HotspotColorSlice Task

AgHotspotColorSlice Task

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

This task requires a separate license for the ENVI Crop Science Module; contact your sales representative for more information.

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 parameters (Set, Get): INPUT_RASTER, OUTPUT_RASTER_URI

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

INPUT_RASTER (required)

Specify a single-band raster.

OUTPUT_RASTER_URI (optional)

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

If you do not specify this parameter, or set it to an exclamation symbol (!), ENVI creates a temporary file.
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.