Building 3D content to last

Stephen GrayAssociate

JISC Digital Media

info@jiscdigitalmedia.ac.uk

Content• JISC Digital Media 3D work so far• Culture of data reuse/challenge of reusing 3D• 3D file formats• Significant properties of 3D• Metadata for 3D content• Work yet to be done/conclusions

www.jiscdigitalmedia.ac.uk

• Support for JISC Advance HE/FE/GLAM

• Video, sounds, images & 3D

• Website: ‘good practice guides’

• Mailing list, blog and Twitter

• Helpdesk service

JISC Digital Media 3D Toolkit

• An Introduction to 3D Digitisation

• IPR for 3D Digitisation (with JISC Legal)

• Sharing 3D Content

• Publishing 3D Content Online

• Seminars, workshops & case studies

• Examples of 3D in research...

Augmented Realityin the veterinary science

Motion capturein choreography & sports science

Rapid prototypingin engineering

Culture of data reuse

Data reuse requirements(government, research and heritage)

• Data ‘availability’ mandate from RCUK (2013)

• Publishers (e.g. BMJ) data requirements

• data.gov and more ‘open data’ EU directives likely

• HLF ‘digital outputs’ available for 10 years, usable

for 5 years, post-award

Some reuse expectations

Digital content should typically be:• In a suitable format to support reuse• Adequately described to support

reuse• Available/reusable for x years

Culture of reuse:A 3D problem?

‘Standard’ digital content Digital 3D content

Long-lived file formats clear

Significant properties defined

Metadata standards in place

Long-lived file formats unclear

Significant properties undefined

Metadata standards not in place

3-dimensional challenges

File formats

“We are often inhibited... by the large numbers

of proprietary formats used to analyse, process

and visualise 3D data.”

- Jenny Mitcham, ADS 2012

• Widespread adoption (proprietary often

beats open source)

• Minimal ‘dependencies’ (open often wins)

• Code in public realm (open or ‘semi-open’)

• As simple as possible

‘Standard’ file formatselection criteria

3D file formats: the state of play• Over 166 different 3D file formats in common usage• All are complex (define Geometry, Appearance, Scene

properties, Animation)• Excluding proprietary/undisclosed formats many open

formats exist (e.g. Meshlab outputs: PLY, STL, OFF, OBJ, 3DS, VRML 2.0, U3D, X3D and Collada)

• Some even have ‘sub-formats’ (e.g. DAZ Collada & Autodesk Collada)

• All are different (e.g. Geometry stored as parametric surface, faceted mesh, pointcloud, boundary only or solid geometry)

www.turbosquid.com, a solution in practice:

Common 3D file formats

• .dae (Collada) XML-based format is gaining ground

• .3ds and .obj most commonly used as exchange formats

• .obj is currently still 3D ‘workhorse’

.obj still popular*

Data Description Preservation format (Archiving) Required?

Original raw scan file ASCII TXT and Native Yes

Pre-mesh point cloud ASCII TXT Strongly advised if archiving a derived Polygonal mesh

Polygonal Mesh OBJ + MTL (ASCII) Required if final dataset

Decimated Mesh OBJ + MTL (ASCII) Required if final dataset

*From ADS/AHDS laser scanning good practice guide

http://guides.archaeologydataservice.ac.uk/g2gp/LaserScan_3-1

• Image and Spatial Data Analysis Group (ISDA)

Conversion Software Registry

– Repository of info on conversion software

– Complements ‘file format registries’ (e.g. PRONOM)

• ISDA’s own software tools for 3D conversion at

http://isda.ncsa.illinois.edu/drupal/

3D formats: useful tools

Q. Format.x seems best, will it last?

A. No

All file formats will become obsolete and will need to be updated over time.

We must ensure 3D content continues to ‘perform’ in the same ways, independent of format.

Significant Properties

• Updating/converting formats = information loss• Important to ensure files still ‘perform’ in the same

way as before• Files should convey the essence of a digital record• Files akin to a musical score (rather than a

gramophone record)

Significant Properties

• Files ‘do’ lots of things, what do we really care about?

• Defined as significant properties• Ensure these are maintained,

regardless of current or future file type

• Documented as metadata...

Metadata and 3D content

Metadata• Actual data is the 3D model, metadata describes the

3D model

• Searchable, can be queried used for browsing (and

managing) digital content

• 3D-specific standards slowly emerging

• Back to www.turbosquid.com...

Metadata@turbosquid

MetadataMetadata for 3D Models (Boeykens, Bogani 2011)

suggest the following are also described:

• Are any materials used physically correct?

• Are advanced shaders/plug-ins used?

• Are layers or components present?

• Is lighting/physically correct lighting used?

• List any external files required

MetadataThe POCUS* project suggests we also describe:• Audience and type of interaction expected (i.e. who is the

model aimed at and how can they interact with it?)• Methods and techniques used to create a model

(hardware model numbers, software versions etc.)• Datasets used to create a 3D model (e.g. laser scanning,

geophysics, lidar)• Flag when features of a model based on estimation

rather than evidence

*The preservation of complex objects (POCOS) Vol.1,

Visualisations and simulations, 2012

Conclusions

Work yet to be done

• Significant properties of 3D should be communally

defined (extend INSPECT work?) to save

duplication of effort

• A shared (if basic) 3D technical metadata standard

could be defined and adopted by repositories

• The shortage of 3D digitisation training with a public

sector focus should be addressed

ConclusionThe sharing of 3D content is complex. It would

ideally be considered (and costed) before any

content is created.

Archiving is far easier when repositories (museums,

archives, universities or similar) work alongside the

creators of 3D content with preservation as the

common goal.- paraphrasing ADS

info@jiscdigitalmedia.ac.uk