Use this procedure to convert a set of irregularly gridded x,y,z points to a raster image.

Syntax

ENVI_DOIT, 'ENVI_GRID_DOIT' [, /EXTRAP] [, I_PROJ=structure], /IN_MEMORY, INTERP={0 | 1}, O_PROJ=structure, OUT_DT={1 | 2 | 3 | 4 | 5 | 6}, OUT_NAME=string, PIXEL_SIZE=array, R_FID=variable [, XMAX=value] [, XMIN=value], X_PTS=array [, YMAX=value] [, YMIN=value], Y_PTS=array, Z_PTS=array

Keywords

EXTRAP (optional)

Set this keyword to allow extrapolation to the outer edge of the image. Otherwise, the image is defined by the bounding polygon around the exterior points, and all other points are set to 0.

I_PROJ (optional)

Use this keyword to specify the input map projection structure for the irregularly gridded arrays of points, X_PTS and Y_PTS. Use ENVI_PROJ_CREATE to define a projection.

IN_MEMORY

Set this keyword to specify that output should be stored in memory. If you do not set IN_MEMORY, output will be stored on disk and you must specify OUT_NAME (see below).

INTERP

Set this keyword to one of the following values to specify the type of interpolation.

  • 0: Linear
  • 1: Quintic

O_PROJ

Use this keyword to specify the output map projection structure for the gridded points. The points are automatically converted from the input projection to the output projection. Use ENVI_PROJ_CREATE to define a projection.

OUT_DT

This keyword indicates the IDL data type of the output data. Set the keyword to one of the following integer values:

  • 1: Byte (8 bits)
  • 2: Integer (16 bits)
  • 3: Long integer (32 bits)
  • 4: Floating-point (32 bits)
  • 5: Double-precision floating-point (64 bits)
  • 6: Complex (2x32 bits)

OUT_NAME

Use this keyword to specify a string with the output filename for the resulting data. If you set the keyword IN_MEMORY, you do not need to specify OUT_NAME.

PIXEL_SIZE

Use this keyword to specify the pixel size of the output image. PIXEL_SIZE is a two-element array of floating-point values representing the x and y pixel sizes, respectively.

R_FID

ENVI Classic library routines that result in new images also have an R_FID, or “returned FID.” This is simply a named variable containing the file ID to access the processed data. Specifying this keyword saves you the step of opening the new file from disk.

XMAX (optional)

Use this keyword to specify the maximum x value to use. The default is to use the maximum of the X_PTS array.

XMIN (optional)

Use this keyword to specify the minimum x value to use. The default is to use the minimum of the X_PTS array.

X_PTS

Use this keyword to specify a corresponding array of irregularly gridded x points. The number of elements of X_PTS, Y_PTS, and Z_PTS must be equal.

YMAX (optional)

Use this keyword to specify the maximum y value to use. The default is to use the maximum of the Y_PTS array.

YMIN (optional)

Use this keyword to specify the minimum y value to use. The default is to use the minimum of the Y_PTS array.

Y_PTS

Use this keyword to specify a corresponding array of irregularly gridded y points. The number of elements of X_PTS, Y_PTS, and Z_PTS must be equal.

Z_PTS

Use this keyword to specify a corresponding array of irregularly gridded z points. The number of elements of X_PTS, Y_PTS, and Z_PTS must be equal.

API Version

4.2