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

This example uses data files that are available on the ENVI Resource DVD (in the image_reg folder) or from the ENVI Tutorials web page. Click the "ENVI Tutorial Data" hyperlink. Copy the images to your local drive.

; Start the application

e = ENVI(/HEADLESS)

; Open two input images

File1 = 'quickbird_2.4m.dat'

Raster1 = e.OpenRaster(File1)

File2 = 'ikonos_4.0m.dat'

Raster2 = e.OpenRaster(File2)

; Open an existing tie point file

tiePointFile = 'SampleTiePoints.pts'

tiePoints = ENVITiePointSet(tiePointFile, $

  INPUT_RASTER1=Raster1, INPUT_RASTER2=Raster2)

; Retrieve the dehydrated hash

dehydratedForm = tiePoints.Dehydrate()

tiePoints.close

; Restore the object

newTiePoints = ENVITiePointSet.Hydrate(dehydratedForm)

Print, newTiePoints, /IMPLIED_PRINT

Syntax

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

Return Value

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

Arguments

DehydratedForm

The form of the hash depends on if you have created or updated the tiepoint set from raw data or if the tiepoint set has been loaded from a file.

Tiepoints loaded from a file:

"url" : "/usr/local/harris/envi/mydata/tiepoints.pts"

    "input_raster1": {        
     "url": "/usr/local/harris/envi/mydata/tiepoints/myfile.dat",       
     "factory": "URLRaster"    
}

Tiepoints created or updated from an array:

"tiepoints": [295.48999023437500, 221.58000183105469, 543.38000488281250, 293.51998901367187],

    "input_raster1": {        
     "url": "/usr/local/harris/envi/mydata/tiepoints/myfile.dat",       
     "factory": "URLRaster"    
}

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.

API Version

3.2

Version History

See Also

ENVITiePointSet, ENVITiePointSet::Dehydrate, ENVIHydratable, ENVIHydrate