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by Alex Ball (DCC/UKOLN, University of Bath). Presentation given at the DEDICATE final seminar (University of Glasgow, 21st October 2013).
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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
My background
2005
2006
2007
2008
2009
2010
2011
2012
2013
DCC SCARP
DEDICATE Final Seminar 21 October 2013
DPC Technology Watch Report
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PreservingComputer-AidedDesign (CAD)
DPC Technology Watch Report 13-02 April 2013
Alex Ball
http://dx.doi.org/10.7207/twr13-02
DEDICATE Final Seminar 21 October 2013
Outline
Curation challenges for CAD
The CAD format problem
The rationale problem
The contextual problem
Final thoughts
DEDICATE Final Seminar 21 October 2013
Curation challenges for CAD
DEDICATE Final Seminar 21 October 2013
Lasting value of CAD
c� Alexander C. Schreyerc� Field Archaeology Specialists
Public domain c� Worcestershire Archaeological Service
DEDICATE Final Seminar 21 October 2013
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
DEDICATE Final Seminar 21 October 2013
Integration with other systems
CADSystem
CAMSystem
FiniteElementAnalysisSystem
GeographicInformation
System
AnimationSystem
HighQuality
Renderer
. . .
DEDICATE Final Seminar 21 October 2013
Relationship with other documents
CADModel
ArchaeologyDatabase
Bill ofMaterials
ProcessModel
RationaleModel
SystemsModels
. . .
DEDICATE Final Seminar 21 October 2013
The CAD format problem
DEDICATE Final Seminar 21 October 2013
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
DEDICATE Final Seminar 21 October 2013
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 . . .
DEDICATE Final Seminar 21 October 2013
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
DEDICATE Final Seminar 21 October 2013
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
DEDICATE Final Seminar 21 October 2013
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
DEDICATE Final Seminar 21 October 2013
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
DEDICATE Final Seminar 21 October 2013
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?
DEDICATE Final Seminar 21 October 2013
Lightweight models with multilayer annotations
Geometry layer
Classifiedannotations for
designers
Unclassifiedannotations for
manufacture
DEDICATE Final Seminar 21 October 2013
The rationale problem
DEDICATE Final Seminar 21 October 2013
Feature-based modelling
RibsCavities
DEDICATE Final Seminar 21 October 2013
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⇥. . .
DEDICATE Final Seminar 21 October 2013
Automated information capture
User logging
Design/plan
Dataanalysis
Knowledgecapture/
formalization
Non-intrusive engineering
knowledge acquisition
Knowledgestore
c� Raymond Sung/Heriot-Watt University
DEDICATE Final Seminar 21 October 2013
Design Rationale Editor
c� Rob Bracewell/University of Cambridge
DEDICATE Final Seminar 21 October 2013
The contextual problem
DEDICATE Final Seminar 21 October 2013
Transactional records
c�Alastair Conway, Matt Geiss, Bill Ion, Chris McMahon
Engineering workspace
Documentary space
XSLT
DEDICATE Final Seminar 21 October 2013
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
DEDICATE Final Seminar 21 October 2013
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)
DEDICATE Final Seminar 21 October 2013
Research activity information development
http://sourceforge.net/p/raidmap/
DEDICATE Final Seminar 21 October 2013
Final thoughts
DEDICATE Final Seminar 21 October 2013
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!
DEDICATE Final Seminar 21 October 2013
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
DEDICATE Final Seminar 21 October 2013
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