This task subsets a raster spectrally using the BandMax algorithm.
The virtual raster associated with this task is ENVIBandMaxSubsetRaster.
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
Task = ENVITask('BandMaxSubsetRaster')
Task.INPUT_RASTER = raster
Task.TARGET = targetSpec
Task.BACKGROUND = backgroundSpec
Task.THRESHOLD = thresh
Task.Execute
DataColl = e.Data
DataColl.Add, Task.OUTPUT_RASTER
View = e.GetView()
Layer = View.CreateLayer(Task.OUTPUT_RASTER)
Syntax
Result = ENVITask('BandMaxSubsetRaster')
Input parameters (Set, Get): BACKGROUND, INPUT_RASTER, NUMBER_BANDS, OUTPUT_RASTER_URI, TARGET, THRESHOLD
Output parameters (Get only): OUTPUT_RASTER
Parameters marked as "Set" are those that you can set to specific values. You can also retrieve their current values any time. Parameters marked as "Get" are those whose values you can retrieve but not set.
Input Parameters
BACKGROUND (required)
Specify the background spectra as a floating-point array of [number of bands, number of background spectra].
INPUT_RASTER (required)
Specify the input ENVIRaster to subset.
NUMBER_BANDS (optional)
Specify the number of significant bands for BandMax subset raster. If this value and THRESHOLD are undefined, this task spectrally subsets raster using the BandMax calculated threshold.
OUTPUT_RASTER_URI (optional)
Specify a string with the fully qualified filename and path to export the associated OUTPUT_RASTER.
- If you set this parameter to an asterisk symbol (*), the output raster will be virtual and not written to disk.
- If you do not specify this parameter, or set it to an exclamation symbol (!), a temporary file will be created.
- If you set it to the hash symbol (#), ENVI creates a file in the temporary directory, but this file will not be deleted when ENVI closes.
TARGET (required)
Specify the target spectra as a floating-point array of [number of bands, number of target spectra].
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.
Output Parameters
OUTPUT_RASTER
This is a reference to the output raster of filetype ENVI.
Methods
Execute
Parameter
ParameterNames
Properties
DESCRIPTION
DISPLAY_NAME
NAME
REVISION
TAGS
Version History
See Also
ENVITask, SubsetRaster Task