ITM - - Irish Transverse Mercator · ITM – GPS Compatible Mapping. Survey Ireland 2007, Malahide...

ITM – GPS Compatible Mapping

Survey Ireland 2007, Malahide 15th May 2007

ITM ITM -- Irish Transverse MercatorIrish Transverse MercatorA ‘GPS’ Compatible Reference System

Survey Ireland 2007

ITM Tutorial

Colin Bray, Ordnance Survey Ireland



• What is ITM?

• Why was ITM developed?

• Irish Grid / ITM comparison

• ITM lineage

• Benefits of ITM

• Implementation Issues

• Transformation utilities

• How can OSi help implementation

• Questions & answers

ITMITM



What is ITM ?What is ITM ?

ITM is a GPS compatible mapping system that takes advantage of the accuracy of GPS whilst minimising mapping distortions

– GPS compatible (no transformations required)

– Takes advantage of the accuracy of ETRF89

– Minimises mapping distortions



Why was ITM developed?Why was ITM developed?

• Extensive use of GPS in geomatics

• Need for geometric interoperability (GPS & geographic data)

• International compatibility

• Shortcomings of the ‘Irish Grid’

– Legacy distortion issues– Not GPS compatible– Dependant on transformation relationship to GPS– Can only realise IG to better than 1m using GPS



IIGG IITTMM

Reference Ellipsoid

Airy (modified)

GRS80

Central Meridian

8° West

8° West

Scale on CM

1.000 035

0.999 820

True Origin ø λ

53° 30' North 8° West

53° 30' North 8° West

False Origin

200 000 W 250 000 S

600 000 West 750 000 South

Mapping System ParametersMapping System Parameters



Irish Grid & ITM ComparisonIrish Grid & ITM Comparison

‘Irish Grid’

Mapsheet ‘ITM’

Mapsheet



ITM & Irish GridITM & Irish Grid

• 400,000 / 500,000 coordinate difference

• Relationship defined via official OSi / OSNI polynomial transformation

– between ETRF89 and Ireland 1975 (accuracy better than 1m everywhere in Ireland)



Development of ITMDevelopment of ITM



ITM LineageITM Lineage• 1999 – Concept introduced at ‘Survey Ireland 1999’ conference

• 2000 – Preliminary user information circulated

• 2001 – Consultation paper circulated

• 2001 – ITM Seminar road show (Cork, Belfast, Dublin, Galway)

• 2001 – ITM parameters formally adopted at ‘Survey Ireland 2001’

• 2002 – OSi converts production flowlines to ITM

• 2002/3 – ITM Technical Working Group

• 2002 – ‘Grid InQuest’ transformation utility available

• 2002 – On-line transformation utility available on OSi website

• 2003/7 – ITM presentations at various user groups / conferences

• 2004 – Irish Institution of Surveyors (IIS) recommends ITM adoption

• 2005 – Land Registry goes digital with ITM



ITM Consultation ProcessITM Consultation Process



IIS Recommends Adoption of ITM to SurveyorsIIS Recommends Adoption of ITM to Surveyors



What are the benefits of ITM?What are the benefits of ITM?

• A more accurate coordinate reference system– with the realisation of ETRF89 (IRENET95)

• Geometric interoperability between mapping and modern surveying instrumentation

– Relationship not dependent on transformations

• Mapping distortions are minimised

• International compatibility

• Consistent standard / framework for relating geographic information



Implementation IssuesImplementation Issues

• Accessing ITM data

• Viewing ITM data

• Converting between Irish Grid and ITM

• Relating ITM to legacy Irish Grid paper records

• Implementation phases

– Maintain existing Irish Grid geographic records and output in ITM format when required

– Fully implement ITM across all systems and data



ITM Technical Working Group (TWG)ITM Technical Working Group (TWG)

Members

• BKS Surveys

• Bord Gais

• Cork City Council

• Electricity Supply Board

• ESBI Computing

• European Air Surveys

• GPS Surveys

• Irish Institution of Surveyors

• Land Registry Ireland

• Land registry Northern Ireland

• LGCSB

• NTL Northern Ireland

• Ordnance Survey Ireland

• Ordnance Survey of Northern Ireland

• Proteus Solutions

• Translink



ITM TWGITM TWG

Key Issues

• Data migration

• Grid / sheet indexing

• Legal issues



Data MigrationData Migration

Key Issues for consideration

• User education

• Software (vendor products)

• Application developers

• OSi / OSNI datasets

• Raster maps and aerial photography



Grid IndexingGrid Indexing

• The ITM TWG recommended a grid index referencing system based on a 1km x 1km grid to be associated with the ITM mapping system

• ITM grid coordinate dimensions:– Min 400,000.000 Easting (m) 500,000.000 Northing (m)– Max 800,000.000 “ 999,000.000 “

• Therefore a 1km x 1km grid index reference system would require a 6-digit numeric to uniquely refer to a specific 1km x 1km grid location (bottom left hand corner)

• Example:– ITM grid coordinate reference = 600,850



Legal IssuesLegal Issues

• The only precedent to this situation was the migration of data from the Cassini projection to Irish Grid in the 1960’s

• There is no evidence of any legal issues arising from that transition. As none of the TWG members enquires have identified potential legal difficulties, it was concluded that, at this point in time, there are no obvious legal impediments to the introduction and use of ITM.



Data MigrationData Migration

• The main issue affecting successful migration to ITM is project management. The basic migration process is well defined, but requires detailed planning, control and quality assurance.

• If properly planned and managed, the migration to ITM will be equivalent to a complete update of existing third party data, and a new release of software.

• With proper planning, migration to ITM can be achieved within the normal timescales for new releases of software and base datasets

• The involvement of the software application providers and the software developers is key to successful migration



Transformation Utilities

Currently available

• Interactive coordinate conversion on OSi website www.osi.ie

• Down loadable coordinate converter shareware from OSi website www.osi.ie

Required

• All major GIS software vendors to implement polynomial transformation

http://www.osi.ie/

http://www.osi.ie/



How can OSi help with implementationHow can OSi help with implementation

• Providing software application providers and software developers with the required software (DLL & developers manual) to facilitate the implementation of data conversion at the user application end

• Setting up a software application provider / software developer user group to progress their implementation of file conversion utilities

• Facilitating dual supply of ITM & Irish Grid during transitional phase

• Developing a shareware look-up utility that will enable users to easily relate the 1:5,000 sheet index to ITM



Thank you for your attentionThank you for your attention

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