Geometric rectification program, front-end for RESAMPLE
GEOM is a restricted front-end to RESAMPLE. It permits scripts using the now-obsolete GEOM routine to run without modification. Note, however, that the WARPMETH argument is no longer supported. Applications needing a particular warp method to process images from oscillating-mirror sensors should use RESAMPLE explicitly, setting the IMGTYPE argument as appropriate.For additional information, see the help for RESAMPLE-GRID.
- IN
- Input image. The input image is a single or multi-band file with BYTE, INTEGER*2, INTEGER*4, or REAL*4 data type. Windowing is not allowed; band specifications are.
- OUT
- Output image. The output image is a single or multi-band file. The output image size is defined by the geometric mapping grid and the input window specification or the output window specification.
- INGRID
- Input grid file. The geometric mapping grid file contains output line and sample coordinates and their corresponding positions in the input image.
- INRWT(--)
- Input resampling weight table file. A file containing an externally generated table of resampling weights. This parameter is valid when RESAMP=TABLE. It is ignored for all other resampling methods.
- INTLIM(--)
- Interpolation limits. The minimum and maximum intensity allowed as a result of resampling. If a null value is received, INTLIM defaults to the maximum range for the image data type used.
- ODTYPE(SAME)
- Output data type. The data type of the output image.
= SAME: Same as input. = BYTE: BYTE (8-bit unsigned integer) (0 through 255) = I*2: INTEGER*2 (16-bit signed integer) (-32768 through 32767) = I*4: INTEGER*4 (32-bit signed integer) (-2147483648 through 2147483647) = R*4: REAL*4 (32-bit signed real) (System dependent)
- WINDOPT(OUT)
- Window option. The rectangular image window to be transformed may be specified either in terms of the input image or the output image.
= IN: Input window. = OUT: Output window.If window option OUT is specified, the window coordinates are used directly to select the desired region of the geometric mapping grid. The output window coordinates are relative to the coordinates used to define the mapping grid.If window option IN is specified, output image position is determined by the input window and the output image size is determined by the geometric mapping grid.
- WINDOW(--)
- Window specification. The values specifying the upper-left corner of the image window and its size are entered in the following order:
(SL) Starting line (SS) Starting sample (NL) Number of lines in window (NS) Number of samples per lineIf WINDOW is NULL, the entire image is processed according to values contained in the geometric mapping grid and the WINDOPT parameter is ignored.
- RESAMP(CC)
- Resampling method. Pixel values in the output image are determined by finding the corresponding location in the input image. The pixel location in the input image is a floating point value, i.e., it can fall between pixels. A method of interpolating a brightness value for that pixel location is therefore needed.
= NN: Nearest neighbor. Nearest neighbor interpolation uses the brightness value of the pixel closest to the calculated floating point pixel value. = BI: Bilinear. Bilinear interpolation uses a 2 x 2 block of input pixels which surround the calculated floating point pixel value to determine the output pixel brightness value. = CC: Cubic convolution. Cubic convolution interpolation uses a 4 x 4 block of input pixels which surround the calculated floating point pixel value to determine the output pixel brightness value. = TABLE: Table-based. Table-based resampling uses a N x M block of input pixels which surround the calculated floating point pixel value to determine the output pixel brightness value. The dimensions N and M, as well as the resampling kernel (resampling weights), are contained in the user-entered file of resampling weights.
- PCCALPHA(-0.5)
- Parametric cubic convolution alpha parameter. Commonly used values are -1.0 and -0.5; values -3.0 through 3.0 produce reasonable results. Other values may cause unpredictable results but are permitted for experimental purposes. This parameter is valid when RESAMP=CC. It is ignored for all other resampling methods.
- BACKGRND(0.0)
- Background value. Gray level fill value assigned to all output pixels which map to locations outside the edges of the input image. If the resampling method is bilinear, cubic convolution, or table-based, an output pixel is considered to fall outside the input image if any of the input pixels needed for the interpolation are at positions outside the input edges.
- GRIDFLG(YES)
- Grid flag. Flag to determine whether grid correctness should be checked. This option may be useful with certain global projections where grid wrapping occurs. In certain instances, if grid checking is not done, invalid output data may occur.
= YES: Check for grid correctness = NO: Do not check for grid correctness
The geometric mapping grid file MAP.GRD is used to map IMAGE.DAT to IMAGE.OUT. Cubic convolution with an alpha parameter of -0.5 is the resampling method used. Since a window was not specified, the output image size is determined by the geometric mapping grid.
IMAGE.DAT will be mapped to IMAGE.OUT. An output window of (1,1,512,512) limits the output image to 512 lines by 512 samples. Bilinear interpolation resampling is used and all background areas are set to 255.0.
IMAGE.DAT is mapped to IMAGE.OUT using MAP.GRD. The first 256 lines and 256 samples of the input image will be mapped. The output image size is determined by the mapping grid. Nearest neighbor interpolation is used.
IMAGE.DAT is mapped to IMAGE.OUT using the mapping grid MAP.GRD and table-based resampling. The user-entered table of resampling weights is contained in TAB.TAB. The output image size will be 512 lines by 512 samples. This is the method of operation used (RESAMP=TABLE) when applying a restoration kernel to an image. No grid-wrapping check is performed on the image.
for RESAMPLE-GRID.