vecfea -- Compute registration parameters for 1-D image using common image features.
vecfea reftable sectable column outtable
This task computes the parameters needed to register a "secondary" image file to the pixel coordinate scale of a "reference" file of vector data (spectra, time series, etc., with no independent variables) using two sets of features common to the files, identified in a "features table". The features table is an STSDAS table that contains the located points in the vector. This table could also be an ASCII table, such as the output from the rgcursor task in the IRAF lists package.
This task computes the parameters needed to specify the registration parameters from identical features identified in two vector (one-dimensional) data files.
The two features tables must be sorted in the same order to ensure that a given feature in the reference features file matches the corresponding feature in the secondary features file, e.g., element 432 in the reference features file must refer to the same feature as element 432 in the secondary features file. The two features files may contain different numbers of features, in which case, the smaller number of features will be used by vecfea.
The output table from this task may be used by the resamp task to resample the secondary file to the same scale and orientation as the reference file.
In the case of vectors, the output columns to the table are the coefficients c1 and c2 in the equation
X = c1 + c2*x
X is the position of a pixel in the reference vector and x is the position of the pixel in the secondary vector. Also, for informational purposes, there are two columns in the table that show the offset in X (DELTAX) and a magnification in X (XMAG).
- reftable [file name]
- Name of features table from the reference file.
- sectable [file name]
- Name of features table from the secondary file.
- column [string]
- Name of the pixel coordinate column in the features tables. The default value, c1, is the column name used for the first column of an ASCII table, which is the output from the rimcursor task. If another task is used to derive these positions and an STSDAS table is used, the name of the X coordinate column may be input here.
- outtable [file name]
- Name of the output registration table.
1. Derive the registration table reg.tab to resample the vector vector2.hhh with features table vec2.tab to the same scale and orientation as the vector vector1.hhh with features table vec1.tab. Both of the features tables are ASCII tables, with x-coordinates in column 1.
pl> vecfea reftable=vec1.tab sectable=vec2.tab column=c1 outtable=reg.tab
Type "help register option=sys" for a higher-level description of the register package.