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SpatialReference

Dans cette rubrique

  1. Synthèse
  2. Discussion
  3. Syntaxe
  4. Propriétés
  5. Vue d’ensemble des méthodes
  6. Méthodes
  7. Exemple de code
Rubriques connexes
  1. Classes in Python
  2. Utilisation de la classe de références spatiales

Synthèse

Each part of the spatial reference has a number of properties (especially the coordinate system) that defines what map projection options are used to define horizontal coordinates.

Discussion

A SpatialReference object can also be accessed from existing datasets using the Describe spatialReference property.

dataset = "c:/data/landbase.gdb/Wetlands"
spatial_ref = arcpy.Describe(dataset).spatialReference

Les étendues XY, Z et M ne correspondent pas aux domaines de référence spatiale. Les domaines XY, Z et M d'une référence spatiale définissent la plage valide de valeurs de coordonnées pouvant être stockées dans une classe d'entités. Les étendues de la classe d’entités reflètent la plage réelle des valeurs de coordonnées présentes dans la classe d’entités. Ces étendues ne peuvent pas être plus importantes que les domaines.

The SpatialReference object supports equal (==) and not equal (!=) operators for comparing spatial references.

Remarque :

The spatial reference properties available depend on the coordinate system used. In the properties list below, those properties that are only available with a projected coordinate system are denoted with a 1; properties only available with a geographic coordinate system are denoted with a 2.

Because a projected coordinate system is based on a geographic coordinate system, projected coordinate system properties can be accessed from a geographic coordinate system using the GCS property.

Syntaxe

 SpatialReference ({item}, {vcs}, {text})
ParamètreExplicationType de données
item

The horizontal coordinate system used to create the SpatialReference. The coordinate system can be set using a projection file, name, or factory code.

  • Using the display name of the coordinate system
    sr = arcpy.SpatialReference("Sinusoidal (world)")
  • Using the canonical name of the coordinate system
    sr = arcpy.SpatialReference("World_Sinusoidal")
  • Using a coordinate system's factory code (or authority code or WKID)
    # The factory code of 32145 represents: 
# NAD 1983 StatePlane Vermont FIPS 4400 (Meters)

sr = arcpy.SpatialReference(32145)
  • Using a projection file (.prj)
    sr = arcpy.SpatialReference("c:/coordsystems/NAD 1983.prj")

For more information about coordinate system names and factory codes, see the geographic_coordinate_systems.pdf and projected_coordinate_systems.pdf files.

For more information, see Using the spatial reference class.

Variant
vcs

The vertical coordinate system (VCS). The VCS defines information about the z-coordinates and can be set using a name or factory code. See the following examples:

  • Using a name
    sr = arcpy.SpatialReference("Hawaii Albers Equal Area Conic", "MSL Height")
  • Using a factory code
    # Spatial Reference factory code of 32145 is : NAD 1983 StatePlane Vermont FIPS 4400 (Meters)
# Spatial Reference factory code of 5714 is : Mean Sea Level (Height)

sr = arcpy.SpatialReference(32145, 5714)
Variant
text

A well-known text (WKT) string that can be used to define a horizontal and vertical coordinate system.

  • Using a WKT string with a horizontal coordinate system
    # String below is the WKT for the 
# Geographic Coordinate system "WGS 1984" (factory code=4326)
wkt = """
GEOGCS['GCS_WGS_1984',DATUM['D_WGS_1984',SPHEROID['WGS_1984',6378137.0,298.257223563]],
PRIMEM['Greenwich',0.0],UNIT['Degree',0.0174532925199433]];
-400 -400 1000000000;-100000 10000;-100000 10000;8.98315284119522E-09;
0.001;0.001;IsHighPrecision
"""

sr = arcpy.SpatialReference(text=wkt)
  • Using a WKT string with a horizontal and vertical coordinate system. Note that the vcs argument is not used, and the vertical coordinate system is defined in the VERTCS section of the WKT.
    # The following string is the WKT for the 
# Geographic Coordinate system "WGS 1984" (factory code=4326)
wkt = """
GEOGCS['GCS_WGS_1984',DATUM['D_WGS_1984',SPHEROID['WGS_1984',6378137.0,298.257223563]],
PRIMEM['Greenwich',0.0],UNIT['Degree',0.0174532925199433]],
VERTCS['WGS_1984',DATUM['D_WGS_1984',SPHEROID['WGS_1984',6378137.0,298.257223563]],
PARAMETER['Vertical_Shift',0.0],PARAMETER['Direction',1.0],UNIT['Meter',1.0]];
-400 -400 1000000000;-100000 10000;-100000 10000;8.98315284119522E-09;
0.001;0.001;IsHighPrecision
"""

sr = arcpy.SpatialReference(text=wkt)
String

Propriétés

PropriétéExplicationType de données
GCS
(Lecture seule)

A projected coordinate system returns a SpatialReference object for the geographic coordinate system it is based on. A geographic coordinate system returns the same SpatialReference.

SpatialReference
MDomain
(Lecture seule)

The extent of the measure domain.

String
MFalseOriginAndUnits
(Lecture seule)

The measure false origin and units.

String
MResolution
(Lecture et écriture)

The measure resolution.

Double
MTolerance
(Lecture et écriture)

The measure tolerance.

Double
VCS
(Lecture seule)

If the coordinate system has a vertical coordinate system, it returns a VCS object for the vertical coordinate system it is based on.

Object
XYResolution
(Lecture et écriture)

The xy resolution.

Double
XYTolerance
(Lecture et écriture)

The xy tolerance.

Double
ZDomain
(Lecture seule)

The extent of the z domain.

String
ZFalseOriginAndUnits
(Lecture seule)

The z false origin and units.

String
ZResolution
(Lecture et écriture)

The z resolution property.

Double
ZTolerance
(Lecture et écriture)

The z-tolerance property.

Double
abbreviation
(Lecture et écriture)

The abbreviated name of the spatial reference.

String
alias
(Lecture et écriture)

The alias of the spatial reference.

String
domain
(Lecture seule)

The extent of the xy domain.

String
factoryCode
(Lecture et écriture)

The factory code or well-known ID (WKID) of the spatial reference.

Integer
falseOriginAndUnits
(Lecture seule)

The false origin and units.

String
hasMPrecision
(Lecture seule)

Indicates whether m-value precision information has been defined.

Boolean
hasXYPrecision
(Lecture seule)

Indicates whether xy precision information has been defined.

Boolean
hasZPrecision
(Lecture seule)

Indicates whether z-value precision information has been defined.

Boolean
isHighPrecision
(Lecture et écriture)

Indicates whether the spatial reference has high precision set.

Boolean
name
(Lecture et écriture)

The name of the spatial reference.

String
remarks
(Lecture et écriture)

The comment string of the spatial reference.

String
type
(Lecture et écriture)

The type of the spatial reference.

  • Geographic—A geographic coordinate system.
  • Projected— A projected coordinate system.
String
usage
(Lecture seule)

The usage notes.

String
PCSCode
(Lecture et écriture)

The projected coordinate system code.1

Integer
PCSName
(Lecture et écriture)

The projected coordinate system name.1

String
azimuth
(Lecture et écriture)

The azimuth of a projected coordinate system.1

Double
centralMeridian
(Lecture et écriture)

The central meridian of a projected coordinate system.1

Double
centralMeridianInDegrees
(Lecture et écriture)

The central meridian (Lambda0) of a projected coordinate system in degrees.1

Double
centralParallel
(Lecture et écriture)

The central parallel of a projected coordinate system.1

Double
classification
(Lecture seule)

The classification of a map projection.1

String
falseEasting
(Lecture et écriture)

The false easting of a projected coordinate system.1

Double
falseNorthing
(Lecture et écriture)

The false northing of a projected coordinate system.1

Double
latitudeOf1st
(Lecture et écriture)

The latitude of the first point of a projected coordinate system.1

Double
latitudeOf2nd
(Lecture et écriture)

The latitude of the second point of a projected coordinate system.1

Double
latitudeOfOrigin
(Lecture et écriture)

The latitude of origin of a projected coordinate system.1

Double
linearUnitCode
(Lecture et écriture)

The linear unit code.1

Integer
linearUnitName
(Lecture et écriture)

The linear unit name.1

String
longitude
(Lecture et écriture)

The longitude value of this prime meridian.1

Double
longitudeOf1st
(Lecture et écriture)

The longitude of the first point of a projected coordinate system.1

Double
longitudeOf2nd
(Lecture et écriture)

The longitude of the second point of a projected coordinate system.1

Double
longitudeOfOrigin
(Lecture et écriture)

The longitude of origin of a projected coordinate system.1

Double
metersPerUnit
(Lecture seule)

The meters per linear unit.1

Double
projectionCode
(Lecture et écriture)

The projection code.1

Integer
projectionName
(Lecture et écriture)

The projection name.1

String
scaleFactor
(Lecture et écriture)

The scale factor of a projected coordinate system.1

Double
standardParallel1
(Lecture et écriture)

The first parallel of a projected coordinate system.1

Double
standardParallel2
(Lecture et écriture)

The second parallel of a projected coordinate system.1

Double
GCSCode
(Lecture et écriture)

Code du système de coordonnées géographiques.2

Integer
GCSName
(Lecture et écriture)

Nom du système de coordonnées géographiques.2

String
angularUnitCode
(Lecture et écriture)

Code d'unité angulaire.2

Integer
angularUnitName
(Lecture et écriture)

Nom d'unité angulaire.2

String
datumCode
(Lecture et écriture)

Code du datum.2

Integer
datumName
(Lecture et écriture)

Nom du datum.2

String
flattening
(Lecture et écriture)

Coefficient d'aplatissement de cette sphéroïde.2

Double
longitude
(Lecture et écriture)

Valeur de longitude de ce méridien principal.2

Double
primeMeridianCode
(Lecture et écriture)

Code de méridien principal.2

Integer
primeMeridianName
(Lecture et écriture)

Nom du méridien principal.2

String
radiansPerUnit
(Lecture seule)

Radians par unité angulaire.2

Double
semiMajorAxis
(Lecture et écriture)

Longueur du demi-grand axe de ce sphéroïde.2

Double
semiMinorAxis
(Lecture et écriture)

Longueur du demi-petit axe de ce sphéroïde.2

Double
spheroidCode
(Lecture et écriture)

Code du sphéroïde.2

Integer
spheroidName
(Lecture et écriture)

Nom du sphéroïde.2

String

Vue d’ensemble des méthodes

MéthodeExplication
create ()

Creates the SpatialReference object using properties.

createFromFile (prj_file)

Creates the SpatialReference object from a projection file.

exportToString ()

Exports the object to its string representation.

loadFromString (string)

Defines a SpatialReference object from a WKT string.

The exportToString method can be used to export a WKT string representation of the spatial reference.

  • Using a WKT string with a horizontal coordinate system.
    # The following string is the WKT for the 
# Geographic Coordinate system "WGS 1984" (factory code=4326)
wkt = 'GEOGCS["GCS_WGS_1984",DATUM["D_WGS_1984",SPHEROID["WGS_1984",6378137.0,298.257223563]],\
              PRIMEM["Greenwich",0.0],UNIT["Degree",0.0174532925199433]];\
              -400 -400 1000000000;-100000 10000;-100000 10000;8.98315284119522E-09;\
              0.001;0.001;IsHighPrecision'

sr = arcpy.SpatialReference()
sr.loadFromString(wkt)
  • Using a WKT string with a horizontal and vertical coordinate system. Note that the vertical coordinate system is defined in the VERTCS section of the WKT.
    # The following string is the WKT for the 
# Geographic Coordinate system "WGS 1984" (factory code=4326), 
# with a vertical coordinate system "WGS 1984" (factory code=115700)

wkt = 'GEOGCS["GCS_WGS_1984",DATUM["D_WGS_1984",SPHEROID["WGS_1984",6378137.0,298.257223563]],\
              PRIMEM["Greenwich",0.0],UNIT["Degree",0.0174532925199433]],\
              VERTCS["WGS_1984",DATUM["D_WGS_1984",SPHEROID["WGS_1984",6378137.0,298.257223563]],\
              PARAMETER["Vertical_Shift",0.0],PARAMETER["Direction",1.0],UNIT["Meter",1.0]];\
              -400 -400 1000000000;-100000 10000;-100000 10000;8.98315284119522E-09;\
              0.001;0.001;IsHighPrecision'

sr = arcpy.SpatialReference()
sr.loadFromString(wkt)

setDomain (x_min, x_max, y_min, y_max)

Sets the XY domain.

setFalseOriginAndUnits (false_x, false_y, xy_units)

Sets the XY false origin and units.

setMDomain (m_min, m_max)

Sets the M domain.

setMFalseOriginAndUnits (false_m, m_units)

Sets the M false origin and units.

setZDomain (z_min, z_max)

Sets the Z domain.

setZFalseOriginAndUnits (false_z, z_units)

Sets the Z false origin and units.

Méthodes

create ()
createFromFile (prj_file)
ParamètreExplicationType de données
prj_file

The projection file used to populate the SpatialReference object.

String
exportToString ()
Valeur renvoyée
Type de donnéesExplication
String

The WKT string representation of the object. 

loadFromString (string)
ParamètreExplicationType de données
string

The WKT string representation of the object.

String
setDomain (x_min, x_max, y_min, y_max)
ParamètreExplicationType de données
x_min

The minimum x-value.

Double
x_max

The maximum x-value.

Double
y_min

The minimum y-value.

Double
y_max

The maximum y-value.

Double
setFalseOriginAndUnits (false_x, false_y, xy_units)
ParamètreExplicationType de données
false_x

The false x value.

Double
false_y

The false y value.

Double
xy_units

The xy units.

String
setMDomain (m_min, m_max)
ParamètreExplicationType de données
m_min

The minimum m-value.

Double
m_max

The maximum m-value.

Double
setMFalseOriginAndUnits (false_m, m_units)
ParamètreExplicationType de données
false_m

The false m-value.

Double
m_units

The m units.

Double
setZDomain (z_min, z_max)
ParamètreExplicationType de données
z_min

The minimum z-value.

Double
z_max

The maximum z-value.

Double
setZFalseOriginAndUnits (false_z, z_units)
ParamètreExplicationType de données
false_z

The false z-value.

Double
z_units

The false z units.

Double

Exemple de code

SpatialReference example

For each feature class in a workspace, print the name of its spatial reference.

import arcpy

# Set the workspace environment
arcpy.env.workspace = "c:/base/base.gdb"

# Get a list of the feature classes in the input folder
feature_classes = arcpy.ListFeatureClasses()

# Loop through the list
for fc in feature_classes:
    # Create the spatial reference object
    spatial_ref = arcpy.Describe(fc).spatialReference

    # If the spatial reference is unknown
    if spatial_ref.name == "Unknown":
        print("{} has an unknown spatial reference".format(fc))

    # Otherwise, print out the feature class name and spatial reference
    else:
        print("{} : {}".format(fc, spatial_ref.name))

Rubriques connexes

  • Classes in Python
  • Utilisation de la classe de références spatiales

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Dans cette rubrique
  1. Synthèse
  2. Discussion
  3. Syntaxe
  4. Propriétés
  5. Vue d’ensemble des méthodes
  6. Méthodes
  7. Exemple de code
Rubriques connexes
  1. Classes in Python
  2. Utilisation de la classe de références spatiales