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ENVIImageBandDifferenceTask

ENVIImageBandDifferenceTask

This task performs a difference analysis on a specific band in two images.

Example


This example performs a difference analysis between two images from different dates. The images represent NCEP-Reanalysis 2 air temperatures (K) at the 1000-isobar level, at 0600 hours Zulu time. The first image is from 29 December 2012, and the second is from 31 December 2012. Each image has one band. This example uses sample data from the ENVI installation path.

; Start the application
e = ENVI()
 
TimeSeriesDir = Filepath('', Subdir=['data','time_series'], $
  Root_Dir = e.Root_Dir)
files = File_Search(TimeSeriesDir, 'AirTemp*.dat')
numRasters = N_Elements(files)
rasters = ObjArr(numRasters)
FOR i=0, (numRasters-1) DO $
  rasters[i] = e.OpenRaster(files[i])
   
; Get the task from the catalog of ENVITasks
Task = ENVITask('BuildTimeSeries')
 
; Define inputs
Task.INPUT_RASTERS = rasters
 
; Run the task
Task.Execute
 
; Get the raster that corresponds to 0600, 29 December 2012 (index #1)
; Indices are zero-based.
SeriesFile = Task.OUTPUT_RASTERSERIES
SeriesFile.Set, 0
Image1 = SeriesFile.Raster
 
; Get the raster that corresponds to 0600, 31 December 2012 (index #9)
; Indices are zero-based.
SeriesFile.Set, 8
Image2 = SeriesFile.Raster
 
; Get the task from the catalog of ENVITasks
Task = ENVITask('ImageBandDifference')
 
; Define inputs
Task.INPUT_RASTER1 = Image1
Task.INPUT_RASTER2 = Image2
 
; Run the task
Task.Execute
 
; Get the collection of data objects currently available in the Data Manager
DataColl = e.Data
 
; Add the output to the Data Manager
DataColl.Add, Task.OUTPUT_RASTER
 
; Display the result
View = e.GetView()
Layer = View.CreateLayer(Task.OUTPUT_RASTER)

Syntax


Result = ENVITask('ImageBandDifference')

Input properties (Set, Get): INPUT_RASTER1, INPUT_RASTER2, OUTPUT_RASTER_URI

Output properties (Get only): OUTPUT_RASTER

Properties marked as "Set" are those that you can set to specific values. You can also retrieve their current values any time. Properties marked as "Get" are those whose values you can retrieve but not set.

Methods


This task inherits the following methods from ENVITask:

AddParameter

Execute

Parameter

ParameterNames

RemoveParameter

Properties


This task inherits the following properties from ENVITask:

COMMUTE_ON_DOWNSAMPLE

COMMUTE_ON_SUBSET

DESCRIPTION

DISPLAY_NAME

NAME

REVISION

TAGS

This task also contains the following properties:

INPUT_RASTER1 (required)

Specify a single-band raster on which to perform an image difference of input band.

INPUT_RASTER2 (required)

Specify a second single-band raster on which to perform an image difference of input band.

OUTPUT_RASTER

This is a reference to the output raster of filetype ENVI. It inherits the same map information (projection, datum, pixel size, image rotation) and wavelengths as INPUT_RASTER1.

OUTPUT_RASTER_URI (optional)

Specify a string with the fully qualified filename and path of the associated OUTPUT_RASTER. If you do not specify this property, or set it to an exclamation symbol (!), a temporary file will be created.

Version History


ENVI 5.2

Introduced

API Version


3.3

See Also


ENVITask, ENVITask::Parameter, ENVISubsetRaster, ENVISAMImageDifferenceTask



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