ENVIGainOffsetWithThresholdRaster::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)

; Open an input file

File = Filepath('qb_boulder_msi', Subdir=['data'], $

Root_Dir=e.Root_Dir)

Raster = e.OpenRaster(File)

; Apply gains and offsets with thresholding

Gains = [2.00, 1.33, 1.20, 1.11]

Offsets = [12.33, 1.10, 6.00, 1.55]

Threshold_Min = [0, 0, 0, 0]

Threshold_Max = [65535, 65535, 65535, 65535]

GainOffsetImage = ENVIGainOffsetWithThresholdRaster(Raster, $

Gains, Offsets, $

THRESHOLD_MINIMUM=Threshold_Min, $

THRESHOLD_MAXIMUM=Threshold_Max)

; Retrieve the dehydrated hash

dehydratedForm = GainOffsetImage.Dehydrate()

GainOffsetImage.close

; Restore the object

newImage = ENVIGainOffsetWithThresholdRaster.Hydrate(dehydratedForm)

Print, newImage, /IMPLIED_PRINT

Syntax

Result = ENVIGainOffsetWithThresholdRaster.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 `GainOffsetWithThresholdRaster` indicating what object type the hash represents.
input_raster	Required. The input ENVIRaster for use in ENVI processing. Example: "input_raster": { "url": "/usr/local/INSTALL_DIR/envi/classic/data/bhtmref.img", "factory": "URLRaster" }
gain	Required. A double-precision array of data gain values (one per band) to apply to the input raster. Example: "gain": [2.0, 1.33, 1.2, 1.11, 2.6, 3.12],
name	A string that identifies the raster.
offset	Required. A double-precision array of data offset values (one per band) to apply to the input raster. Example: "offset" : [12.33, 1.10, 6.00, 1.55, 5.32, 4.05]
threshold_minimum	An array of minimum pixel values (one per band) for the output raster, after gains and offsets have been applied. The threshold_minimum key reduces the effects of dark pixels such as water or cloud shadows. Another example is constraining the output pixel values to the data range of the specified data type. You must set either the threshold_minimum or the threshold_maximum keys. Example: "threshold_minimum" : [0, 0, 0, 0, 0, 0]
threshold_maximum	An array of maximum pixel values (one per band) for the output raster, after gains and offsets have been applied. The threshold_maximum key reduces the effects of highly saturated pixels such as clouds or playas. Another example is constraining the output pixel values to the data range of the specified data type. You must set either the threshold_minimum or the threshold_maximum keys. Example: "threshold_maximum" : [65535, 65535, 65535, 65535, 655356, 65535]
data_type	A string indicating the output data type: `byte`: Byte (8 bits) `double`: Double-precision floating point (64 bits) `float`: Floating point (32 bits) `int`: Integer (16 bits) `long`: Long integer (32 bits) `uint`: Unsigned integer (16 bits) `ulong`: Unsigned long integer (32 bits) Example: "data_type" : "byte"

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