CATIA V5 (Windows only)

Alias CATIA V5 DirectConnect is a stand-alone utility that allows the exchange of 3D model data between Alias and CATIA V5 using the native CATIA part (.CATPart) and product (.CATProduct) files.

CATIA Requirements

CATIA V5 (Release 6 - 18).
Version 2013 of an Alias software product.
Windows operating system.

See Before you create the model for a list of modeling practices to use as a quick reference guide if problems arise.

Before you create the model

Set units to mm.

Set optimal tolerances in accordance with CATIA V5. The default tolerances are:
- Curve Fit Distance = 0.001 mm
- Curve Fit Checkpoints = 10
- Max Gap Distance = 0.001 mm
- Trim Curve Fit = 0.005 mm
- Topology Distance = 0.02 mm

(CATIA tolerances are set for large scale objects as well as for normal scale objects.)

While you create the model

Periodically transfer models from Alias to CATIA during construction to manage the quality of the model being created.
The Alias model should be capable of being successfully stitched before export. If you periodically stitch the geometry to ensure that the model meets all tolerance requirements, you’ll have a good indication of whether the final model will stitch correctly.
Avoid using Object Edit > Attach > Attach since this function creates multiknots in Alias geometry that may result in unusable geometry in CATIA.
Use surface building tools such as Square and Rail Surface, taking advantage of the Boundary Rebuild option to control curvature continuity between surfaces and ensure that surfaces do not contain multi-knots.
Use Evaluate > Check Model to be alerted to potential problems: it’s another good practice.

Workflow

Before transferring geometry between Alias and CATIA, consider the purpose of the transfer to plan an appropriate workflow. Two common workflows are:

Geometry (describing mechanical components) is transferred from CATIA to Alias for concept design surfacing, then those Alias surfaces are transferred back to CATIA.
A Alias model is transferred to CATIA, and both Alias and CATIA databases are developed independently. Later, the modified Alias model is transferred again to CATIA, replacing the Alias geometry from the first transfer. In this scenario, all work done in CATIA on the first Alias model transfer will affect the new, modified geometry.

There are many variations on these two examples. Whatever the transfer scenario, carefully plan the transfer process, to ensure that the appropriate data is written out and is useful.

What are the curve fit distance tolerances in Alias

The Curve Fit Distance is the tolerance to which trim boundaries are rebuilt to (or approximated). The default positional tolerance in CATIA V5 is 0.001 mm, and the AliasCurve Fit Distance setting should be set to 0.001 mm.

This Curve Fit Distance setting should normally be accurate. If you find that it is not resulting in Alias geometry that can be successfully used in CATIA, then experiment with the Curve Fit Distance—it can set to as low as 0.001 mm. This setting will enhance the success of post transfer processes, such as skinning, that are to be carried out once the geometry is in CATIA.

Tip

Do not set the Curve Fit Distance tolerance in Alias at less than 0.001 mm. Lower than this will affect processing time.

Whether you are creating a model, verifying a model, or debugging a translation, there are a number of tools in Alias you can use to check the quality of the geometry you have created. The most useful tool is the Locators > Deviation Min/max measurement tools. Use this tool to check the maximum distance between any two surface boundaries.