The Development of Support for PMI in STEP AP203E2 and AP214 Tony Ranger Technical Director Theorem Solutions Ltd.

Theorem Solutions : Interoperability Experts

Theorem Solutions : Major Partnerships Siemens PLM Software UG NX, JT, NX I-DEAS, Parasolid Dassault Systemes Catia V5, Enovia, Delmia Parametric Technologies ProE Wildfire, ProductView

Theorem involvement with STEP 1993 : STEP development for CADDS 5 PDES Inc. AeroSTEP pilot Boeing, Rolls Royce, Pratt & Whitney, General Electric AP203 Class 6 Brep Solids 1993-Present Members of PDES Inc. and ProSTEP Participants in CAX-IF (previously STEPNet & ProSTEP Roundtable) Member of AP203 Certification Board Participated in ISO SC4 meetings

Production STEP Processors CADDS 5 UG NX Parasolid CATIA V4 SC03

STEP and 3D PMI Representation Data The semantic information in an intelligent form machine readable Presentation Data The display definition of the information human readable

Example of Simple Dimension What you see here is the presentation

Representation and Presentation Data Representation Data Diameter Dimension Value of dimension 1.0 Plus Minus Tolerance for diameter 0.003 Presentation Data 3 Text Strings : “<0>” “1.000” “<$t>.003” (UG NX) “\S\X” “1.000” “\S\1.003” (STEP) Text font, width, height, character and line spacing WCS Definition Position in WCS Leader line, dimension line, arrowhead symbol definition and placement

Sub Classifications of Presentation Data There are many ways of defining the presentation data. The CAX-IF has defined 3 ways for which recommended practices will be produced. Polyline Presentation Minimal Semantic Presentation Full Semantic Presentation

Polyline Presentation Data Definition of presentation data (my understanding) All display graphics defined as polyline or circular arc 3D geometry.

Minimal Semantic Presentation Data Definition of presentation data (my understanding) The minimum amount of data which, together with the representation data, allows the target system to create the PMI display information in its natural (native) form.

Full Semantic Presentation Data Definition of presentation data (my understanding) A full set of semantic presentation data (text, curves, symbols) such that the PMI display information can be created in the target system.

Some Advantages / Disadvantages Polyline Presentation Polyline is very simple WYSIWYG No intelligence Difficult to validate content

Some Advantages / Disadvantages Minimal Semantic Presentation Minimal Semantics is not WYSIWYG Full intelligence – translated PMI object behaves as native object because it is a native object

Some Advantages / Disadvantages Full Semantic Presentation Full Semantics is almost WYSIWYG Limited intelligence – because it is not created as native semantic PMI object. In UG NX may create “Assorted Parts Dimension” Can be linked with intelligent objects – dependent on system API functionality.

Text Font IGES translation for drawings – the light box test. Different systems have different font tables. Even if fonts have the same name they may not satisfy the window text. STEP provides for the AP to define supported fonts.

STEP Document Structure Resource Parts e.g. Part 42 Product data representation and exchange: Integrated generic resource: Geometric and topological representation AICs e.g. Part 520 Application interpreted construct: Associative draughting elements APs e.g. Part 202 Application protocol: Associative draughting

STEP Entity Definition Context AICs are based on resource parts and extend them for a specific application discipline. Additional subtypes of entities may be created to specialise the meaning of that entity. Application Protocols are built from resource parts and AICs. Any recommended practices produced are specifically relevant to APs which support all of the entity definitions, the rules, the valid defined text strings and select types.

Text Font IGES translation for drawings – the window test. Different systems have different font tables. Even if fonts have the same name they may not satisfy the window text. STEP provides for the AP to define supported fonts. AP 214 : ‘ISO 3098-1 font A’ ‘ISO 3098-1 font B’ AP 203 E2 : ‘ISO 3098’ In addition, there is a capability for non-formal support of fonts. These need to be semi-formalised via recommended practice.

ISO 3098 Technical Product Documentation - Lettering

ISO 3098-1 Font A

Recommended Practice for Text Font text_literal ->font : font_select; font_select = SELECT (pre_defined_text_font, externally_defined_text_font); pre_defined_text_font : SUBTYPE OF (pre_defined_item); pre_defined_item -> name : label; Current recommended practice is to always use a subtype of pre_defined_text_font. draughting_ pre_defined_text_font has rules limiting the content of the name attribute.

New Recommended Practices ? text_literal ->font : either pre_defined_text_font or externally_defined_text_font pre_defined_text_font -> name : label; New Recommended Practice could provide for use of pre_defined_text_font with specifically agreed names. E.g. Arial

New Recommended Practices ? text_literal ->font : either pre_defined_text_font or externally_defined_text_font pre_defined_text_font -> name : label; New Recommended Practice could provide for use of pre_defined_text_font with specifically agreed names. E.g. Arial externally_defined_text_font is a subtype of externally_defined_item source : identifier – for example “UG NX” Item_id : identifier – for example “blockfont”

Recommended Practice for Handling Text Key property of a text string is the space it takes in the display.

Recommended Practice for Handling Text Key property of a text string is the space it takes in the display. This is a PMI note providing some information This is an appended note.

Recommended Practice for Handling Text Key property of a text string is the space it takes in the display. If the space that the text uses is incorrect, it can cause problems. This is a PMI note providing some information This is an appended note. This is a PMI note providing some information This is an appended note.

Recommended Practice for Handling Text Key property of a text string is the space it takes in the display. If the space that the text uses is incorrect, it can cause problems. This is a PMI note providing some information This is an appended note. This is a PMI note providing some information This is an appended note. Recommended Practice : use text_literal_with_extent to define text. During post-processing, select text size properties to ensure the text uses the same extents box.

Combinations of forms of data within STEP Representation Data Useful only for systems which do not require presentation content (e.g. UG NX) Representation Data and Presentation Data Minimal or Full Semantic Presentation Data Presentation Data Full Semantic or Polyline Presentation Data

Associativity CAD systems can retain full associativity of PMI with the underlying geometry. STEP supports associativity of PMI with geometry but it is very cumbersome and yet not as detailed as the native CAD data.

Linear Dimension This is a vertical dimension between the end points of 2 parallel lines.

Linear Dimension This is a vertical dimension between the end points of 2 parallel lines.

Object Associativity Within UG NX the associativity information is quite detailed – the UF_DRF_object_assoc_data structure defines which end of the line is referenced or, for arc edges, can point to the centre of the arc or a tangency point on the arc. Within STEP, the information is much more cumbersome and is not so detailed.

STEP Object Associativity

Linear Dimension to Centre of Arc For this, UG NX has associativity flag to identify referred point as the centre of the arc.

STEP Object Associativity Axis_placement

Derived Associativity Data The STEP associativity is defined but it is not as specific as the data held by the native CAD systems. The STEP post-processors can look for possible relationships – such as tangent point or arc centre point – and can derive the level of information required by the CAD systems but it requires more work.

Complex PMI

Complex PMI

What does it mean to the user? This applies to 6 holes Diameter Dimension Value 3.4 Max limit tolerance plus 0.08 Min limit tolerance -0.025 Depth of hole 6 Max limit tolerance on depth 0.5 Min limit tolerance on depth 0.0 Countersink Diameter 4.1 Max limit tolerance on countersink diameter 0.25 Min limit tolerance on countersink diameter 0. Countersink included angle between 82 and 100 degrees Screw Thread Definition “M4X0.7 – 6H” has a minimum depth of 4 Position tolerance for hole centre has diameter of 0.25 Projected Tolerance Zone has minimum height of 6 Position related to datums D, E, C (in that order)

What does it mean to UG NX It is a diameter dimension It has 6 text strings

What does it mean to UG NX It is a diameter dimension It has 6 text strings

What does it mean to UG NX It is a diameter dimension It has 6 text strings It has a value text : “3.4” It has a prefix text : “6X” The other 4 texts are appended text Most interesting is text object with 3 lines “<#C><0>4.1<T+0.25! 0> X 82<$s>-100<$s>” “M4X0.7-6H <#D>4 MIN” “<&70><+><&10><+><0>0.25<P>6<+>D<+>E<+>C<+><&90>”

Interpreting the data For STEP, this needs to be interpreted into a set of representation entities. dimensional_size plus_minus_tolerance position_tolerance Datums

Interpreting the data For STEP, this needs to be interpreted into a set of representation entities. dimensional_size plus_minus_tolerance position_tolerance Datums But these representation entities leave a lot of information which is not defined.

Interpreting the data For STEP, this needs to be interpreted into a set of representation entities. dimensional_size plus_minus_tolerance position_tolerance Datums Text Data is required to complete the semantic content. Representation data in itself is incomplete.

Full Part PMI Top View of Part

Is it usable? Complex PMI example

Saved View as Work View User Creates sub-set of full PMI to be visible in view

STEP draughting model + camera model The way that the presentation information is gathered together within a part is using a draughting model. The geometry is defined within a shape representation. The draughting model references the geometry from the shape representation and can add additional annotation information in a single presentation. The draughting model can also reference a camera model. The Recommended Practice will state that a draughting model containing a single camera model together with all or a subset of the PMI represents a saved view definition.

Draughting model linked to geometry Extracted from the Polyline Recommended Practice Document

LOTAR Polyline Presentation Project Objective : to create a Recommended Practice document for Polyline Presentation of PMI and to create processors for CATIA V5 and UG NX to demonstrate the capability. Participants : US & European Aerospace companies, ProSTEP, Dassault Systemes and Theorem Solutions. Status : RP document close to final draft, software in final testing stages. Saved Views will be supported in the RP document but not in the initial software.

NIST Semantic Presentation Project Objective : to create a Recommended Practice document for Semantic Presentation of PMI and to create processors for ProE Wildfire and UG NX to demonstrate the capability. Participants : NIST, PDES, PTC and Theorem Solutions. Status : RP document under development, software in early development stages. Saved Views will be supported in the RP document and possibly in the software.

Complex PMI example reflected through STEP Reflected via Polyline Presentation Original Reflected via Full Semantic Presentation

Thank You Questions?