ENVIAgHotspotColorSliceTask

This task creates a classification raster based on color slices that represent relative Z-scores calculated from Getis-Ord Gi* hotspot analysis.

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

Example

This example first creates a Z-score raster from a spectral index image of alfalfa fields. It then creates a classification raster with color slices that represent the relative Z-scores.

The source image consists of layer-stacked Sentinel-2A visible, near-infrared, and shortwave-infrared bands with a spatial resolution of 10 meters. The image is from eastern Idaho, USA. The accompanying region of interest (ROI) file encompasses alfalfa fields. It is used to mask out all non-alfalfa pixels from the source image. The masked raster is then used to create a Modified Simple Ratio index, which is used as input to the Getis-Ord statistics calculation.

; Start the application

e = ENVI()

; Open an input file

File = Filepath('CircularFields_Sentinel2A.dat', $

  Subdir=['data', 'crop_science'], $

  Root_Dir=e.Root_Dir)

Raster = e.OpenRaster(File)

; Only process the actively growing fields

; using an ROI mask

ROIFile = Filepath('CircularFields_AlfalfaROI.xml', $

  Subdir=['data', 'crop_science'], $

  Root_Dir=e.Root_Dir)

ROI = e.OpenROI(ROIFile)

maskedRaster = ENVIROIMaskRaster(Raster, ROI)

; Create a Modified Simple Ratio index

MSRImage = ENVISpectralIndexRaster(maskedRaster, 'MSR')

; Create a Z-score raster

GetisOrdTask = ENVITask('AgCalculateGetisOrd')

GetisOrdTask.INPUT_RASTER = MSRImage

GetisOrdTask.DISTANCE = 10 ; meters

GetisOrdTask.Execute

; Get the color slice task from the catalog of ENVITasks

Task = ENVITask('AgHotspotColorSlice')

; Define the task inputs

Task.INPUT_RASTER = GetisOrdTask.OUTPUT_RASTER

; 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('AgHotspotColorSlice')

Input properties (Set, Get): INPUT_RASTER, OUTPUT_RASTER_URI

Output properties (Get only): OUTPUT_RASTER

Properties marked as "Init" are applied only during the initial creation of the object. Properties marked as "Set" are those that you can set to specific values after the object has been created. 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. See the ENVITask topic in ENVI Help.

AddParameter
Execute
Parameter
ParameterNames
RemoveParameters

Properties

This task inherits the following properties from ENVITask:

COMMUTE_ON_DOWNSAMPLE

COMMUTE_ON_SUBSET

DESCRIPTION

DISPLAY_NAME

NAME

REVISION

See the ENVITask topic in ENVI Help for details.

This task also contains the following properties:

INPUT_RASTER (required)

Specify a single-band raster.

OUTPUT_RASTER

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

OUTPUT_RASTER_URI (optional)

Specify a string with the fully qualified filename and path of the output raster. If you do not specify this property, the output raster is only temporary. Once the raster has no remaining references, ENVI deletes the temporary file.

Version History

1.0	Introduced