This task creates a 2D array of subrects based on a specified number of pixels. A subrect is a bounding box used to spatially subset a raster. It is part of a sequence for dicing rasters:
Consider using ENVIDiceRasterByPixel to perform these steps in one task.
Example
e = ENVI()
File = Filepath('qb_boulder_msi', Subdir=['data'], $
Root_Dir=e.Root_Dir)
Raster = e.OpenRaster(File)
Task = ENVITask('CreateSubrectsFromPixels')
Task.NUMBER_OF_X_PIXELS = 250
Task.NUMBER_OF_Y_PIXELS = 350
Task.NCOLUMNS = 1000
Task.NROWS = 1000
Task.Execute
Subrects = Task.SUBRECTS
SubNames = Task.SUBRECT_NAMES
Help, Subrects
IDL prints:
SUBRECTS LONG =Array[4, 12]
This shows that 12 subrects were created with four coordinate points each. Now pass the subrects to the DiceRasterBySubrects task:
DiceTask = ENVITask('DiceRasterBySubrects')
DiceTask.INPUT_RASTER = Raster
DiceTask.SUBRECT_ARRAY = Subrects
DiceTask.SUBRECT_NAMES = SubNames
DiceTask.Execute
ExportTask = ENVITask('ExportRastersToDirectory')
ExportTask.INPUT_RASTER = DiceTask.OUTPUT_RASTER
ExportTask.OUTPUT_DIRECTORY = Filepath('', /TMP)
ExportTask.Execute
Syntax
Result = ENVITask('CreateSubrectsFromPixels')
Input parameters (Set, Get): NCOLUMNS, NROWS, NUMBER_OF_X_PIXELS, NUMBER_OF_Y_PIXELS
Output parameters (Get only): SUBRECTS, SUBRECT_NAMES
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
NCOLUMNS (required)
Specify the number of columns in the raster.
NROWS (required)
Specify the number of rows in the raster.
NUMBER_OF_X_PIXELS (required)
Specify the number of resulting pixels per tile in the X direction.
NUMBER_OF_Y_PIXELS (required)
Specify the number of resulting pixels per tile in the Y direction.
Output Parameters
SUBRECTS
This parameter contains an array of output subrects.
SUBRECT_NAMES
This parameter contains the names of each output subrect.
Methods
Execute
Parameter
ParameterNames
Properties
DESCRIPTION
DISPLAY_NAME
NAME
REVISION
TAGS
Version History
See Also
ENVITask, ENVITask::Parameter, ENVISubsetRaster, CreateSubrectsFromDistance Task, CreateSubrectsFromROI Task, CreateSubrectsFromTileCount Task, CreateSubrectsFromVector Task, DiceRasterByDistance Task, DiceRasterByPixel Task, DiceRasterBySubrects Task, DiceRasterByTileCount Task, DiceRasterByVector Task, ExportRastersToDirectory Task