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
e = ENVI()
File = Filepath('AVIRISReflectanceSubset.dat', $
SUBDIR=['data', 'hyperspectral'], $
ROOT_DIR=e.Root_Dir)
Raster = e.OpenRaster(File)
nSpectra = 9d
roi1 = EnviRoi(NAME='Green Field')
pixelAddr1 = [[77,182],[78,182],[79,182], $
[77,183],[78,183],[79,183], $
[77,184],[78,184],[79,184]]
roi1.AddPixels, pixelAddr1, SPATIALREF=raster.SpatialRef
roi2 = EnviRoi(NAME='Soil')
pixelAddr2 = [[386,285],[387,285],[388,285], $
[386,286],[387,286],[388,286], $
[386,287],[387,287],[388,287]]
roi2.AddPixels, pixelAddr2, SPATIALREF=raster.SpatialRef
roi3 = EnviRoi(NAME='Ground')
pixelAddr3 = [[296,326],[297,326],[298,326], $
[296,327],[297,327],[298,327], $
[296,328],[297,328],[298,328]]
roi3.AddPixels, pixelAddr3, SPATIALREF=raster.SpatialRef
spectra1 = raster.GetData(ROI=roi1)
mean1 = Total(spectra1,1) / nSpectra
spectra2 = raster.Getdata(ROI=roi2)
mean2 = Total(spectra2,1) / nSpectra
spectra3 = raster.GetData(ROI=roi3)
mean3 = Total(spectra3,1) / nSpectra
targetSpec = [[mean1], [mean2]]
backgroundSpec = mean3
thresh = 0.387
Subset = ENVIBandMaxSubsetRaster(raster, targetSpec, $
backgroundSpec, THRESHOLD=thresh)
dehydratedForm = Subset.Dehydrate()
Subset.close
newImage = ENVIBandMaxSubsetRaster.Hydrate(dehydratedForm)
Print, newImage, /IMPLIED_PRINT
Syntax
Result = ENVIBandMaxSubsetRaster.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.
|
background |
Required. An array that specifies the background spectra. Example:
[[0.0859, 0.0808, 0.0826, 0.0804, 0.0762, 0.0739, 0.0739], [0.1343, 0.1357, 0.1354, 0.1335, 0.1297, 0.1276, 0.1245]]
|
input_raster |
Required. The input ENVIRaster for use in ENVI processing. Example:
"input_raster": { "url": "/usr/local/INSTALL_DIR/envi/data/hyperspectral/AVIRISReflectanceSubset.dat", "factory": "URLRaster" }
|
name |
A string that identifies the raster.
|
number_bands |
Optional. The number of significant bands for the BandMax subset raster. If this value and threshold are undefined, BandMax spectrally subsets the raster using the calculated threshold. Example:
56
|
target |
Required. An array that specifies the target spectra. Example:
[[0.3918, 0.3954, 0.3983, 0.4005, 0.4024, 0.4054, 0.4044], [0.2138, 0.2707, 0.2599, 0.2271, 0.2172, 0.2107, 0.2129], [0.1479, 0.1509, 0.1494, 0.1488, 0.1468, 0.1429, 0.1448]]
|
threshold |
Optional. Specify a floating-point value ranging from 0.0 to 1.0. This value represents the threshold for the minimum significance value that determines which bands are in the output raster of this task. The default threshold value is calculated to select 25% of the input bands, but never less than six bands. If this value and number_bands are undefined, the default threshold value is used for output raster. Example:
0.387
|
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
API Version
4.3
See Also
ENVIBandMaxSubsetRaster, ENVIBandMaxSubsetRaster::Dehydrate, ENVIHydratable, ENVIHydrate