RegridRasterSeries Task

This task reprojects a series of rasters to a common spatial grid, using a custom grid definition.

Example

This example builds a raster series from a collection of Landsat MSS, TM, and OLI-8 images. They are all georeferenced to the same coordinate system (UTM Zone 11, WGS-84), but their sizes and resolution are different. The example creates a custom grid defnition in a Nevada East State Plane (2701) coordinate system, then regrids the rasters in the series to this common grid. To determine the spatial extent of the grid, we used an online calculator to convert from known latitude/longitude coordinates to State Plane coordinates.

This example uses sample images files are available from our ENVI Tutorials web page. Click the Landsat Case Studies link to download the .zip file to your machine, then unzip the files. The files you will use in this example are located in the TimeSeries folder of the download. Update the file references in the example with the correct locations.

; Start the application

e = ENVI()

; Select input rasters

Files = FILE_SEARCH('C:\MyFolder\', 'LasVegas*.dat')

numRasters = N_Elements(Files)

rasters = ObjArr(numRasters)

FOR i=0, (numRasters-1) DO $

  rasters[i] = e.OpenRaster(Files[i])

; Get the build raster series task from the catalog of ENVITasks

Task = ENVITask('BuildRasterSeries')

; Define inputs

Task.INPUT_RASTERS = rasters

; Run the task

Task.Execute

Series = Task.OUTPUT_RASTERSERIES

; Define a custom spatial grid

CoordSys = ENVICoordSys(COORD_SYS_CODE=3421)

; Specify the spatial extent

; [xmin, ymax, xmax, ymin]

; x is easting and y is northing

; Units are U.S. Survey Feet

Extent = [710244.695D, 26847237.473D, 888005.795D, 26680703.416D]

Grid = ENVIGridDefinition(CoordSys, $

  EXTENT=Extent, PIXEL_SIZE=[98.4252, 98.4252])

; Get the regrid task from the catalog of ENVITasks

RegridTask = ENVITask('RegridRasterSeries')

; Define inputs

RegridTask.GRID_DEFINITION = Grid

RegridTask.INPUT_RASTERSERIES = Series

; Run the task

RegridTask.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, RegridTask.OUTPUT_RASTERSERIES

; Display the result

View = e.GetView()

Layer = View.CreateLayer(RegridTask.OUTPUT_RASTERSERIES)

View.Zoom, /FULL_EXTENT

Syntax

Result = ENVITask('RegridRasterSeries')

Input parameters (Set, Get): GRID_DEFINITION, INPUT_RASTERSERIES, OUTPUT_RASTERSERIES_URI, RESAMPLING

Output parameters (Get only): OUTPUT_RASTERSERIES

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

GRID_DEFINITION (required)

Set this parameter to an ENVIGridDefinition object that defines the custom grid.

INPUT_RASTERSERIES (required)

Specify a raster series to reproject.

OUTPUT_RASTERSERIES_URI (optional)

Specify a string with the fully-qualified path and filename for OUTPUT_RASTERSERIES.

RESAMPLING (optional)

Specify the resampling method to use when creating the spatial grid:

Nearest Neighbor (default): Uses the nearest pixel without any interpolation.
Bilinear: Performs a linear interpolation using four pixels to resample.
Cubic Convolution: Uses 16 pixels to approximate the sinc function using cubic polynomials to resample the image.