Skip to Content
Web Mapping Illustrated
book

Web Mapping Illustrated

by Tyler Mitchell
June 2005
Beginner to intermediate
372 pages
10h 1m
English
O'Reilly Media, Inc.
Content preview from Web Mapping Illustrated

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 ...
Become an O’Reilly member and get unlimited access to this title plus top books and audiobooks from O’Reilly and nearly 200 top publishers, thousands of courses curated by job role, 150+ live events each month,
and much more.
Start your free trial

You might also like

Flask Web Development, 2nd Edition

Flask Web Development, 2nd Edition

Miguel Grinberg

Publisher Resources

ISBN: 0596008651Supplemental ContentErrata Page