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ENVISubsetRaster::Hydrate

ENVISubsetRaster::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)
 
; Open an input file
file = FILEPATH('qb_boulder_msi', ROOT_DIR=e.ROOT_DIR, $
  SUBDIRECTORY = ['data'])
raster = e.OpenRaster(file)
 
; Create a spatial subset of 100 samples x 100 lines
; and a spectral subset of Band 1.
Subset = ENVISubsetRaster(Raster, SUB_RECT=[200,200,299,299], BANDS=0)
 
; Retrieve the dehydrated hash
dehydratedForm = Subset.Dehydrate()
Subset.close
 
; Restore the object
newImage = ENVISubsetRaster.Hydrate(dehydratedForm)
Print, newImage, /IMPLIED_PRINT

Syntax


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

Return Value


The result is a reference to a new object instance of this virtual raster class.

Arguments


DehydratedForm

Key

Description

factory

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

input_raster

Required. The input ENVIRaster for use in ENVI processing. Example:

"input_raster": {
   "url": "/usr/local/harris/envi/data/qb_boulder_msi",
   "factory": "URLRaster"
}

bands

A scalar integer or integer array of zero-based band indices. Example:

"bands" : [ 0, 1, 3 ]

name

A string that identifies the raster.

spatialref

An ENVIStandardRasterSpatialRef, ENVIPseudoRasterSpatialRef, or ENVIRPCRasterSpatialref hash if you want to reproject the source rasters to a common spatial reference. Example:

spatialRef: {
   "factory": "StandardRasterSpatialRef",
   "rotation": 0.00000000,
   "tie_point_pixel": [0.00000000, 0.00000000],
   "coord_sys_code": 32611,
   "pixel_size": [30.000000, 30.000000],
   "tie_point_map": [493785.00, 4899315.0]
}

sub_rect

Four-element array of numbers in the form [x1, y1, x2, y2]. If spatialref is present then these are map coordinates, otherwise they are pixel coordinates. Example:

"sub_rect" : [0, 0, 511, 511]

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


ENVISubsetRaster, ENVISubsetRaster::Dehydrate, ENVIHydratable, ENVIHydrate



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