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sigmerg(file, dsig, valu, thrs, bias, dbsn, dbsd)
| Name | Type | Caption | Length | Value range |
|---|---|---|---|---|
| FILE * | str | Input file name | 1 - | |
| DSIG * | List[int] | Input class signature segments | 2 - 2 | |
| VALU | List[int] | Gray-level values | 0 - 1 | 1 - 254 |
| THRS | List[float] | Gaussian threshold | 0 - 1 | |
| BIAS | List[float] | Class bias | 0 - 1 | |
| DBSN | str | Output segment name | 0 - 8 | |
| DBSD | str | Output segment description | 0 - 64 |
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FILE
Specifies the name of the PCIDSK image file that contains the signatures to merge, and to receive the output merged signature.
DSIG
Specifies the two class segment segments (type 121) to merge.
Specified segments must have the same number and set of channels.
VALU
Specifies an integer value (1-254) that represents the class in the output classification theme map created by MLC.
Values of 0 and 255 are invalid, as they will be assigned to the null and multiply-classified pixels of the output theme map, respectively.
If this parameter is not specified, the value is inherited from the value held in the first input signature segment (DSIG1).
THRS
Specifies the Gaussian feature-space threshold. The greater this value is, the larger the hyperellipsoid or parallelepiped in feature space.
This value is a REAL number in units of standard deviation.
If this parameter is not specified, the value is inherited from the value held in the first input signature segment (DSIG1).
BIAS
Specifies the BIAS, or relative 'a priori' probabilities for the class. If all classes have equal bias, their 'a priori' probabilities are equal.
This parameter "biases" the maximum likelihood classifier's assignment of a class to a point that lies in overlapping classes in feature-space. This value is a REAL number.
If this parameter is not specified, the value is inherited from the value held in the first input signature segment (DSIG1).
DBSN
Specifies a name (up to 8 characters) for the output segment.
If this parameter is not specified, the value is inherited from the value held in the first input signature segment (DSIG1).
DBSD
Describes (in up to 64 characters) the contents or origins of the output data.
If this parameter is not specified, the value is inherited from the value held in the first input signature segment (DSIG1).
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Returns: New segment number
Type: PCI_INT
Parameter: LASC
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SIGMERG merges two existing signature class segments (DSIG) to create a new signature segment.
The merged signature's value (VALU), threshold (THRS), bias (BIAS), segment name (DBSN), and segment description (DBSD) may be specified by the user. Any values not specified will be inherited from the corresponding values of the first input signature segment.
Use SIGMERG for the aggregation of class signature segments, rather than for merging training area bitmaps and creating signature segments. Certain limitations, however, should be recognized. First, the two signature segments used for merging must have been created using the same number and set of input channels. Second, if the two signatures used as input were created from overlapping training area bitmaps, the results will be erroneous, because the overlap area will be sampled twice.
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Merge signature segments 21 and 22, in the file 'irvine.pix'.
from pci.sigmerg import sigmerg
file = "irvine.pix" # input file
dsig = [21,22] # input signature segments
valu = [] # inherit value from signature 21
thrs = [] # inherit value from signature 21
bias = [] # inherit value from signature 21
dbsn = "" # inherit value from signature 21
dbsd = "" # no segment description
lasc = sigmerg( file, dsig, valu, thrs, bias, dbsn, dbsd )
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