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ENVIStandardRasterSpatialRef::Hydrate

ENVIStandardRasterSpatialRef::Hydrate

Use the Hydrate static function method to create the object from its dehydrated form. The dehydrated form consists of a hash containing the object’s properties and values. The Hydrate and Dehydrate methods let you store the object state in memory and restore it later.

Representing an object as a hash is necessary for running ENVI analytics with the ENVI Task Engine and the ENVI Services Engine.

See the ENVIHydrate function if you are creating a general IDL routine that will restore multiple object types.

Example


; Start the application
e = ENVI(/HEADLESS)
 
; Create a custom spatial reference object
spatialRef1 = ENVIStandardRasterSpatialRef( $
  COORD_SYS_CODE=2231, /PROJCS, $
  PIXEL_SIZE=[9.186D,9.186D], TIE_POINT_PIXEL=[0.0D,0.0D], $
  TIE_POINT_MAP=[3075299.7946D,1246937.9905D])
 
; Retrieve the dehydrated hash
dehydratedForm = spatialRef1.Dehydrate()
 
; Restore the object
newSpatialRef = ENVIStandardRasterSpatialRef.Hydrate(dehydratedForm)
Print, newSpatialRef, /IMPLIED_PRINT

Syntax


Result = ENVIStandardRasterSpatialRef.Hydrate(DehydratedForm, ERROR=value)

Return Value


The result is a reference to a new object instance of the spatial reference.

Arguments


DehydratedForm

Key

Description

factory

Required. A string value of StandardRasterSpatialRef indicating what object type the hash represents.

coord_sys_code

An integer indicating the geographic or projected coordinate system code to use. coord_sys_code and coord_sys_str are mutually exclusive.

Example:

"coord_sys_code" : 20354

coord_sys_str

A string indicating the geographic or projected coordinate system string. The coord_sys_code and coord_sys_str keys are mutually exclusive.

Example:

"coord_sys_str" : 
"PROJCS["AGD_1984_AMG_Zone_54",
GEOGCS["GCS_Australian_1984",
DATUM["D_Australian_1984",
SPHEROID["Australian",6378160.0,298.25]],
PRIMEM["Greenwich",0.0],
UNIT["Degree",0.0174532925199433]],
PROJECTION["Transverse_Mercator"],
PARAMETER["False_Easting",500000.0],
PARAMETER["False_Northing",10000000.0],
PARAMETER["Central_Meridian",141.0],
PARAMETER["Scale_Factor",0.9996],
PARAMETER["Latitude_Of_Origin",0.0],
UNIT["Meter",1.0]]"

pixel_size

Required. A two-element double-precision array with the [x,y] pixel size in the same units as the associated coordinate system. Example:

"pixel_size" : [30.0, 30.0]

rotation

A double-precision floating-point value indicating the rotation of the image, degrees clockwise from North. Example:

"rotation" : 2.0

tie_point_pixel

Required. A two-element double-precision array with the pixel coordinates of the tie point. If you do not set this key, the default pixel coordinates are [0,0]. Example:

"tie_point_pixel" : [0,0]

tie_point_map

Required. A two-element double-precision array with the map coordinates of the tie_point_pixel location, as follows:

[mapX, mapY]

The coordinates must be in the same units (degrees, meters, feet, etc.) as the associated coordinate system. Example:

"tie_point_map" : [257017.6, 7831362.4]

Keywords


ERROR

Set this keyword to a named variable that will contain any error message issued during execution of this routine. If no error occurs, the ERROR variable will be set to a null string (''). If an error occurs and the routine is a function, then the function result will be undefined.

When this keyword is not set and an error occurs, ENVI returns to the caller and execution halts. In this case, the error message is contained within !ERROR_STATE and can be caught using IDL's CATCH routine. See IDL Help for more information on !ERROR_STATE and CATCH.

See Manage Errors for more information on error handling in ENVI programming.

Version History


ENVI 5.4

Introduced

API Version


3.3

See Also


ENVIStandardRasterSpatialRef, ENVIStandardRasterSpatialRef::Dehydrate, ENVIHydratable, ENVIHydrate



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