topology changes.
• Calculate mass and volume.
• Model sub-regions of a solid using cellular topology.
• Unlimited undo/redo with independent history streams.

• Tessellate surface geometry into polygonal mesh representation.
• Create advanced surfacing capabilities with the optional Deformable Modeling component.
• Generate precise 2D projections with hidden line removal using optional PHL V5 component.
• Develop graphical applications

CGM Polyhedra

CGM Polyhedra is an add-on to the 3D ACIS Modeler combining polyhedral and B-rep modeling. Utilizing the same interfaces that 3D ACIS Modeler users are already familiar with, existing and new customers can integrate approximated polyhedral data to their 3D printing, subtractive manufacturing, analysis, and other workflows.

3D Deformable Modeling

3D Deformable Modeling is an interactive sculpting tool for shaping 3D models. Included as part of Spatial's suite of 3D modeling development technologies, 3D Deformable Modeling uses local and global editing features that allow for the easy creation and manipulation of free-form B-spline and NURBS curves and surfaces.

Advanced Covering

Advanced Covering is a feature of Deformable Modeling that is now available as a standalone add-on for the 3D ACIS Modeler. This single API uses sophisticated algorithms to create high-quality n-sided surfaces that meet user-specified tolerances for position and continuity on boundaries and on optional internal guiding geometry. Advanced Covering allows a surface to be fit onto circuits (collections of edges that form closed loops) in solid or wire bodies, which is useful in consumer product design. Among other uses, Advanced Covering can be used for end-capping, post-translation corrections, and surface definition from curve data.

Defeaturing

Defeaturing automatically identifies and removes small features that CAE analysts typically want to eliminate from the 3D model prior to meshing. Analysts frequently work from the same models that are used for design and manufacture, but these models often carry much more detail than is necessary for simulation or analysis purposes. By removing unnecessary detail, Defeaturing simplifies the model, a process that typically is done manually at significant cost.

CGM HLR

CGM HLR is a hidden line removal (HLR) solution from Spatial based on CATIA V6 technology. CGM HLR is an ACIS-dependent development technology - an ACIS license is required. Though 3D is now the de facto CAD standard in most engineering disciplines, 2D still has a place in industries such as technical illustration, manufacturing, and architecture. Since 3D models are the typical primary output for CAD design, users in these industries require an efficient and accurate method of generating 2D computational drawings directly from the 3D models. Hidden line removal (HLR) is an important aspect of creating an accurate 2D representation from a 3D model. Using HLR, the converted model only displays those parts visible from a given perspective; hidden (or occluded) edges normally included in a 3D model representation are removed, or drawn in a line style that indicates their obscured position.

ACIS supports two kinds of save files, Standard ACIS Text (SAT), and Standard ACIS Binary (SAB). The two formats store identical information, so the term SAT file is generally used to refer to either when no distinction is needed.

SAT files are ASCII text files that may be viewed with a simple text editor. A SAT file contains carriage returns, white space and other formatting that makes it readable to the human eye. A SAT file has a .sat file extension.

SAB files cannot be viewed with a simple text editor and are meant for compactness and not for human readability. A SAB file has a .sab file extension. A SAB file uses delimiters between elements and binary tags, without additional formatting.

Specification of SAT format for version 7.0 (circa 2001) has been made publicly available. This allowed external applications, even those not based on ACIS, accessing the data stored in such files. The basic information needed to understand the SAT file format, such as the structure of the save file format, how the data is encapsulated, the types of data written, subtypes and references, is available from this document. However the newer version of ACIS use modified format of SAT files whose specification is not publicly available. Thus reading of modern SAT files requires either using native ACIS library or reverse engineering of the format.

A save file contains:

• a three-line header
• entity records, representing the bulk of the data
• optionally, a begin history data marker
• optionally, old entity records needed for history and rollback
• optionally, an end history data marker
• an end marker

Beginning with ACIS Release 6.3, it is required that the product ID and units be populated for the file header before you can save a SAT file.