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Harris Geospatial / Docs Center / ENVI API / Crop Science / ENVIAgEnhanceCrops

ENVIAgEnhanceCrops

ENVIAgEnhanceCrops

This is a reference to an ENVIRaster where crops have been enhanced. The result can be passed to ENVIAgCropCount or ENVIAgCountAndRasterizeCrops. You can optionally set minimum and maximum pixel value thresholds on the input raster. ENVIAgEnhanceCrops then inverts the remaining pixel values, unless you choose to disable inversion.

This object is part of ENVI Crop Science, which requires a separate license and installation.

Example


This example performs the following steps:

  1. Opens an orthophoto of a citrus orchard.
  2. Creates a spectral subset consisting of the green band only.
  3. Masks out pixel values greater than 90 in the green band. These are primarily soil pixels that need to be masked out.
  4. Inverts the thresholded green band image to make the citrus trees appear bright.
  5. Displays the result.
; Start the application
e = ENVI()
 
; Open an input file
File = Filepath('CitrusOrthophoto.dat', $
  Subdir=['data','crop_science'], $
  Root_Dir=e.Root_Dir)
Raster = e.OpenRaster(File)
 
; Define a spectral subset consisting of
; the green band
greenBand = ENVISubsetRaster(Raster, BANDS=1)
 
; Enhance the crops
enhancedRaster = ENVIAgEnhanceCrops(greenBand, $
  INPUT_MAX=90, /INVERSE)
 
; Display the result
View = e.GetView()
Layer = View.CreateLayer(enhancedRaster)

Syntax


Result = ENVIAgEnhanceCrops(Input_Raster [, Keywords=value])

Return Value


This function returns a reference to an ENVIRaster object.

Arguments


Input_Raster

Specify a single-band ENVIRaste object. If you have a multispectral dataset, you must create a spectral subset consisting of only one band.

Methods


This function inherits the following methods from ENVIRaster. See the ENVIRaster topic in ENVI Help for details.

  • Close
  • CreatePyramid
  • CreateTileIterator
  • Dehydrate
  • Export
  • ExportROIs
  • GetData
  • Hydrate
  • Save
  • SetData
  • SetTile
  • WriteMetadata

Keywords


ERROR (optional)

Set this keyword to a named variable that will contain any error message issued during execution of this routine. If no error occurs, the ERROR variable will be set to a null string (''). If an error occurs and the routine is a function, then the function result will be undefined.

When this keyword is not set and an error occurs, ENVI returns to the caller and execution halts. In this case, the error message is contained within !ERROR_STATE and can be caught using IDL's CATCH routine. See IDL Help for more information on !ERROR_STATE and CATCH.

See the Manage Errors topic in ENVI Help for more information on error handling.

INPUT_MAX (optional)

Specify a maximum data value. Pixels greater than this value are set to NaN and will be ignored in subsequent processing. An example is setting a maximum value to remove shadows or bright soil pixels in an inverted green band image. These features have a similar brightness value to healthy vegetation and should be removed to reduce confusion in crop-counting tasks.

INPUT_MIN (optional)

Specify a minimum data value. Pixels less than this value are set to NaN and will be ignored in subsequent processing. An example is setting a mimimum value to remove dark shadows from a spectral index image (such as NDVI) or from a single-band image where the INVERSE keyword is not set.

INVERSE (optional)

Set this keyword to invert the data. An example is to invert the values in a green band.

OUTPUT_FILENAME (optional)

Set this keyword to a string with the fully qualified URI for the output raster file path. If you do not set this keyword, an output file will be automatically created.

Version History


1.0

Introduced

See Also


ENVIAgEnhanceCropsTask, ENVIAgCrops, ENVIAgCropCountTask, ENVIAgCountAndRasterizeCropsTask, ENVIAgCalculateAndRasterizeCropMetricsTask, ENVIAgCalculateAndRasterizeCropMetricsWithSpectralIndexTask, ENVIAgCalculateCropMetricsTask



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