preserving computer-aided design, digital preservation coalition report

because good research needs good data

Preserving Computer-Aided DesignDigital Preservation Coalition Report

Alex Ball

DCC/UKOLN, University of Bath

21 October 2013

Glasgow University

Except where otherwise stated, this work is licensedunder Creative Commons Attribution 2.5 Scotland: http://creativecommons.org/licenses/by/2.5/scotland/

Supported by

DEDICATE Final Seminar 21 October 2013

http://creativecommons.org/licenses/by/2.5/scotland/

http://creativecommons.org/licenses/by/2.5/scotland/

My background

2005

2006

2007

2008

2009

2010

2011

2012

2013

DCC SCARP


DPC Technology Watch Report

01000100 01010000 01000011

01000100 01010000 01000011

01000100 01010000 01000011

PreservingComputer-AidedDesign (CAD)

DPC Technology Watch Report 13-02 April 2013

Alex Ball

http://dx.doi.org/10.7207/twr13-02



Outline

Curation challenges for CAD

The CAD format problem

The rationale problem

The contextual problem

Final thoughts


Curation challenges for CAD


Lasting value of CAD

c� Alexander C. Schreyerc� Field Archaeology Specialists

Public domain c� Worcestershire Archaeological Service


http://blogs.umass.edu/bct420-schreyer/syllabus/

http://guides.archaeologydataservice.ac.uk/g2gp/Cad_1-3

https://commons.wikimedia.org/wiki/File:I11loc.jpg

http://guides.archaeologydataservice.ac.uk/g2gp/Cad_Cs1

Nature of CAD systems

… Typical CAD system: new version every 6 months, end-of-lifeafter 10 years.

… Dependence on particular modelling kernel… Intense competition between vendors for customers

… Innovation: new features being added… Need to retire old systems! time-limited licences… Fear of losing customers to rival systems! lock-in


Integration with other systems

CADSystem

CAMSystem

FiniteElementAnalysisSystem

GeographicInformation

System

AnimationSystem

HighQuality

Renderer

. . .


Relationship with other documents

CADModel

ArchaeologyDatabase

Bill ofMaterials

ProcessModel

RationaleModel

SystemsModels

. . .


The CAD format problem


Software emulation

Pros… CAD model unchanged

Cons… Licence may not allow it… Need to preserve expertise in the system… Hard to maintain integration with newer systems


Rolling format migrations

Pros… Models stay usable by current designers and systems

Cons… Incremental data loss/corruption… Each migration needs to be validated, problems resolved… Migration path may run out . . .


Normalisation

Pros… Limited data loss… Support for archival format likely to improve rather than

degrade over timeCons… Some data loss/corruption… Migration needs to be validated, problems resolved


Normalisation: full exchange formats

DXF: DWG Exchange Format… Not enough documentation?

STEP: ISO 10303… Too much documentation? Key parts:

… Part 21: Clear text encoding of the exchange structure (‘STEPfile’)

… AP 203: Configuration controlled 3D designs of mechanical partsand assemblies

… AP 214: Core data for automotive mechanical design processes… AP 242: Managed model-based 3D engineering

… CAx Implementer Forum… Basis for other standards, e.g. IFC, LOTAR


Normalisation: visualisation formats

Standards

U3D Universal 3D – ECMA-363X3D ISO/IEC 19775, 19776, 19777IGES Initial Graphics Exchange Specification – ANSI

Y14.26M-1981 . . . ANS US/PRO/IPO-100-1996PRC Product Representation Compact – ISO/PRF 14739

JT ISO 14306Non-standards

DWF/DWFx AutoCAD DWG Web Format3D XML CATIA visualisation format


FACADE recommendations

CAD models should be stored in1. the original format2. a full exchange format, e.g. STEP3. a desiccated format, e.g. IGES4. an access format, e.g. 3D PDF


Validation

c� ITI/SNECMA

Example fromLOTAR International

1. Generate pointcloud in originalsoftware

2. Export tonormalisationformat

3. Import into newsoftware

4. Overlay pointcloud: do thepoints still lie onsurfaces/edges?


http://www.dpconline.org/component/docman/doc_download/478-2010julycadbarker

Lightweight models with multilayer annotations

Geometry layer

Classifiedannotations for

designers

Unclassifiedannotations for

manufacture


The rationale problem


Feature-based modelling

RibsCavities


Construction history modelling

1. Insert cylinder l = 20 r = 1.0

Change cylinder l = 40 r = 0.5

2. Insert sprocket r = 3.0

3. Fit sprocket to cylinder

4. Group cylinder and sprocket

5. Scale group by 1.75⇥. . .


Automated information capture

User logging

Design/plan

Dataanalysis

Knowledgecapture/

formalization

Non-intrusive engineering

knowledge acquisition

Knowledgestore

c� Raymond Sung/Heriot-Watt University


Design Rationale Editor

c� Rob Bracewell/University of Cambridge


The contextual problem


Transactional records

c�Alastair Conway, Matt Geiss, Bill Ion, Chris McMahon

Engineering workspace

Documentary space

XSLT


Key ERIM Research Findings

1. Poor framework for… pre-project considerations of data management;… data management during the research;… during-project data management for post-project re-use.

2. Poor knowledge of context in which data were generated:… engineering research data is very diverse;… large number of diverse research data records;… relations between data records complex.

3. Knowing the context is vital for understanding data.

Slide: Mansur Darlington


Collecting metadata

Minimum Mandatory Metadata Set; REDm-MED version at:http://opus.bath.ac.uk/30372/

… Drew on PREMIS for preservation metadata… Drew on DataCite for descriptive metadata… Excluded metadata that could easily be generated later… We looked for ways to collect it automatically

(NB: an extensive specification of what metadata to collect forarchaeological CAD can be found at:http://guides.archaeologydataservice.ac.uk/g2gp/Cad_Toc)


http://opus.bath.ac.uk/30372/

http://guides.archaeologydataservice.ac.uk/g2gp/Cad_Toc

Research activity information development

http://sourceforge.net/p/raidmap/


http://sourceforge.net/p/raidmap/

Final thoughts


Recommendations

… Establish why a CAD model will be kept, then target therequired properties for preservation.

… Create tests that can prove whether these properties havesurvived.

… Keep native CAD models for as long as they can be read.… Normalise to STEP and a visualisation standard (or two).… Don’t forget supporting documentation, especially local

conventions, ‘house style’, specifications, rationale records . . .… Campaign for better support for standard formats in CAD

systems!


because good research needs good data

Thank you for your attention

DCC Website: http://www.dcc.ac.uk/Alex Ball: http://alexball.me.uk/

Preserving CAD DPC Technology Watch Report:http://dx.doi.org/10.7207/twr13-02


http://www.dcc.ac.uk/

http://alexball.me.uk/
