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For other meanings, see ACIS (disambiguation)

In Ovid's Metamorphoses, Acis (Greek: Άκις) was the spirit of the Acis River in Sicily,[1] beloved of the nereid, or sea-nymph,[2] Galatea (Γαλάτεια; "she who is milk-white"). Galatea returned the love of Acis, but a jealous suitor, the Sicilian Cyclops Polyphemus,[3] killed him with a boulder. Distraught, Galatea then turned his blood into the river Acis. The Acis River flowed past Akion (Acium) near Mount Etna in Sicily.

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Acis and Galatea by Claude Lorrain

According to Ovid's Metamorphoses, Acis was the son of Faunus and the river-nymph Symaethis, daughter of the River Symaethus.

The tale occurs nowhere earlier than in Ovid; it may be a fiction invented by Ovid "suggested by the manner in which the little river springs forth from under a rock".[4] According to Athenaeus, ca 200 BCE[5] the story was first concocted as a political satire against the Sicilian tyrant Dionysius I of Syracuse, whose favourite concubine, Galatea, shared her name with a nereid mentioned by Homer. Others[6] claim the story was invented to explain the presence of a shrine dedicated to Galatea on Mount Etna.

A first-century fresco removed from an Imperial villa at Boscotrecase, preserved by the eruption of Vesuvius, and now at the Metropolitan Museum of Art[7] shows the three figures as incidents in a landscape.

Polyphemus Surprising Acis and Galatea, by Auguste Ottin (1866), the Fontaine Médicis, Jardin du Luxembourg, Paris

Cultural references

The tale of Acis and Galatea was familiar from the Renaissance onwards: there are paintings of the subject, sometimes as mythological incidents in a large landscape, by Adam Elsheimer.[8] Nicolas Poussin (National Gallery of Ireland), and Claude Lorrain (Dresden).[9]

In music, the story was the basis for Lully's Acis et Galatée. Handel created both Acis and Galatea and Aci, Galatea e Polifemo on the story and Antonio de Literes wrote the zarzuela Acis y Galatea. Jean Cras's opera Polyphème is also based on the story.

Claude Lorrain's painting of Acis and Galatea inspired Fyodor Dostoevsky's description of the 'Golden Age'; explicitly in 'A Raw Youth' and in Stavrogin's dream in 'The Devils', and implicitly in 'The Dream of a Ridiculous Man'.

Notes

  1. ^ Ovid. Metamorphoses xiii. 750–68.
  2. ^ Hesiod. Theogony; Homer. Iliad.
  3. ^ Philoxenus of Cythera, Theocritus Idylls VI; Ovid Metamorphoses xiii.750-68.
  4. ^ Schmitz, Leonhard (1867), "Acis", in Smith, William, Dictionary of Greek and Roman Biography and Mythology, 1, Boston, MA, pp. 13, http://www.ancientlibrary.com/smith-bio/0022.html  
  5. ^ Athenaeus, Deipnosophistae 1.6e
  6. ^ Scholiast on Theocritus' Idyll VI quoting the historian Duris and the poet Philoxenus of Cythera
  7. ^ Polyphemus and Galatea in a landscape
  8. ^ National Gallery of Scotland. Elsheimer changed his mind midway and painted out the figures, rendering the painting a pure landscape. Elsheimer highlights
  9. ^ Other images of Acis, Galatea and Polyphemus are displayed at the ICONOS site.

References

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3D ACIS Modeler
Developer(s) Spatial Corporation
Stable release Version R19 / July 2008
Operating system Windows 2000 (and above), AIX (IBM), Solaris (Sun Microsystems), HP-UX (Hewlett-Packard), Mac OS X (Apple Computer) and Linux (Red Hat)
Type 3D modeler
License Proprietary software
Website www.spatial.com

The 3D ACIS Modeler (ACIS) is a 3D modelling kernel (or engine) owned by Spatial Corporation (formerly Spatial Technology). ACIS is used by many software developers industries such as computer-aided design, (CAD), Computer-aided manufacturing (CAM), Computer-aided engineering (CAE), Architecture, engineering and construction (AEC), Coordinate-measuring machine (CMM), 3D animation, and shipbuilding. ACIS provides software developers and manufacturers the underlying 3D modeling functionality.

ACIS features an open, object-oriented C++ architecture that enables robust, 3D modelling capabilities. ACIS is used to construct applications with hybrid modeling features, since it integrates wireframe model, surface, and solid modeling functionality with both manifold and non-manifold topology, and a rich set of geometric operations.

ACIS can also be used for a 3D CAD file formatting that will allow you to do a FEM on a MRI image.

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History

As a geometric kernel, ACIS is second generation system, coming after the first generation Romulus [1]

There are several versions about what the word ACIS actually stands for, or whether it is an acronym at all. The most popular version is that ACIS stands for Alan, Charles, Ian's System (Alan Grayer, Charles Lang and Ian Braid as part of Three-Space Ltd.), or Alan, Charles, Ian and Spatial (as the system was later on sold to Spatial Technology, now Spatial Corp). However, when asked, the creators of ACIS would simply suggest that its name was derived from Greek mythology (See also Acis).

In 1985 Charles Lang and Ian Braid (creators of Romulus and Romulus-D) formed Three-Space Ltd. (Cambridge, England) which had been retained by Dick Sowar's Spatial Technology (which had ben founded by Sowar in 1986) to develop the ACIS solid modeling kernel for Spatial Technology's Strata CAM software. The first version of ACIS was released in 1989 and was quickly licensed by HP for integration into its ME CAD software.

In late 2000, around the time when Spatial was acquired out by Dassault Systemes, the ACIS file format changed slightly and was no longer openly published.

Architecture

A software component is a functionally specialized unit of software—a collection of software items (functions, classes, etc.) grouped together to serve some distinct purpose. It serves as a constituent part of a whole software system or product. A product is one or more software components that are assembled together and sold as a package. Components can be arranged in different combinations to form different products.

The ACIS product line is designed using software component technology, which allows an application to use only the components it requires. In some cases, more than one component is available (either from Spatial or third party vendors) for a given purpose, so application developers can use the component that best meets their needs. For example, several rendering components are available from Spatial, and developers use the one that works best for their platform or application.

Supported Platforms and Operating Systems

Platform Operating System Compiler 32-bit 64-bit
Microsoft Windows XP Professional SP2 Visual C++ .NET 2005 X X
Microsoft Windows 2000 SP4 Visual C++ .NET 2003 X
Microsoft Windows XP Professional x64 Edition Platform SDK for Windows Server February 2003 Version 13.10.2240.8 X
Red Hat Enterprise Linux, Version 5 GNU C++ gcc 4.1.2 X X
Apple OS X 10.4 (Native BSD) GNU C++ gcc 4.0 and XCode 2.3 X
IBM AIX Version 5.3 VisualAge C++ Version 8.0 X X
HP HP-UX 11i v1 HP aC++ Version A.03.52 X X
SunTM SolarisTM 10 Sun ONETM Studio 10 X X

Functionality

ACIS Modeler

ACIS core functionality[2] can be subclassified into three categories, namely:

3D Modelling

  • 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.

3D Model Management

  • 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.

3D Model Visualization

  • 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

ACIS Modeler Extensions

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.
3D PHL V5
3D ACIS PHL V5 is a hidden line removal (HLR) solution from Spatial based on CATIA V5 technology. 3D ACIS PHL V5 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.

File format

ACIS saves modeling information to external files which have an open format allowing external applications, even those not based on ACIS, access to the ACIS geometric model. The basic information needed to understand the ACIS file format (focusing on the reading, or restore, operation), includes the structure of the save file format, how data is encapsulated, the types of data written, and subtypes and references.

Save File Types

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.

Structure of the Save File

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.

Version Numbers and ACIS Releases

ACIS is currently being developed by Spatial. They maintain the concept of a current version (release) number in ACIS, as well as a save version number. The save version allows one to create a SAT save file that can be read by a previous version of ACIS.

Beginning with ACIS Release 4.0, the SAT save file format does not change with minor releases, only with major releases. This allows applications that are based upon the same major version of ACIS to exchange data without being concerned about the save version. To provide this interoperability in a simple implementation, ACIS save files have contained a symbol that accurately identified the major version number, but not the minor version. This meant that applications created using the same major version of ACIS would produce compatible save files, regardless of their minor versions. This was accomplished by simply not incrementing the internal minor version number between major versions.

Beginning with Release 7.0, ACIS started again providing accurate major, minor, and point version numbers.

To summarize how release numbers and SAT changes are related:

  • Major release: SAT file changes may be made; significant functionality changes likely; may require significant changes to existing applications
  • Minor release: No SAT file changes are made; may provide new functionality; may require some minimal changes to existing applications
  • Point release: Minor changes only (bug fixes). (Also known as service packs).
Release Date
19.0 July 2008
18.0 November 2007
17.0 April 2007
16.0 January 2006

See also

References

External links

This article was originally based on material from the Free On-line Dictionary of Computing, which is licensed under the GFDL.


1911 encyclopedia

Up to date as of January 14, 2010

From LoveToKnow 1911

ACIS, in Greek mythology, the son of Pan (Faunus) and the nymph Symaethis, a beautiful shepherd of Sicily, was the lover of the Nereid Galatea. His rival the Cyclops Polyphemus surprised them together, and crushed him to pieces with a rock. His blood, gushing forth from beneath, was metamorphosed by Galatea into the river bearing his name (now Fiume di Jaci), which was celebrated for the coldness of its waters (Ovid, 750; Silius Italicus, Punica, xiv. 221).


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Wikispecies

Up to date as of January 23, 2010

From Wikispecies

Acis may mean:



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