# Re: units of gsMarkerSizeF?

From: Carl J. Schreck, III <carl_at_nyahnyahspammersnyahnyah>
Date: Wed, 27 Aug 2008 13:51:39 -0400

I wonder if it is a throw-back to ncar graphics? I've copied the
relevant part from the documentation of plchhq in ncar graphics
(http://ngwww.ucar.edu/supplements/plotchar/). A quick test shows
that you can also use the negative values that it mentions in ncl,
too. Not sure how much it clarifies things, but I thought I'd throw
it out there.

Cheers,
Carl

SIZE specifies the desired character size. If the internal parameter
'MA' is zero, then the following comments apply:

* If SIZE is less than or equal to zero, its absolute value
specifies the size as a multiple of the digitized size. On a 1024x1024
grid, principal-size capitals are about 'PW' units wide by 'PH' units
high and the vertical spacing between lines is 'PV' units (by default,
'PW', 'PH', and 'PV' are 16, 21, and 32). Indexical-size capitals are
'IW' units wide by 'IH' units high and the vertical spacing between
lines is 'IV' units (by default, 'IW', 'IH', and 'IV' are 12, 13, and
20). Cartographic-size capitals are 'CW' units wide by 'CH' units high
and the vertical spacing between lines is 'CV' units (by default,
'CW', 'CH', and 'CV' are 8, 9, and 14).

Example: Using CHRS = 'ABC' and SIZE = -2. will write three
characters, each of which is about 32/1024 of the plotter frame in
width.

* If SIZE is greater than zero, but less than one, it specifies
the desired approximate width of a principal-size capital as a
fraction of the distance across the plotter frame. This is the
recommended scheme.

Example: Using CHRS = 'ABC' and SI ZE = .05 will write three
characters, each of which is about 5 hundredths of the plotter frame
in width.

* If SIZE is greater than or equal to one, it specifies the
desired approximate width of a principal-size capital in plotter
coordinates, as defined by default or by a user call to the SPPS
routine SETI. Note that use of the routine SETI is now discouraged.

Example: Using CHRS = 'ABC' and SIZE = 13. (assuming there have
been no calls to the SPPS routine SETI) will write three characters,
each of which is about 13/1024 of the plotter frame in width.

On Wed, Aug 27, 2008 at 10:10 AM, Mary Haley <haley_at_ucar.edu> wrote:
> Leslie,
>
> You are right, the documentation is inconsistent. I myself
> use values like 10.0 for this resource. I'm looking into this
> to get an explanation, but meanwhile, assume that the units
> are not NDC coordinates.
>
> --Mary
>
> On Tue, 26 Aug 2008, Leslie Hartten wrote:
>
>> The online documentation of gsMarkerSizeF says it specifies the size in
>> NDC units, and has a default=0.007. My understanding is that NDC units run
>> from 0.0 to 1.0. However, the first example of using poly markers
>> (www.ncl.ucar.edu/Applications/Scripts/polyg_3.ncl) shows the resource
>> fsMarkerSizeF set = 5.0. How can this be?
>>
>> Cheers,
>> Leslie
>> _______________________________________________
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Received on Wed Aug 27 2008 - 11:51:39 MDT

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