File listing

National Transfer Format Files (NTF)

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NTF files are mostly used by the U.K. Ordnance Survey (OS). For more on the Ordnance Survey, see their web site at http://www.ordnancesurvey.co.uk.

NTF files have an NTF extension.

Data access/connection method

• NTF access requires OGR.

• The path to the NTF file is required in the CONNECTION string. It may be relative to the SHAPEPATH setting in the map file or the full path.

• The CONNECTION must also include a layer number (as per the layer number from ogrinfo, but minus one).

ogrinfo examples

Here's an example that uses ogrinfo on an NTF file to retrieve layer numbers:

     > ogrinfo llcontours.ntf     ERROR 4: NTF Driver doesn't support update.     Had to open data source read-only.     INFO: Open of 'llcontours.ntf'     using driver 'UK .NTF' successful.     1: LANDLINE_POINT (Point)     2: LANDLINE_LINE (Line String)     3: LANDLINE_NAME (Point)     4: FEATURE_CLASSES (None) 

For the LANDLINE_LINE layer, the ogrinfo layer number is 2; however, when referring to this layer in a map file connection, the layer number is 1.

Here's an example that uses ogrinfo to examine the structure of an NTF layer:

     > ogrinfo llcontours.ntf LANDLINE_LINE     ERROR 4: NTF Driver doesn't support update.     Had to open data source read-only.     INFO: Open of 'llcontours.ntf'     using driver 'UK .NTF' successful.           Layer name: LANDLINE_LINE     Geometry: Line String     Feature Count: 491     Extent: (279000.000000, 187000.000000) - (280000.000000, 188000.000000)     Layer SRS WKT:     PROJCS["OSGB 1936 / British National Grid",               GEOGCS["OSGB 1936",             DATUM["OSGB_1936",                 SPHEROID["Airy 1830",6377563.396,299.3249646,                     AUTHORITY["EPSG","7001"]],                 AUTHORITY["EPSG","6277"]],             PRIMEM["Greenwich",0,                 AUTHORITY["EPSG","8901"]],             UNIT["degree",0.0174532925199433],             AUTHORITY["EPSG","4277"]],         PROJECTION["Transverse_Mercator"],         PARAMETER["latitude_of_origin",49],         PARAMETER["central_meridian",-2],         PARAMETER["scale_factor",0.999601272],         PARAMETER["false_easting",400000],         PARAMETER["false_northing",-100000],         UNIT["metre",1,             AUTHORITY["EPSG","9001"]],         AUTHORITY["EPSG","27700"]]     LINE_ID: Integer (6.0)     FEAT_CODE: String (4.0)     ... 

Map file example

     LAYER       NAME ntf_uk       TYPE LINE       CONNECTIONTYPE OGR       CONNECTION "./ntf/llcontours.ntf,1"       STATUS DEFAULT       CLASS         NAME "Contours"         COLOR 0 150 200       END     END