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Adobe® Supplement to the ISO 32000
Examples of WKT description strings appear at the end of the next section, beginning on
Projected Coordinate System Dictionary
A projected coordinate system (PROJCS), which includes an embedded GEOGCS, specifies the algorithms
and associated parameters used to transform points between geographic coordinates and a
two-dimensional (projected) coordinate system. Any transformation between a three-dimensional curved
geographic coordinate system and a two-dimensional coordinate system introduces distortions. For small
areas, this distortion may be small enough to allow direct mapping between geographic coordinates and
PDF object coordinates without requiring the use of a projected coordinate system.
The projected coordinate system can be described in either or both of two well-established standards: as a
numeric EPSG reference code, or as a Well KnownText (WKT) string, which contains a description of
algorithms and parameters needed for transformations.
The EPSG reference codes are described in a database available through www.epsg.org, as administered
by the International Association of Oil and Gas Producers (OGP). Well Known Text is specified in document
01-009, OpenGIS Implementation Specification: Coordinate Transformation Services, of the Open Geospatial
Consortium. (See Bibliography.) See implementation note E-9,
Table 8.111c lists the entries in a projected coordinate system dictionary. A projected coordinate system
dictionary may be a value of the
page
50.
KEY
Type
EPSG
WKT
Either an
implementation note E-20,
Example: A WKT describing a geographic coordinate system
An example of WKT description of a geographic coordinate system, formatted for readability. The EPSG
code equivalent to the GCS_North_American_1983 geographic coordinate system is 4269.
GEOGCS["GCS_North_American_1983",
DATUM["D_North_American_1983",
SPHEROID["GRS_1980",6378137.0,298.257222101]
],
PRIMEM["Greenwich",0.0],
UNIT["Degree",0.0174532925199433]
]
GCS
TABLE 8.111c Entries in a projected coordinate system dictionary
TYPE
name
integer
ASCII string
code or a
string is required in the projected coordinate system dictionary. (See
EPSG
WKT
page
or the
entry of a geospatial measure dictionary, Table 8.111a on
DCS
VALUE
(Required; ExtensionLevel 3) The type of PDF object that this
dictionary describes; shall be
system dictionary.
(Optional; ExtensionLevel 3) An EPSG reference code specifying the
projected coordinate system.
(Optional; ExtensionLevel 3) A string of Well Known Text describing
the projected coordinate system.
See implementation note E-8,
132.)
Interactive Features (Chapter 8 in PDF Reference)
8.8.1 Geospatial Features
page
131.
for a projected coordinate
PROJCS
page
131.
52
page
52.
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