AgHotspotAnalysis Task
This task runs hotspot analysis on a single-band raster to look for areas that are statistically significant from surrounding areas. The resulting image shows the most significant features for the image.
The difference between this task and ENVIAgSpectralHotspotAnalysis is that you can pass in any single-band raster, not just a spectral index.
AgHotspotAnalysis Task is a metatask that runs the following tasks:
This task requires a separate license for the ENVI Crop Science Module; contact your sales representative for more information.
Example
This example creates a hotspot image that shows the relative health of alfalfa crops.
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 calculate a Modified Simple Ratio index. You do not necessarily have to use a spectral index image; you can pass in any single-band raster.
; 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')
; Get the task from the collection of tasks
Task = ENVITask('AgHotspotAnalysis')
; Define task inputs
Task.INPUT_RASTER = MSRImage
Task.DISTANCE = 10 ; meters
; 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(Raster)
Layer2 = View.CreateLayer(Task.OUTPUT_RASTER)
View.Zoom, 0.75
Syntax
Result = ENVITask('AgHotspotAnalysis')
Input properties (Set, Get): DISTANCE, INPUT_RASTER, OUTPUT_RASTER_URI
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:
This task also contains the following properties:
DISTANCE (required)
Specify the radius of the area around each pixel used to calculate the local mean. If the input raster has a valid spatial reference, then the radius is measured in meters. Otherwise, it is measured in pixels.
INPUT_RASTER (required)
Specify a single-band input raster.
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 of the associated OUTPUT_RASTER. If you do not specify this property, or set it to an exclamation symbol (!), a temporary file will be created.
Version History
Crop Science 1.0 |
Introduced |
See Also
AgSpectralHotspotAnalysis Task, AgHotspotColorSlice Task, AgCalculateGetisOrd Task