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SpatialReference

In diesem Thema

  1. Zusammenfassung
  2. Diskussion
  3. Syntax
  4. Eigenschaften
  5. Methodenübersicht
  6. Methoden
  7. Codebeispiel
Verwandte Themen
  1. Classes in Python
  2. Verwenden der Raumbezugsklasse

Zusammenfassung

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.

Diskussion

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

XY-, Z- und M-Ausdehnungen sind nicht mit Raumbezugsdomänen identisch. Die XY-, Z- und M-Domänen in einem Raumbezug definieren den gültigen Bereich von Koordinatenwerten, die in einer Feature-Class gespeichert werden können. Die Feature-Class-Ausdehnungen spiegeln den tatsächlichen Bereich von Koordinatenwerten wider, die in der Feature-Class enthalten sind. Diese Ausdehnungen dürfen nicht größer sein als die Domänen.

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

Hinweis:

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.

Syntax

 SpatialReference ({item}, {vcs}, {text})
ParameterErläuterungDatentyp
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

Eigenschaften

EigenschaftErläuterungDatentyp
GCS
(Schreibgeschützt)

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
(Schreibgeschützt)

The extent of the measure domain.

String
MFalseOriginAndUnits
(Schreibgeschützt)

The measure false origin and units.

String
MResolution
(Lesen und schreiben)

The measure resolution.

Double
MTolerance
(Lesen und schreiben)

The measure tolerance.

Double
VCS
(Schreibgeschützt)

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
(Lesen und schreiben)

The xy resolution.

Double
XYTolerance
(Lesen und schreiben)

The xy tolerance.

Double
ZDomain
(Schreibgeschützt)

The extent of the z domain.

String
ZFalseOriginAndUnits
(Schreibgeschützt)

The z false origin and units.

String
ZResolution
(Lesen und schreiben)

The z resolution property.

Double
ZTolerance
(Lesen und schreiben)

The z-tolerance property.

Double
abbreviation
(Lesen und schreiben)

The abbreviated name of the spatial reference.

String
alias
(Lesen und schreiben)

The alias of the spatial reference.

String
domain
(Schreibgeschützt)

The extent of the xy domain.

String
factoryCode
(Lesen und schreiben)

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

Integer
falseOriginAndUnits
(Schreibgeschützt)

The false origin and units.

String
hasMPrecision
(Schreibgeschützt)

Indicates whether m-value precision information has been defined.

Boolean
hasXYPrecision
(Schreibgeschützt)

Indicates whether xy precision information has been defined.

Boolean
hasZPrecision
(Schreibgeschützt)

Indicates whether z-value precision information has been defined.

Boolean
isHighPrecision
(Lesen und schreiben)

Indicates whether the spatial reference has high precision set.

Boolean
name
(Lesen und schreiben)

The name of the spatial reference.

String
remarks
(Lesen und schreiben)

The comment string of the spatial reference.

String
type
(Lesen und schreiben)

The type of the spatial reference.

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

The usage notes.

String
PCSCode
(Lesen und schreiben)

The projected coordinate system code.1

Integer
PCSName
(Lesen und schreiben)

The projected coordinate system name.1

String
azimuth
(Lesen und schreiben)

The azimuth of a projected coordinate system.1

Double
centralMeridian
(Lesen und schreiben)

The central meridian of a projected coordinate system.1

Double
centralMeridianInDegrees
(Lesen und schreiben)

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

Double
centralParallel
(Lesen und schreiben)

The central parallel of a projected coordinate system.1

Double
classification
(Schreibgeschützt)

The classification of a map projection.1

String
falseEasting
(Lesen und schreiben)

The false easting of a projected coordinate system.1

Double
falseNorthing
(Lesen und schreiben)

The false northing of a projected coordinate system.1

Double
latitudeOf1st
(Lesen und schreiben)

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

Double
latitudeOf2nd
(Lesen und schreiben)

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

Double
latitudeOfOrigin
(Lesen und schreiben)

The latitude of origin of a projected coordinate system.1

Double
linearUnitCode
(Lesen und schreiben)

The linear unit code.1

Integer
linearUnitName
(Lesen und schreiben)

The linear unit name.1

String
longitude
(Lesen und schreiben)

The longitude value of this prime meridian.1

Double
longitudeOf1st
(Lesen und schreiben)

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

Double
longitudeOf2nd
(Lesen und schreiben)

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

Double
longitudeOfOrigin
(Lesen und schreiben)

The longitude of origin of a projected coordinate system.1

Double
metersPerUnit
(Schreibgeschützt)

The meters per linear unit.1

Double
projectionCode
(Lesen und schreiben)

The projection code.1

Integer
projectionName
(Lesen und schreiben)

The projection name.1

String
scaleFactor
(Lesen und schreiben)

The scale factor of a projected coordinate system.1

Double
standardParallel1
(Lesen und schreiben)

The first parallel of a projected coordinate system.1

Double
standardParallel2
(Lesen und schreiben)

The second parallel of a projected coordinate system.1

Double
GCSCode
(Lesen und schreiben)

Der Code des geographischen Koordinatensystems.2

Integer
GCSName
(Lesen und schreiben)

Der Name des geographischen Koordinatensystems.2

String
angularUnitCode
(Lesen und schreiben)

Der Code der Winkeleinheit.2

Integer
angularUnitName
(Lesen und schreiben)

Der Name der Winkeleinheit.2

String
datumCode
(Lesen und schreiben)

Der Code des Datums.2

Integer
datumName
(Lesen und schreiben)

Der Name des Datums.2

String
Abplattung
(Lesen und schreiben)

Das Abflachungsverhältnis dieses Sphäroids.2

Double
Längengrad
(Lesen und schreiben)

Der Längengradwert für diesen Nullmeridian.2

Double
primeMeridianCode
(Lesen und schreiben)

Der Code des Nullmeridians.2

Integer
primeMeridianName
(Lesen und schreiben)

Der Name des Nullmeridians.2

String
radiansPerUnit
(Schreibgeschützt)

Radianten pro Winkeleinheit.2

Double
semiMajorAxis
(Lesen und schreiben)

Die Länge der großen Hauptachse dieses Sphäroids.2

Double
semiMinorAxis
(Lesen und schreiben)

Die Länge der kleinen Hauptachse dieses Sphäroids.2

Double
spheroidCode
(Lesen und schreiben)

Der Code des Sphäroids.2

Integer
spheroidName
(Lesen und schreiben)

Der Name des Sphäroids.2

String

Methodenübersicht

MethodeErläuterung
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.

Methoden

create ()
createFromFile (prj_file)
ParameterErläuterungDatentyp
prj_file

The projection file used to populate the SpatialReference object.

String
exportToString ()
Rückgabewert
DatentypErläuterung
String

The WKT string representation of the object. 

loadFromString (string)
ParameterErläuterungDatentyp
string

The WKT string representation of the object.

String
setDomain (x_min, x_max, y_min, y_max)
ParameterErläuterungDatentyp
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)
ParameterErläuterungDatentyp
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)
ParameterErläuterungDatentyp
m_min

The minimum m-value.

Double
m_max

The maximum m-value.

Double
setMFalseOriginAndUnits (false_m, m_units)
ParameterErläuterungDatentyp
false_m

The false m-value.

Double
m_units

The m units.

Double
setZDomain (z_min, z_max)
ParameterErläuterungDatentyp
z_min

The minimum z-value.

Double
z_max

The maximum z-value.

Double
setZFalseOriginAndUnits (false_z, z_units)
ParameterErläuterungDatentyp
false_z

The false z-value.

Double
z_units

The false z units.

Double

Codebeispiel

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))

Verwandte Themen

  • Classes in Python
  • Verwenden der Raumbezugsklasse

Feedback zu diesem Thema?

In diesem Thema
  1. Zusammenfassung
  2. Diskussion
  3. Syntax
  4. Eigenschaften
  5. Methodenübersicht
  6. Methoden
  7. Codebeispiel
Verwandte Themen
  1. Classes in Python
  2. Verwenden der Raumbezugsklasse