Geometric Modeler

Using the CGM Data Checker

Technical Article

Abstract

CGM objects are valid if they fulfill a certain number of rules. When a given object is created, it can be checked for a given rule. If any problem is found, a core dump is issued and the developer has to take a look at the core dump traces to get some clue about why the object is invalid. The rule checker itself is a detection tool which does not repair any object. If no core dump has been issued, this only means that the CGM object to be validated complies with a specified rule. Other rules may not be fulfilled making the object invalid.

The Rules to be Satisfied
How to Activate the Rules
The Topological Checks
The Geometrical Checks

The Rules to be Satisfied

Each rule is defined by an identifier. This identifier is used to activate the data checker as described in How to Activate the Rules.

*Rules to be checked*	*Identifiers*
A body should not contain any touched topology	TRE_1
A closed wire should be made up of at least two edges	CWE_1
A topologically smooth edge should be geometrically smooth	ESH_1
A loop should not be closed in 3D and open in 2D	SCE_0
A CATPointOnEdgeCurve should be on its EdgeCurve	PCE_1
Any CATCrvParam of a POEC should be in the maximum limits of its spec curve.	PPO_1
The gap between the curves making up a CATINTCurve should be less than the resolution	ICG_1
Limit Box of a PCurve curve should be inside the Support's limits box. (Check for PCurve :: CloneAndMove service)	PSS_0
Limit Box of a PCurve curve should be inside the Support's limits box. (Check for PCurve :: SetSurface service)	PSS_1
Curve continuity should be at least C1	CCC_0
Surface continuity should be at least C1	CCC_1
SetOfPointsMapping for curve limits inclusion for CATSetOfPointsMapX for ref/co curves of an edge curve should be within the resolution	SPM_1
The internal gap in a macro point should be less than the resolution.	MPG_1
Check for ref curve and curve from MapX for an edge curve, that curve useful limits are included in it's max limits.	ULO_0
Curve continuity OK in V5 (at least C2)	CGC_0
Surface continuity OK in V5 (at least C2)	CGC_1
The EdgeCurve should not have identical PCurves in the same tree	EIP_1
The MathRep of canonical curves (Circle & Ellipse) should be in the model infinite	INF_2

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How to Activate the Rules

Here are the preliminary steps to follow prior to activating the data checker:

Step 1

either create a CATIA environment CATIA, edit it and modify the value of the CATICPath variable.

<install_CATIA>\intel_a\code\productIC

should be modified in

<install_CATIA>\intel_a\code\productIC;<install RADE>\intel_a\code\productIC

Note that from CATIA V5R14, you can install RADE and CATIA at the same place.

or copy the contents of <install RADE>\intel_a\code\productIC into <install_CATIA>\intel_a\code\productIC

Step 2

Activate CDC licence in the Tools/Option Licencing Menu.

Step 3

Exit CATIA, activate the CATCAADataChecker variable plus the appropriate rule variables as described below:

set CATCAADataChecker=1
to activate all the rules

set CATCAADataChecker=1
set CATCGMCleanerRules=XXX_1;YYY_1 ;...
to activate only a set of rules
XXX_1, YYYY_1 are the rule identifiers

2. Restart CATIA.

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The Topological Checks

Body should not contain any touched topology

A cell is touched when it is intended to be used in some specific operations like the "smart duplication" (see the CATSmartBodyDuplicator in the CAA Encyclopedia). Note there is other operators that require touched objects as their input data. After the operation has completed the touched cells should return to an untouched status. If they remain touched, further operations on the initial body may lead to unexpected results. A valid topology should not contain any touched cells.

The CD traces are similar to the ones below:

CGM Rule : TRE_1 Short msg : "Residual touched cells checking failed."; Extended msg : "Residual touched cells on ... checking failed.";

A closed wire should be made up of at least two edges

An edge cannot be closed on itself, in other words any closed wire should be made up of at least two edges.

CGM Rule : CWE_1 Short msg : "Closed wire with edgecount > 1 checking failed."; Extended msg : "Closed wire with edgecount > 1 on ... checking failed.";

A topologically smooth edge should be geometrically smooth

The edges that are considered as smooth should not have a geometrical sharpness greater than 2.3 deg. If there is no consistency between topological and geometrical sharpness, operations such as fillets and offset cannot succeed.

CGM Rule : ESH_1 Short msg : = "Edge sharpness checking failed."; Extended msg: "Edge sharpness on /p1 checking failed.";

A loop should not be closed in 3D and open in 2D

A loop relying on a surface should not be closed on itself. For example, a cylinder should not be made up of one single loop. In the right-hand side figures, the first one exhibits an invalid loop.

The CD traces are similar to the ones below:

CGM Rule: SCE_0 On CGM Object: ... From Feature: ... Short msg: "Surface closure for Loop checking failed."; Extended msg: "Surface closure for Loop ... checking failed.";

A CATPointOnEdgeCurve should be on its EdgeCurve

Reminder: An CATPointOnEdgeCurve is specified by couples of data including a CATCrvParam and the CATCurve associated with this CATCrvParam. The list of data couples is referred to as a "spec". The "spec" defines a CATPointOnEdgeCurve. The EdgeCurve itself is made up of several curves. When scanning and analyzing each spec curve of a CATPointOnEdgeCurve by using CATPointOnEdgeCurve::GetSpec for example, one should find that each retrieved CATCurve is contained into the CATEdgeCurve.

CGM Rule : PCE_1 On CGM Object : ... From Feature : ... Short msg : "POEC curve in edge curve checking failed."; Extended msg: "POEC curve in edge curve on ... checking failed.";

Any CATCrvParam of a POEC should be in the maximum limits of its spec curves

When scanning and analyzing each spec curve of a CATPointOnEdgeCurve, one should find that each retrieved CATCrvParam is within the limits of the reference curve.

CGM Rule : PP0_1 On CGM Object : ... From Feature : ... Short msg : "POEC spec param inside spec curve limits checking failed."; Extended msg: "POEC spec param inside spec curve limits on /p1 checking failed.";

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The Geometrical Checks

The gap between the curves making up a CATINTCurve should be less than the resolution

Checks the Gap between the corresponding points of component curves of a CATIntCurve.

CGM Rule : ICG_1
On CGM Object : CATIntCurveType
From Feature : ...
Short msg : "IntCurve gap less than resolution checking failed.";
Extended msg: "IntCurve gap less than resolution on /p1 checking failed.";

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Limit Box of a PCurve curve should be inside the Support's limits box. (Check for PCurve :: CloneAndMove service)

Checks whether the limits of PCurve are included in the limits of its support. The check is called from PCurve :: CloneAndMove method

CGM Rule : PSS_0 On CGM Object : CATPCurveType From Feature : ... Short msg : "PCurve outside its support."; Extended msg: "PCurve outside its ... support..";

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Limit Box of a PCurve curve should be inside the Support's limits box. (Check for PCurve :: SetSurface service)

Checks whether the limits of PCurve are included in the limits of its support. The check is called from PCurve :: SetSurface method

CGM Rule : PSS_1
On CGM Object : CATPCurveType
From Feature : ...
Short msg : "PCurve outside its support.";
Extended msg: "PCurve outside its ... support..";

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Curve continuity should be at least C1

Checks whether the Curve is C1 continuous

CGM Rule : CCC_0
On CGM Object : CATCurveType
From Feature : ...
Short msg : " Curve continuity is at least C1 checking failed.";
Extended msg: " Curve continuity is at least C1 on /p1 checking failed.";

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Surface continuity should be at least C1

Checks whether the Surface is C1 continuous

CGM Rule : CCC_1
On CGM Object : CATSurfaceType
From Feature : ...
Short msg : " Surface continuity is at least C1 checking failed.";
Extended msg: " Surface continuity is at least C1 on /p1 checking failed.";

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SetOfPointsMapping for curve limits inclusion for CATSetOfPointsMapX for ref/co curves of an edge curve should be within the resolution

For every point in SetOfPointsMapping, the geometrical distance between the reference curve and the other curves of the map should be less than the factory resolution.

CGM Rule : SPM_1

On CGM Object: CATEdgeCurveType
From Feature: ...
Short msg : " EdgeCurve SetOfPointsMappingLimits checking failed.";
Extended msg: " EdgeCurve SetOfPointsMappingLimits on /p1 checking failed.";

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The internal gap in a macro point should be less than the resolution.

Checks the Gap between the component POECs of the MacroPoint. The distance is measured between one reference point and other points.

CGM Rule : MPG_1

On CGM Object : CATMacroPointType
From Feature : ...
Short msg : " Macro Point has a too big gap between its internal points.";
Extended msg: " Gap inside Macro Point on /p1 checking failed.";

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Check for ref curve and curve from MapX for an edge curve, that curve useful limits are included in its max limits.

The useful limits of the RefCurve and curves of an EdgeCurve should be included in the maxlimit of edge curve.

CGM Rule : ULO_1

On CGM Object : CATEdgeCurveType
From Feature : ...
Short msg : " Curve Limits - Useful Outside Max checking failed.";
Extended msg: " Curve Limits - Useful Outside Max on /p1 checking failed.";

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Curve continuity should be at least C2 in V5

The curve should be at least C2 continuous in V5.

CGM Rule : CGC_0

On CGM Object : CATCurveType
From Feature : ...
Short msg : " Curve continuity checking failed.";
Extended msg: " Curve continuity on /p1 checking failed.";

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Surface continuity should be at least C2 in V5

The surface should be at least C2 continuous in V5.

CGM Rule : CGC_1

On CGM Object : CATSurfaceType
From Feature : ...
Short msg : " Surface continuity checking failed.";
Extended msg: " Surface continuity on /p1 checking failed.";

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The edge curve should not have identical PCurves in the same tree

The edge curve should not contain identical PCurves in the same tree. But they can exist in different trees.

The EdgeCurve-EC has one PCurve (PC) and one Merged Curve (MC) which again has two component PCurves.

The First case is OK because PC1 is in different trees.

The second case is KO because both PC2 s are in the same tree.

CGM Rule : EIP_1

On CGM Object : CATEdgeCurveType
From Feature : ...
Short msg : " The EdgeCurve Should Not Have Identical PCurves In The Same Tree checking failed.";
Extended msg: " The EdgeCurve Should Not Have Identical PCurves In The Same Tree on /p1 checking failed. ";

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The MathRep of the canonical curves (Circle & Ellipse) should be in the model infinite

Authorized: the mathematical circle (in dashed green) is in the infinite.

Not authorized: the complete mathematical circle (in dashed green) is not in the infinite.

Definition of Model Infinite & Model space

Until CATIA V5 R13

From CATIA V5 R14

Model Size

[-100 meters, + 100 meters]
on each coordinate

[-1 000 meters, + 1 000 meters]
on each coordinate

Model infinite

[-1 000 meters, + 1 000 meters]
on each coordinate

[-10 000 meters, + 10 000 meters]
on each coordinate

CGM Rule : INF_2 On CGM Object : CATCircleType, CATEllipseType From Feature : ... Short msg : " Circle/Ellipse - MathRep Inside Model Infinite checking failed. "; Extended msg: " Circle/Ellipse - MathRep Inside Model Infinite on /p1 checking failed. ";

History

Version: 1 [Aug 2004]	Document created
Version: 2 [July 2005]	Document modified
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