ENVIRootStretchRaster::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', ROOT_DIR=e.ROOT_DIR, $

SUBDIRECTORY = ['data'])

raster = e.OpenRaster(file)

; Create the stretch raster

stretchRaster = ENVIRootStretchRaster(raster, $

MIN=[138,154,92,52], MAX=[1492,2047,1785,1807], ROOT_INDEX=2.0)

; Retrieve the dehydrated hash

dehydratedForm = stretchRaster.Dehydrate()

stretchRaster.close

; Restore the object

newImage = ENVIRootStretchRaster.Hydrate(dehydratedForm)

Print, newImage, /IMPLIED_PRINT

Syntax

Result = ENVIRootStretchRaster.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 `RootStretchRaster` 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/data/qb_boulder_msi", "factory": "URLRaster" }
min	Required. Minimum value to be considered, also known as the "black point." If this value is a scalar, it applies to all bands. If it is an array, it must have the same number of elements as the input raster has bands. Example: "min": [138, 154, 92, 52],
max	Required. Maximum value to be considered, also known as the "white point." If the value is a scalar, it applies to all bands. If it is an array, it must have the same number of elements as the input raster has bands. Example: "max": [1492, 2047, 1785, 1807],
brightness	Integer value from 0 to 100, indicating the brightness level to display. The default value is 50 if no brightness is specified. You can also set this value to a scalar or an array with the same number of elements as the raster has bands. Example: "brightness": [65, 75, 85, 95],
name	A string that identifies the raster.
root_index	The root index function applied to the stretch. For example, a value of 2.0 indicates a square root, and a 3.0 value indicates a cube root. If not specified, then 2.0 is the default. Example: "root_index" : 3

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