ISIS 3 Application Documentation
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Resample an image to correct for spectral smile
This program will spectrally resample an image. A common use is to correct for spectral smile. The pixels of each spectrum must be spatially aligned (i.e., The pixel at (sample, line, band) (1,1,1) represents the same point on the target body as (1,1,2), and (1,1,3), .... and so on for all spectra in the image.) For instruments where the spectra are not spatially aligned, the ISIS program cam2map can be used to project the cube.
The program requires two spectral definition files as input. See the parameters SMILEDEF and OBJECTIVE for specifics. SMILEDEF is used to define the wavelength and filter width of each element in the sensor. OBJECTIVE is used to define the wavelength and filter width of the pixels in the output cube.
Spectral definitions can have multiple sections. Each section represents the wavelength and filter width of a subset of bands. For example: a 256 band image may have two sections, where the first 200 entries define the wavelength centers and filter widths for 2.489 to 1.2204 um, and the last 56 entries define the wavelength centers and filter widths for 2.2623 to 2.0898 um. Each section is defined by a reversal of the wavelength center values (i.e., 2.2, 2.3, 2.20, 2.25, 2.30 would define two sections with two entries in the first and three in the second). The input and output spectral definitions must have the same number of sections, and should contain wavelengths in the same range. Spectral resampling will not cross section boundaries.
WARNING: This program is computationally intense and may take a long time to process large cubes.
Use this parameter to select the file name of a multi-band cube with spectral smile that needs to be corrected. The cube must have an associated ISIS camera model and may be projected as long as the camera can still be used (i.e., The instrument and kernels groups in the label are intact). See the main description for information about how this cube must be spatially aligned.
The output cube file that will contain the smile-corrected cube. This cube will be created using the same number of samples and lines as the input cube (FROM) and the number of bands in the OBJECTIVE spectral definition.
Spectral definition file containing center wavelength and filter width information for each element of the sensor. Typically elements are the pixels of the sensor, requiring a two-dimensional set of wavelength center and filter width pairs. Elements can also be defined as the lines of the sensor, requiring a one-dimensional set of wavelength center and filter width pairs. The former case is typically used to correct spectral smile and the latter case to to spectrally resample an image that does not contain spectral smile.
The two-dimensional definition is supported as a ISIS cube. The spectral definition cube must have the same number of samples as the sensor, a number of bands equal to the number of lines on the sensor, and two lines. The first line contains the center wavelengths and the second contains the filter widths.
The one-dimensional definition is supported as a text file with comma separated values. Each line contains the information for one band. Each line has center wavelength and filter width separated by a comma.
The spectral definition desired for the output cube. Each spectrum of the input cube will be resampled to fit this definition. Both one-dimensional and two-dimensional definitions are allowed. The one-dimensional type is used to flatten out a spectral smile. See the description for the SMILEDEF parameter for more information regarding spectral definition files.