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.
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.
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 |
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 http://dl.free.fr, and send me the link.
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