Data Transfer Notes

The following information is new for Version 9.0:

• New Limitations on page 53

The following information exists from previous releases:

• Existing Limitations on page 53

• External Applications Window on page 57

• Pre-Version 3.2 Wire File Format on page 57

• Exporting Geometry to the SLC File Format on page 58

New Limitations

Limitation

AliasBatch -o /usr/tmp/.Alias/Prefs.2/Options/opt  
-s foo  /usr/tmp/V9o.wire




Scheme error in file 'stdin' on line '1'




Error symbol: ui-load




Error in file '/usr/tmp/.Alias/Prefs.2/Options/opt' 
on line '5118' 




unbound variable: ~s : ui-function-symbol-list

These can errors can safely be ignored.

Workaround

Existing Limitations

Limitation

IGES 5.3 allows the creation of IGES files that are year 2000 compliant. The default option is 5.3, but some receiving systems may not be able to handle the extra data in the date field and thus cannot yet support the 5.3 format.

Limitation

CATIA model files that were built in millimeters will not have this problem in any version of CATIA and CAI files exported from CATIA 4.1.9 Refresh 1 will not have this problem.

Workaround

Limitation

Workaround

Therefore, any ASCII STL file that was created with output units other than cm must be scaled appropriately once the file is read in. See the person who created the STL file to determine what the original units were so that you can set the scaling factor accordingly.

For example, if the STL file units are in mm, then after importing the file, the geometry must be scaled by 0.1.

Limitation

Limitation

Alias spline trim curves are rational b-splines. The IGES Parametric Spline Curve and Surface entities (types 112 and 114, respectively) do not support rational B-splines directly. In order to represent Alias trim curves using these IGES entities, the trim curves are automatically rebuilt to remove the rational component.

This rebuild operation is the extra step that takes time. This operation is not necessary when the Spline Type is set to B-SPLINE , since the IGES Rational B-Spline Curve entity (type 126) fully supports Alias trim curves.

Limitation

With default display settings, surfaces of degrees higher than 13 appear distorted when input into Alias.

Workaround

Limitation

If an object is created in SGI Showcase and stored in EPS format, it is not possible to retrieve the object into Alias with the retrieve option for EPS. Alias gives an error message in the prompt line saying than an I/O error has occurred and that the retrieve has been aborted.

Limitation

Workaround

Limitation

Some objects written by Sketch! 1.5 and Sketch! 2.0 in StyleGuide Export format are not read correctly by the StyleGuide input translator. Specifically, curves on surfaces and certain types of square faces. The curves on surface are likely to move so that they are no longer on their surface and may be distorted.

Workaround

Limitation

Workaround

Limitation

All pivots in StyleGuide files are set to 0,0,0, in Alias 9.0, regardless of their position in Sketch!

Limitation

Surfaces are rendered "double-sided" by default in Alias, so during creation the direction of the surface normals are not evident unless explicitly checked. 3Design renders "single-sided" by default, and hence, surfaces brought from Studio that have accidentally been created "back-to-front" will appear dark.

Workaround

Limitation

Sometimes, trimmed surfaces imported via Geo files do not render properly.

Workaround

External Applications Window

The Input File and Output File filenames of the File->External Applications Window may be specified as either absolute UNIX path names (the full path name location of the file), or as filenames with no path. If there is no path, the file is assumed to be in the "wire" directory of the current project.

There must be no partial input file or output file name specifications in the application name. For example, the program my-prog below takes two arguments; the input file followed by the output file.

The following shows the incorrect and correct ways to specify the execution of this program in the Application Name field:

Incorrect:

/usr/u/yourid/bin/my-prog /usr/u/aldemo/data/%i /
usr/u/aldemo/data/%o

Correct:

/usr/u/yourid/bin/my-prog %i %o

where the input file name is specified as /usr/u/aldemo/data/infile and the output file name is specified as /usr/u/aldemo/data/outfile .

Also, all settings in the External Applications Window are saved from session to session on a per Application Name basis.

Pre-Version 3.2 Wire File Format

The WireConvert standalone utility that converts pre-Version 3.2 wire files to Version 3.2.1 wire format has not been shipped since Version 8.0 when it was located in the bin.obsolete directory. The WireConvert utility was no longer supported as of Version 7.

If you have kept this utility from a previous Alias installation, note that IRIX 5.3 is the last version of the OS that is able to run this utility.

Exporting Geometry to the SLC File Format

The Save SLC command creates a file in the .slc format. This format differs from the .stl format largely in that the NURBS geometry is sliced to a resolution at which the part will eventually be built. As a result, there is only one abstraction of the original NURBS geometry. It also means that you have an increased responsibility to confirm the integrity of the NURBS geometry in Alias before creating the .slc file.

Stitching

The process that creates the slc file intersects a plane with the model and creates a polyline where the plane intersects the first NURBS surface. For this reason, before the calculation is carried out, the NURBS surfaces must be stitched together with Shell->Stitch so it can be read as one piece of geometry.

A by-product of stitching the surface geometry is that you can see surface boundaries with gaps that would cause problems when the slicing operation takes place. If the stitching operation identifies surface boundaries that are not within a tolerance acceptable to the stitching code, the gaps would also be recognized as a gap large enough to produce broken polylines and therefore unusable in the building of the part.

Surface boundaries that do not stitch together must be recreated with a lower Curve Fit tolerance. A good workflow is to create a small and representative part of the model first and test-stitch it to ensure the chosen tolerances before a lot of time is spent modeling. The stitching process uses the tolerance in calculating whether or not surfaces have the necessary conditions to stitch together.

When geometry is stitched unsuccessfully (that is, you can see interior surface boundaries that did not stitch together) you can use the key command Ctrl-Z to undo the stitch command. This is different from doing the Shell->Unstitch command because during the stitch operation NURBS geometry may be altered and this geometry is not returned to its original state when Unstitched.

When stitching trimmed periodic geometry (for example a primitive sphere or a surface of revolution), you can enable the Detach periodic surfaces option to detach these surfaces into two pieces, ensuring a successful stitching operation.

The option that lets you detach single curve boundaries addresses the passing of stitched geometry from Alias to CAD packages. If a closed trim curve exists, as would result from intersecting a plane with a primitive cylinder and trimming back the plane, this option will detach the closed curve into two pieces.

The Shrink surfaces option ensures that any trimmed surfaces are reduced in physical size to the minimum needed to represent the trimmed part of the surface.

Slicing

When configuring the .slc option box, you can set the output units according to the units the solid imaging software will use to process the .stl file.

Next you can decide whether the geometry should be sliced according to the volume of the geometry bounding box, which is the default setting of Auto Range, or if you can define the minimum and maximum Z height of the volume to be processed.

Thickness refers to the distance between contour lines that will be used to build the part. The average is between 0.006 inches and 0.003 inches but can go as low as 0.0005 inches. This value should be determined by both the designer and the person who will be building the part.

The .slc file can be read back into Alias. You should avoid reading .slc files of a high resolution back into Alias as the size and density of information could make the geometry unmanageable.

Inventor Import/Export

If you have extended SoNodeKit classes in your Inventor files, Studio/PA can only read these nodes if there is a Dynamically Shared Object (DSO) containing the extensions in the path of LD_LIBRARY_PATH. Please read The Inventor Mentor: Programming Object Oriented 3D Graphics with Open Inventor: Release 2, Chapter 11 File Format, Page 17: Reading in Extender Nodes and Engines for further information.

The rest of this section lists the Inventor nodes that are partially supported or not supported by the Inventor import and export translators (IvToAl and AlToIv).

Nodes Not Supported

• The analytical geometry nodes SoCube, SoCubeDetail are not supported directly. However, an Inventor file containing these nodes can be imported if optimization is on.

• The text and camera nodes SoAsciiText, SoText2, SoText3, SoTextDetail, SoLabel, SoFont, SoFontStyle, SoDrawStyle, SoOrthographicCamera, SoTranslation and all their subclasses are not supported.

• The animation nodes SoSensor and SoEngine and their subclasses are not supported.

• The SoLOD and SoLevelOfDetail nodes are implemented as SoGroup and do not fully support the concept of level of detail.