Name

National Transfer Format Files (NTF)

Synopsis

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.

File listing

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 ...

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