| Long name |
NTF Strategi |
| Short name |
NTFS |
| File extension(s) |
.ntf |
Strategi Data(NTF v2.0 level 3) are supported by the GDB library
for import and view. It is supplied by national cover, selected
layer, regional cover, or 50km by 50km tiles.
Strategi is defined as a limited "link and node" structure. It contains
points, lines and nodes. Nodes have pointers to lines (links) that join
at the node but there is no explicit topology within the data. Similarly,
there are lines (links) that enclose an area containing a point (seed), and
again there is no explicit topology between the lines (links) and point(seed).
Some points (seeds) are not contained within areas enclosed by lines (links).
Four vector layers may be used to display its three data set:
- point
- line
- node
- text
Structure of features
The structure of each different feature is as follows:
- Point Feature:
- a Point Record [POINTREC] 15
- a Geometry Record [GEOMETRY1] 21
- an associated Attribute Record [ATTREC] 14, which contains
a measurement for variable sized symbols.
- Line Feature:
- a Line Record [LINEREC] 23
- a Geometry Record [GEOMETRY1] 21,and maybe one or more
continuation Records[CONTREC] 00 to extend the Geometry Record.
- an associated Attribute Record [ATTREC] 14
- Node Feature:
- a Node Record [NODEREC] 16,and maybe one or more
continuation Records[NODECONT] 00 to extend the Node Record
- a Geometry Record [GEOMETRY1] 21
- a Point Record [POINTREC] 15
- an associated Attribute Record [ATTREC] 14
- Text Feature:
- a Text Record [TEXTREC] 43
- a Text Position Record [TEXTPOS] 44
- a Text Position Record [TEXTREP] 45
- a Geometry Record [GEOMETRY1] 21
- an associated Attribute Record [ATTREC] 14
Coordinate referencing system
Coordinate values and the number of coordinate pairs in a
feature are transferred in the [GEOMETRY1] NTF record.
All coordinates within the data are expressed as strings of five
numeric characters. Leading zeros are present to complete the five characters.
All coordinates are measured from the local origin, which is the
south-west corner of the 50 km by 50 km square.
To convert coordinate data to full National Grid coordinates, add
the coordinates of the feature to those of the south-west corner
of the 50 km by 50 km square. The south-west corner coordinates are contained
within the {X_ORIG} and {Y_ORIG}fields of the Section Header Record [SECHREC].
See UK National Transfer Format (NTF)
for information on georeferencing.