Projections and Datums

What is a datum ?

A datum (or geodetic datum) is a reference system. Generally, the Earth is modelized as an ellipsoid, and it is associated to a prime meridian, often the Greenwich meridian. The datum generally used is WGS84.

For more information, see the Wikipedia article.

What is a projection ?

As the Earth is not flat, it is impossible to accurately represent its surface on a map plane without deformations. Many mathematical methods have been developed to obtain plane representations of the Earth. Most famous projections are the Mercator projection, the Lambert Conformal Conic projection and the UTM projection.

For more information, see the Wikipedia article.

Datums and projections supported by ttMaps

The database of datums and projections contains only data that has been checked by myself or by ttMaps users. Here is the current list:

Zone Datum Projection Description EPSG Code
World WGS84 MRWORLD2 Mercator, east of Greenwich 3395
WGS84 MRSPHERIC Spherical Mercator (Google Maps, Yahoo Maps, ...) 3857
WGS84 PCWORLD Plate Carrée 32662
WGS84 MRWORLD Mercator
WGS84 NUTM28 WGS84 / UTM zone 28 North 32628
WGS84 NUTM29 WGS84 / UTM zone 29 North 32629
WGS84 NUTM30 WGS84 / UTM zone 30 North 32630
WGS84 NUTM31 WGS84 / UTM zone 31 North 32631
WGS84 NUTM32 WGS84 / UTM zone 32 North 32632
WGS84 NUTM33 WGS84 / UTM zone 33 North 32633
WGS84 NUTM34 WGS84 / UTM zone 34 North 32634
WGS84 NUTM35 WGS84 / UTM zone 35 North 32635
WGS84 NUTM36 WGS84 / UTM zone 36 North 32636
WGS84 SUTM19 WGS84 / UTM zone 19 South 32719
WGS84 SUTM40 WGS84 / UTM zone 40 South 32740
WGS84 SUTM49 WGS84 / UTM zone 49 South 32749
WGS84 SUTM50 WGS84 / UTM zone 50 South 32750
WGS84 SUTM51 WGS84 / UTM zone 51 South 32751
WGS84 SUTM52 WGS84 / UTM zone 52 South 32752
WGS84 SUTM53 WGS84 / UTM zone 53 South 32753
WGS84 SUTM54 WGS84 / UTM zone 54 South 32754
WGS84 SUTM55 WGS84 / UTM zone 55 South 32755
WGS84 SUTM56 WGS84 / UTM zone 56 South 32756
WGS84 GEODETIC Longitude/latitude 4326
WGS84 MILLER Spherical Miller (IGN Geoportal)
WGS84 ROBINSON Robinson projection
WGS84 CIAROBIN Robinson projection used by the CIA World Factbook
Australia GDA94 GEODETIC GDA94 / Longitude/Latitude 4283
GDA94 MGA49 GDA94 / MGA zone 49 28349
GDA94 MGA50 GDA94 / MGA zone 50 28350
GDA94 MGA51 GDA94 / MGA zone 51 28351
GDA94 MGA52 GDA94 / MGA zone 52 28352
GDA94 MGA53 GDA94 / MGA zone 53 28353
GDA94 MGA54 GDA94 / MGA zone 54 28354
GDA94 MGA55 GDA94 / MGA zone 55 28355
GDA94 MGA56 GDA94 / MGA zone 56 28356
AGD66 TMAMG54 AGD66 / Australian Map Grid zone 54 20254
AGD66 TMAMG55 AGD66 / Australian Map Grid zone 55 20255
AGD66 TMAMG56 AGD66 / Australian Map Grid zone 56 20256
AGD66 GEODETIC AGD66 / Longitude/Latitude 4202
GDA94 VICGRID94 Victoria Grid 1994 3111
GDA94 NSWLAM94 New South Wales Lambert 3308
GDA94 L2SAUST South Australia Lambert 3107
GDA94 L2DARWIN Darwin Lambert
GDA94 L2KIMBER Kimberley Lambert
GDA94 L2CPYORK Cape York Lambert
GDA94 L2SIMPSN Simpson Desert Lambert
GDA94 L2NAUST Top End Lambert
GDA94 L2NQLD North Queensland Lambert
GDA94 L2PILBRA Pilbara Lambert
GDA94 L2MWAUST Middle West Western Australia Lambert
GDA94 L2GREGRY Gregory Lambert
GDA94 L2FLBDRS Flanders Range Lambert
GDA94 L2REDCEN Red Center Lambert
GDA94 L2EGDSRT Eastern Grand Desert Lambert
GDA94 L2WGDSRT Western Grand Desert Lambert
Belgium BELG72 LM2BELG72 Belgian Lambert 72 31370
ETRS89 LM2BELG2005 Belgian Lambert 2005 3447
ETRS89 LM2BELG2008 Belgian Lambert 2008 3812
Bulgaria PULKOBUL GK4 Pulkovo 1942(58) / Gauss-Krüger zone 4 3334
PULKOBUL GK5 Pulkovo 1942(58) / Gauss-Krüger zone 5 3335
Canada See USA
Finland KKJ TMFIN3 KKJ / Finland Uniform Coordinate System 2393
KKJ TMFIN2 KKJ / Finland Zone 2 2392
France NTF LM1FRA1D France Lambert I 27571
NTF LM1FRA2D France Lambert II 27572
NTF LM1FRA3D France Lambert III 27573
NTF LM2FRANC France Lambert II étendu 27572
RGF93 LMFRAN93 France Lambert 93 2154
RGF93 LMCC42Z1 Projection conique conforme Zone 1 3942
RGF93 LMCC43Z2 Projection conique conforme Zone 2 3943
RGF93 LMCC44Z3 Projection conique conforme Zone 3 3944
RGF93 LMCC45Z4 Projection conique conforme Zone 4 3945
RGF93 LMCC46Z5 Projection conique conforme Zone 5 3946
RGF93 LMCC47Z6 Projection conique conforme Zone 6 3947
RGF93 LMCC48Z7 Projection conique conforme Zone 7 3948
RGF93 LMCC49Z8 Projection conique conforme Zone 8 3948
RGF93 LMCC50Z9 Projection conique conforme Zone 9 3950
RGF93 GEOPORTALFXX Géoportail France Métropolitaine
WGS84 LMFRAVFR VFR France chart (CartaBossy)
France (Iles Amsterdam et Saint-Paul) RGTAAF07 GEOPORTALASP Géoportail Amsterdam et Saint-Paul
France (Corse) NTF LM1FRA4D France Lambert IV 27574
France (Ile Crozet) WGS84 GEOPORTALCRZ Géoportail Crozet
France (Guadeloupe) RRAF GEOPORTALANF Géoportail Antilles Françaises
GUAD48 NUTM20 Guadeloupe St Anne UTM zone 20 2970
France (Guyane) RGFG95 GEOPORTALGUF Géoportail Guyane Française
RGFG95 NUTM21 Guyane UTM zone 21 3313
RGFG95 NUTM22 Guyane UTM zone 22 2972
CSG67 NUTM21 Guyane CSG67 UTM zone 21 3312
CSG67 NUTM22 Guyane CSG67 UTM zone 22 2971
France (Iles Kerguelen) RGTAAF07 GEOPORTALKER Géoportail Kerguelen
France (Martinique) RRAF GEOPORTALANF Géoportail Antilles Françaises
MART38 NUTM20 Fort Desaix 1938 / UTM zone 20 North 2973
France (Mayotte) RGM04 GEOPORTALMYT Géoportail Mayotte
RGM04 SUTM38 Réseau Géodésique de Mayotte 2004 / UTM zone 38 Sud
MCBN50 SUTM38 Mayotte Combani 1950 / UTM zone 38 Sud 2980
France (Nouvelle Calédonie) RGNC GEOPORTALNCL Géoportail Nouvelle Calédonie
RGNC LAMBERT NC Lambert Nouvelle Calédonie 3163
France (Polynésie Française) RGPF GEOPORTALPYF Géoportail Polynésie Française
France (Réunion) RGR92 GEOPORTALREU Géoportail Réunion
REUN47 GLABREUN Réunion Gauss Laborde 3727
RGR92 SUTM40 Réseau Géodésique de la Réunion / UTM zone 40 Sud 2975
France (Saint-Barthélémy) RRAF GEOPORTALANF Géoportail Antilles Françaises
STMART NUTM20 Guadeloupe Fort Marigot UTM zone 20 2969
France (Saint-Martin) RRAF GEOPORTALANF Géoportail Antilles Françaises
STMART NUTM20 Guadeloupe Fort Marigot UTM zone 20 2969
France (Saint-Pierre et Miquelon) RGSPM06 GEOPORTALSPM Géoportail Saint-Pierre et Miquelon
France (Wallis et Futuna) WGS84 GEOPORTALWLF Géoportail Wallis et Futuna
Georgia PULKOGEO GK7 Pulkovo / Gauss Krüger zone 7 28407
Germany POTSDAM TMGER3 POTSDAM / Gauss-Krüger zone 3 3396
POTSDAM TMGER4 POTSDAM / Gauss-Krüger zone 4 3397
Great-Britain OSGB36 TMOSGB OSGB 1936 27700
Iceland ISN93 LMICEL93 ISN93 / Lambert 1993 3057
India KALIANPR LM1IND4A Kalianpur 1880 / India zone IV 24374
Ireland TM65 TMOSIRL TM65 / Irish Grid 29902
Italy ED50 NUTM32 ED50 / UTM zone 32 North 23032
ED50 NUTM33 ED50 / UTM zone 33 North 23033
MONTEMAR TMBOAGA1 Gauss-Boaga zone West 3003
MONTEMAR TMBOAGA2 Gauss-Boaga zone East 3004
MONTROME TMBOAG1R Gauss-Boaga zone West 3003
MONTROME TMBOAG2R Gauss-Boaga zone East 3004
Japan JGD2000 L2JAPAN Japanese Geodetic Datum 2000 / Lambert
Lithuania LKS94 LITHUANIATM LKS94 / Lithuania Transverse Mercator 3346
Luxembourg LURES LUREF Luxembourg 1930 / Gauss 2169
Madeira POS36 NUTM28 Porto Santo 1936 / UTM zone 28 North 2191
Mexico NAD27MEXIC NUTM14 NAD27 / UTM zone 14 North 26714
Morocco MERCHICH LM1MORND Merchich / Lambert Morocco North 26191
MERCHICH LM1MORSD Merchich / Lambert Morocco South 26192
New Zealand NZGD1949 NZMG NZGD49 / NZ Map Grid 27200
NZGD2000 NZTM NZGD2000 / NZ Transverse Mercator 2193
Poland ETRS89 PUWG1992 Polish National System 1992 2180
Portugal ETRS89 PT-TM06 ETRS89 / TM06 3763
LISBON TMLX LISBON / Gauss-Krüger 20791
LISBON TMLXMIL LISBON / Gauss-Krüger Military 20790
MELRICA TM73 MELRICA / Gauss-Krüger 73 27493
ED50-PT NUTM29 ED50 / UTM zone 29 North 23029
Slovenia D96 TMSLO Slovenia 1996 / Slovene National Grid 3794
Spain ED50-SP NUTM29 ED50 / UTM zone 29 North 23029
ED50-SP NUTM30 ED50 / UTM zone 30 North 23030
ED50-SP NUTM31 ED50 / UTM zone 31 North 23031
Switzerland BERNNEW SWISSNEW Swiss Grid (CH1903) 21781
The Netherlands RD DUTCHNEW Dutch New (Amersfoort) 28992
USA / Canada NAD27 NUTM11 NAD27 / UTM zone 11 North 26711
NAD27 NUTM12 NAD27 / UTM zone 12 North 26712
NAD27 ALTEALE NAD27 / California Albers Equal Area 3309
NAD83 GEODETIC NAD83 / Longitude/Latitude 4269
NAD83 NUTM7 NAD83 / UTM zone 7 North 26907
NAD83 NUTM8 NAD83 / UTM zone 8 North 26908
NAD83 NUTM9 NAD83 / UTM zone 9 North 26909
NAD83 NUTM10 NAD83 / UTM zone 10 North 26910
NAD83 NUTM11 NAD83 / UTM zone 11 North 26911
NAD83 NUTM12 NAD83 / UTM zone 12 North 26912
NAD83 NUTM13 NAD83 / UTM zone 13 North 26913
NAD83 NUTM14 NAD83 / UTM zone 14 North 26914
NAD83 NUTM15 NAD83 / UTM zone 15 North 26915
NAD83 NUTM16 NAD83 / UTM zone 16 North 26916
NAD83 NUTM17 NAD83 / UTM zone 17 North 26917
NAD83 NUTM18 NAD83 / UTM zone 18 North 26918
NAD83 NUTM19 NAD83 / UTM zone 19 North 26919
NAD83 NUTM20 NAD83 / UTM zone 20 North 26920
NAD83 NUTM21 NAD83 / UTM zone 21 North 26921
NAD83 NUTM22 NAD83 / UTM zone 22 North 26922
former Yougoslavia MGIBESS GK6BALK MGI Bessel / Gauss-Krüger Balkans zone 6 3908

Adding datums and projections

If you want to add your own projection, you can do so using the method explained below. But in order to extend the ttMaps projection database, I prefer that you send me:

If the file is big, drop it on a file sharing site like, and send me the link.

Changing the sqlite database

If you are familiar with databases and map projections, you can edit yourself the projections database of ttMaps. The datums and projections are stored in a sqlite database. The file name is proj.db and it is stored in the data subdirectory of ttMaps.

The easiest way to add map projections is to convert the database into SQL instructions:

sqlite3 proj.db ".dump" >proj.sql

Then, after modifying the file proj.sql, recreate the file proj.db:

rm proj.db
sqlite3 proj.db <proj.sql

The database is composed of two tables. The table param contains the projection parameters, and the table proj contains the names of datums and projections used in ECW files with a link to a row of the table param.

Table param

Field Type Comment
id_proj integer primary key Table index
lon_min real Minimal longitude of validity zone
lon_max real Maximal longitude of validity zone
lat_min real Minimal latitude of validity zone
lat_max real Maximal latitude of validity zone
parameters varchar(255) unique PROJ.4 parameters string
unit char Unit : 'm' (meters) or 'd' (degrees)
comments varchar(80) Comments

Table proj

Field Type Comment
datum varchar(12) ErMapper name of the datum
projection varchar(13) ErMapper name of the projection
proj_id integer Index toward table param

Last modification : 08/01/2013