JGD2011 plane rectangular zone IX
EPSG:6677 is JGD2011 / Japan Plane Rectangular CS IX, a Transverse Mercator projection in metres on the GRS80 ellipsoid of the Japanese Geodetic Datum 2011. Its central meridian is 139.833333333333° E, that is 139° 50′ E, the latitude of origin is 36° N, the scale factor is 0.9999, the false easting is 0 m and the false northing is 0 m.
The definition bundled with mapverter gives an area of use from 138.4° to 141.11° E and 29.31° to 37.98° N. Zone IX covers the Tokyo area. In mapverter's easting-northing order, the point at 139.75° E, 35.7° N is about x = −7,541 m and y = −33,280 m.
Zone, datum and axis order
A zone number alone does not identify the datum, so check whether the source says JGD2011, JGD2000 or the old Tokyo Datum. In fiscal 2025 the Geospatial Information Authority of Japan (GSI) renamed JGD2011 to JGD2024 together with a nationwide revision of elevations. It did not change the datum definition, and the horizontal values, including latitude, longitude and plane rectangular coordinates, were carried over from JGD2011. Heights were revised, and mapverter does not change heights.
In Japan's plane rectangular system X points north and Y points east, so survey tables usually list northing as X and easting as Y. EPSG:6677 itself lists northing first, while mapverter uses easting first and northing second.
How mapverter handles EPSG:6677
- A .prj is matched by its EPSG code or by its projection parameters, so ESRI-style names such as JGD_2011_Japan_Zone_9 are recognized as well. The parameters do not include the datum, so a .prj for JGD2000 zone IX is also read as EPSG:6677, while one for the old Tokyo Datum, which uses the Bessel ellipsoid, is not. mapverter matches it against its EPSG list as Tokyo / Japan Plane Rectangular CS IX (EPSG:30169), or keeps it as a custom coordinate system if the list cannot be loaded.
- Without a .prj, the Japanese interface offers EPSG:6677 first among the candidates that fit the data. Other plane rectangular zones can have similarly small or negative coordinates. The English interface does not suggest it, so search for 6677 by EPSG code in the coordinate system picker and check the result on the map.
- mapverter reads CSV columns named X and Y as easting and northing respectively. If a table follows the Japanese convention of X for northing and Y for easting, swap the two column names before converting.
- This page presets EPSG:6677 as the target for SHP and CSV output. KML, KMZ, GeoJSON and GPX always use WGS 84. No epoch or crustal-deformation correction is applied.