Program: SNAPPER Purpose: Replace values by a box with other values e.g. for removing a bad perimeter of a velocity field. Category: MANIPULATION, UTILITY, VELOCITY-FIELDS File: snapper.c Author: M.G.R. Vogelaar Keywords: INSET= Give input set (,subsets) to process: Maximum number of subsets is 2048. This set will be transformed to OUTSET= after replacing certain values by other values. BOX= Give box in ..... [entire subset] Restrict operations to data within these limits. OUTSET= Give output set (, subsets): Output set and subset(s) for the result. The number of output subsets is the same as the number of input sub- sets. OLDVAL= Which map value do you want to replace? [blank] All values OLDVAL= in the input set will be replaced by NEWVAL= Also its neighbours in a box with size REPSIZE= get the new value. NEWVAL= What is the new value? [blank] This is the new value in OUTSET= which replaces OLDVAL= in the input set. REPSIZE= Size of replace box: [3 3] Not only the pixel with OLDVAL= is replaced but also its neighbours in a box with sizes in x and y direction as defined in this keyword. If one selects REPSIZE=1 1 then you have the functionality of program CBLANK. Notes: ....... Example: ....... Description: Suppose you have a velocity field with a perimeter defined by a blank and a non-blank pixel and the values in your perimeter are results of a poor fit. To remove such values by hand can take a long time. This program searches for values given in OLDVAL= and replaces them by values entered in NEWVAL= in a box in the output set with sizes entered in REPSIZE= and centered at the position of the corresponding value in the input set. In the default configuration, this program replaces one blank by 9 blanks in a box with size 3 x 3 pixels, thereby effectively 'eating' the blank/ non-blank perimeter of any object in the input map. Updates: Sep 01, 1998: VOG, Document created.