The ACIS format is a text based solid modelling format that has been heavily used by Autodeck products but is also used by the Tribon/Aveva Marine Initial Design tools which unfortunetly does not yet support the more commonly used IGES formats. As with most solid modellers, the process of importing geometry and trying to get the modeller to accept the data can often be difficult because of definition and tolerance issues.
Exporting Valid Solid Bodies
Solid modellers work with complex entities defined by collections of vertices, curves and surfaces. Consequently, to export the raw geometry contained within PolyCAD this additional information must be automatically generated. For individual curves and surfaces this is a straight forward process. However, for complicated models particularly hull surfaces defined by a number of patches, the process of automatically generating the solid assembly of patches is non-trivial. PolyCAD will attempt to match the corners and edges to form a valid solid body. At present, PolyCAD does not try to resolve internal surface discontinuities which may cause solid modelling operations to fail or modelling errors which may prevent the solid model topology from being generated. If a problem is encountered during the formation of the solid, PolyCAD will endevour to save the surfaces as individual bodies. As PolyCAD is trying to something fairly complicated without human assistance the chance of an error occuring is quite high. If you encounter any with exporting a geometry to ACIS then please feel free to submit the file for investigation.
Importing Solid Body Geometry
PolyCAD does not support generic Solid Models stored in ACIS files but can be used to strip out any raw curve and surface definitions stored within an ACIS file.
Supported ACIS Versions
PolyCAD supports the import of data from ACIS files up to version 11, later versions have not been tested. PolyCAD exports ACIS data in version 4.0 format because less information is required compared to later developments.
|BSpline Surface||Yes (See below)||Yes (See Exporting Valid Solid bodies above)|
|BSpline Suface List||Yes (Grouped by Body)||Yes|
|Cubic Spline||as Polyline|
|Interpolating Cubic BSpline||Yes|
|X-Topology Curves||as BSpline|
|X-Topology Surface||Transferred as a complete body if represented by BSpline surfaces.|