AWIPS character sets

Jim Ramer

Sep 1999

There are currently 5 different AWIPS character sets. Each character set can conceivably have 255 printable characters in it, although currently none of them have that many implemented. When displaying character data in AWIPS, the implementor must select one of these character sets to use, and then all text display calls will use that character set until it is changed. AWIPS character fonts are stroked fonts rather than bitmapped fonts--this is handy because they can be scaled arbitrarily rather than only by integral magnifications. The individual strokes are integer coordinates on a specific size matrix for each character set. Here is a list of these character sets:

 - Standard 7x9 ASCII. (Default)
 - Large 9x11 ASCII.
 - Weather Symbols (11x11).
 - Special Symbols (11x11).
 - Large Special Symbols (16x20).

In practice, the overwhelming majority of displays use only the default standard ascii character set. On the metar precip plot, amounts over .1 are plotted with the large ASCII character set. The two `special' symbols character sets are almost exclusively used for radar graphics. The weather symbols are used for the display of weather elements in metar plots. The file $FXA_HOME/data/metar_wx_symbols.dat controls the translation of metar weather strings by listing character sequences and the character code(s) in this character set to replace it with. The volume browser displays that are fields of icons can in theory use any of these character sets, though currently none of these types of displays uses anything but standard ASCII or weather symbols.

Here are displays that show the individual fonts available in each character set. These are shown with a stretch factor of 2, but without the line width increase typical of AWIPS character magnification, so that the individuals strokes can more easily be seen.

Standard ASCII

Large ASCII

Weather Symbols

Special Symbols

Large Special Symbols

Developers needing to design additional character displays can do so using the program `strokfont', which is built in the fontData directory. In that same directory are the files that contain the stroke data for each character set. The files are:

set 0     standard ascii          standard.bin
set 1     large ascii             afosascii.bin
set 2     weather symbols         afosfonts.bin
set 3     special symbols         font2syms.bin
set 4     large special symbols   largefont.bin