rtilt

From DavinciWiki

Contents: Description, Arguments, Usage, Examples, Images, Sub-Functions, Related Functions, Source

Description

Perform a running remove tilt on every xy plane of the data (band independent). This process must be performed on either rectified or RDR data.

rtilt() performs an individual removal of tilt on every sub-section of the array defined by an x and y dimension. It then uses an overlap of half of the defined size to blend it with the next section of the data. This is done so there is no visible seam and the tilt removal is esentially "running" or changing over the whole data set. This process helps eliminate tilt which is variable over the length of the image (especially in long images). The removal effect is evident when looking at the sample images below.

Changing the y size will ultimately determine how much small or large variation of tilt can be removed.

Arguments and Return Values

Arguments: Accepts any numeric array (RDR or rectified data is required)

Return Value: A float array

Usage

Syntax: rtilt(data = VAL [, ignore = FLOAT] [, ysize = INT] [, verbose = INT][, yavgonly = BOOL][, xsize = INT])

'data' - Any numeric array

'ignore' - Ignore value of the black space. Default of -32768.

'ysize' - Any integer for breaking up the data in the y direction. Default of 1000.

'verbose' - print the segment of the image that is being manipulated. Default is 0.

'xsize' - size of the filter in x (Default is 100)

'yavgonly' - subtract the y-average and add back the average (Default is 0)

Examples

dv> a
339x10923x10 array of float, bsq format [148,115,880 bytes]

The two methods below are equivalent and yeild the same results, but the second can be used for more memory efficient processing.

dv> b = rtilt(a, ignore = -32768)
339x10923x10 array of float, bsq format [148,115,880 bytes]

dv> b = rtilt(data = a, ignore = -32768)
339x10923x10 array of float, bsq format [148,115,880 bytes]

Images

The image on the left first shows the tilt as a bright blue color which later changes in the image to a green color. The right image has had rtilt() applied.