ENVIMetaspectralRaster::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.

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

For additional information, see What are Hydrate and Dehydrate routines used for?

Example

; Start the application

e = ENVI(/HEADLESS)

; Select a Landsat-8 metadata file

File = 'LC80410302013229LGN00_MTL.txt'

Raster = e.OpenRaster(File)

; Landsat-8 data are stored in a 5-element

; array. Multispectral bands are stored in the

; first array element. Thermal bands are stored

; in the fourth array element.

OLIBands = Raster[0]

TIRBands = Raster[3]

; Create a metaspectral raster

MSRaster = ENVIMetaspectralRaster([OLIBands,TIRBands])

; Retrieve the dehydrated hash

dehydratedForm = MSRaster.Dehydrate()

MSRaster.close

; Restore the object

newImage = ENVIMetaspectralRaster.Hydrate(dehydratedForm)

Print, newImage, /IMPLIED_PRINT

Syntax

Result = ENVIMetaspectralRaster.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 `MetaspectralRaster` indicating what object type the hash represents.
input_rasters	Required. A list of input ENVIRasters for use in ENVI processing. The following example uses a fictitious filename for illustration: "input_rasters": [ { "factory" : "URLRaster", "dataset_name" : "multispectral", "dataset_index" : 0, "url" : "/usr/local/data/landsat8_MTL.txt" }, { "factory" : "URLRaster", "dataset_name" : "cirrus", "dataset_index" : 2, "url" : "/usr/local/data/landsat8_MTL.txt" }, { "factory" : "URLRaster", "dataset_name" : "thermal", "dataset_index" : 3, "url" : "/usr/local/data/landsat8_MTL.txt" }]
name	A string that identifies the raster.
spatialref	The hash representation of a spatial reference of type ENVIStandardRasterSpatialRef, ENVIPseudoRasterSpatialRef or ENVIRPCRasterSpatialRef. 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] }

Keywords

ERROR (optional)

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

4.2