DimensionalityExpansionSpectralLibrary Task

This task performs dimensionality expansion on an input spectral library. This is useful if you perform dimensionality expansion on a raster and you want the spectral library to match the data space of that raster.

The task uses the number of bands and the wavelength values of an input raster to resample the spectral library into the same wavelength range as the input raster. Then it performs a dimensionality expansion on the resampled bands of the spectral library to match the data space of the dimensionality expansion raster.

See the Dimensionality Expansion topic for more information about the purpose of dimensionality expansion.

References

Chang, C.-I., J.-M. Liu, H. Ren, C.-M. Chung, C.-W. Yang, and D.-J. Ma. "Generalized Constrained Energy Minimization Approach to Subpixel Target Detection for Multispectral Imagery." Optical Engineering 39, No. 5 (2000): 1275-1281.

Heinz, D. "Constrained Least Squares Approaches to Target Detection and Image Classification for Remotely Sensed Images." Ph.D. dissertation. University of Maryland Baltimore County (2001).

Heinz, D., and C.-I. Chang. "Fully Constrained Least Squares Linear Spectral Mixture Analysis Method for Material Quantification in Hyperspectral Imagery." IEEE Transactions on Geoscience and Remote Sensing 39, No. 3 (2001): 529-545.

Heinz, D., and C.-I. Chang. "Unsupervised Fully Constrained Least Squares Linear Spectral Mixture Analysis Method for Multispectral Imagery." Proceedings of IGARSS 2000: 1681-1683.

Syntax

Result = ENVITask('DimensionalityExpansionSpectralLibrary')

Input properties (Set, Get): INPUT_RASTER, INPUT_SPECTRAL_LIBRARY, OUTPUT_SPECTRAL_LIBRARY_URI, REFLECTANCE_SCALE_FACTOR

Output properties (Get only): OUTPUT_SPECTRAL_LIBRARY

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:

COMMUTE_ON_DOWNSAMPLE

INPUT_RASTER (required)

Specify a multispectral input raster. The number of bands and the wavelengths of the input raster will determine how to resample the input spectral library prior to dimensionality expansion. The input raster must have wavelengths defined in its metadata if the number of bands is different between the spectral library and the input raster. Otherwise, wavelength metadata is not required.

INPUT_SPECTRAL_LIBRARY (required)

Specify the spectral library on which to perform dimensionality expansion.

OUTPUT_SPECTRAL_LIBRARY

This is a reference to the output ENVISpectralLibrary object.

OUTPUT_SPECTRAL_LIBRARY_URI (optional)

Specify a string with the fully qualified filename and path of the associated OUTPUT_SPECTRAL_LIBRARY. If you do not specify this property, or set it to an exclamation symbol (!), a temporary file will be created.

REFLECTANCE_SCALE_FACTOR (optional)

Specify a value by which to multiply the input spectral library values so they have a magnitude equivalent to the range of data in the dimensionality expansion raster.

For example, atmospheric correction tasks such as QUAC produce a reflectance image whose values range from 0 to 10000. If you use a spectral library whose reflectance values range from 0 to 1, you should set the reflectance scale factor to 10000 to match the dimensionality raster.

If the spectral library is already in the same data space as the dimensionality expansion raster, then you do not need to set a reflectance scale factor. This is the case if the spectral library was created from the n-Dimensionality Visualizer or by using mean spectra from regions of interest (ROIs).

Version History

ENVI 5.5. 2

Introduced

API Version

4.2