GeographicSubsetRaster Task

This task subsets a raster spatially (by geographic location) and/or spectrally.

Example

; Start the application

e = ENVI()

; Open an input file

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

Root_Dir=e.Root_Dir)

Raster = e.OpenRaster(File)

; Define the spatial range of the subRect

subRect = [Raster.nSamples/4, Raster.nLines/4, $

Raster.nSamples*3/4, Raster.nLines*3/4]

; Get the spatial reference of the raster

SpatialRef = Raster.SPATIALREF

; Convert file coordinates to map coordinates

SpatialRef.ConvertFileToMap, subRect[0], subRect[1], ULx, ULy

SpatialRef.ConvertFileToMap, subRect[0], subRect[3], LLx, LLy

SpatialRef.ConvertFileToMap, subRect[2], subRect[1], URx, URy

SpatialRef.ConvertFileToMap, subRect[2], subRect[3], LRx, LRy

geoRect = [ LLx, LLy, URx, URy ]

; Get the task from the catalog of ENVITasks

Task = ENVITask('GeographicSubsetRaster')

; Define inputs

Task.INPUT_RASTER = Raster

Task.SUB_RECT = geoRect

; 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()

Layer1 = View.CreateLayer(Task.OUTPUT_RASTER)

Syntax

Result = ENVITask('GeographicSubsetRaster')

Input parameters (Set, Get): BANDS, INPUT_RASTER, OUTPUT_RASTER_URI, SPATIAL_REFERENCE, SUB_RECT

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

BANDS (optional)

Specify an array of band indices to include in the OUTPUT_RASTER. The indices are zero-based, and a scalar is allowed for single-band output.

INPUT_RASTER (required)

Specify the input ENVIRaster to subset.

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.

SPATIAL_REFERENCE (optional)

Specify an ENVIPseudoRasterSpatialRef, ENVIRPCRasterSpatialRef, or ENVIStandardRasterSpatialRef object that indicates the spatial reference of the spatial subset. If you do not specify this parameter, ENVI will use the spatial reference of the input raster by default.

SUB_RECT (required)

Set this parameter to a four-element array expressing the spatial range of the raster data. The array is of the form [minX, minY, maxX, maxY]

Values can be map coordinates (x=eastings, y=northings) or geographic coordinates (x=longitude, y=latitude), depending on the spatial reference object used.