Changing NZ Map Projections
Changing NZ Map Projections

Geographic Coordinate System (WGS84)
Tip of Christchurch Spit = 177 44’ 55.13 E, 43 33’ 43.81 S (long/lat)

1949?: New Zealand Yard Grid(s)
Separate North & South Island Grids, coordinates = yards
Tip of Christchurch Spit = 610290 E, 552170 N ‘SIYG’ (or NIYG?!)

1973: New Zealand Map Grid (NZMG)
One Grid to rule them all, local datum NZGD1949, coordinates = meters.
Tip of Christchurch Spit = 2489700 E, 5738300 N NZMG

2001: New Zealand Transverse Mercator (NZTM)
New technology (GPS & GIS), geocentric datum NZGD2000, coordinates =
meters.
Tip of Christchurch Spit = 1579660 E, 5176560 N NZTM
Changing NZ Map Projections
NZMG or NZTM?
.000000
2200000
.000000
2400000
2400000
.000000
2600000
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2600000
.000000
2800000
.000000
3000000
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2800000
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.000000
.000000
1200000
.000000
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.000000
1600000
.000000
1800000
.000000
2000000
.000000
.000000
1200000
.000000
1400000
.000000
1600000
.000000
1800000
.000000
2000000
.000000
.000000
6100000
.000000
6100000
.000000
5800000
.000000
5800000
.000000
.000000
5500000
.000000
5500000
.000000
.000000
5200000
.000000
5200000
.000000
.000000
4900000
4900000
.000000
.000000
1000000
4600000
5300000
.000000
5600000
.000000
5900000
.000000
6200000
.000000
6500000
.000000
6800000
.000000
2000000
2200000
.000000
.000000
2000000
.000000
.000000
5600000
5900000
6200000
6500000
6800000
1000000
.000000
Changing NZ Map Projections
mix ‘n’ match

NZGD1949 coordinates use a local datum, while the
NZGD2000 coordinates use a geocentric datum. The two
datums use different shaped ellipsoids. As a result, the
NZGD49 and NZGD2000 coordinates for the same point
differ by approximately 200 metres (approximately 10
metres in the east and 190 metres in the north directions).
Coordinates can be converted from one datum to another based on
transformation parameters derived from survey control stations which
have coordinates on both datums ( more is better).
Changing NZ Map Projections
and Geographic Information Systems (GIS)

NZ Census 1996 Deprivation Data Meshblock Boundaries
(and road centerlines) in NZMG, overlain with address
points in NZTM, from the LINZ Core Record System (CRS)
(previously the Digital Cadastral Database DCDB).
Legend
Address points
Roads
Meshblocks
NZ DEPRIVATION 1996
0-1
1-3
3-6
6-8
8-10
GIS in Schools
NEW ZEALAND
•Increasing number of schools use GIS for technology skills
•Hardware, software, data, and curriculum material is
increasingly available
•Puts technology in a (spatial) context we can all relate to
•Google Earth, Wises Maps, Yellow pages, Harcourts…
•Steep learning curve = time + support = GISMAPED
GISMAPED
http://www.gismaped.co.nz



GISMAPED is a company providing professional development
through high quality, practical, curriculum oriented workshops to
teachers of Y5-13 Social Studies, History, Geography and Science,
and to schools involved in the GLOBE programme.
Site includes details of upcoming Workshops, access to resources,
links to other related sites and information regarding qualifying for
the Eagle Technology GIS In schools programme.
Anne Olsen [email protected] or Stephanie Eddy
[email protected]
References
Changing NZ Map Projections
Land Information New Zealand: http://www.linz.govt.nz
> Survey System> Geodetic Information> Projections & Datums
~/docs/surveysystem/survey-publication/witwaw.pdf
Ollivier & Co: http://www.ollivier.co.nz
~/projection/faq.shtm
GIS in Schools
GISMAPED: http://www.gismaped.co.nz
~support, curriculum material…
Eagle Technology (NZ): http://egis.eagle.co.nz/schools
~ FAQ, list server/email list, sponsorship deals might be dated.
Environmental Systems Research Institute (ArcGIS
ArcView/Arcinfo…): http://www.esri.com
~virtual campus, online help
UC GEOG: http://www.geog.canterbury.ac.nz/links
~facilities for teacher workshops, and maybe school visits?