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 properties (Set, Get): BANDS, INPUT_RASTER, OUTPUT_RASTER_URI, SPATIAL_REFERENCE, SUB_RECT

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:

Properties

This task inherits the following properties from ENVITask:

COMMUTE_ON_DOWNSAMPLE

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

This is a reference to the output raster of filetype ENVI.

OUTPUT_RASTER_URI (optional)

Specify a string with the fully qualified filename and path to export the associated OUTPUT_RASTER.

If you set this property to an asterisk symbol (*), the output raster will be virtual and not written to disk.
If you do not specify this property, or set it to an exclamation symbol (!), a temporary file will be created.

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 property, ENVI will use the spatial reference of the input raster by default.

SUB_RECT (required)

Set this property 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.

Version History

ENVI 5.2. 1	Introduced
ENVI 5.5	OUTPUT_RASTER_URI now supports '*', which allows OUTPUT_RASTER to be virtual output.

API Version

4.2