Re: shakey in hammer projection

[Ansley Manke <ansley.b.manke@xxxxxxxx>]

Hi everyone,
There is already an FAQ covering much of this topic,

How can I get the right aspect ratio for map projections in viewports?
http://www.ferret.noaa.gov/Ferret/FAQ/graphics/mp_viewport_aspect.html



Ansley Manke wrote:

> Hi Boyin,
> This involves the interaction of the map projection and the size of
> the viewport.  If you call mp_aspect this sets the aspect ratio of the
> entire window.  If you also define a viewport, the dimensions that you
> give to the viewport also sets the ratio of the horizontal and 
> vertical axes.
> The viewport is more flattened than the aspect ratio that mp_aspect
> computes.
>
> Then when you make a shade or fill plot, with Ferret determining  the 
> size
> of the shade key  automatically, the key can seem to disappear in a small
> and flattened viewport. 
> See what the mp_aspect.jnl script is doing with
>   yes?  go/help mp_aspect
>
> You should probably set your data and the region, call mp_hammer, set the
> grid, then do
>
> yes? go mp_aspect LIST
>
> The script computes the appropriate aspect ratio for the projection and
> the region.  Use the result to define the viewport.  Define the viewport
> with the /AXES qualifier to accurately set the correct ratio of the
> axis lengths.  Here is an example.  I think I will make this into an
> FAQ as it's an interesting detail that should be documented.
>
>  yes? can mode logo
>
>       ! Start with a window having a known aspect ratio of 1.
>
>  yes? set win/asp=1
>
>  yes? can mode logo
>  yes? use coads_climatology
>  yes? go mp_hammer
>  yes? set grid sst
>
>       ! Set the variable y_over_x to use in
>       ! setting the viewport.
>
>  yes? go mp_aspect LIST
>
>       ! Define the relative lengths of the axes,
>       ! as a proportion of the entire window.
>       ! Because we started with an overall aspect
>       ! ratio of 1, the viewport axis ratio will
>       ! be set by y_over_x
>
>       ! The numbers 0.1, 0.45 and 0.65 are arbitrary,
>       ! setting the desired location of the viewport.
>
>  yes? let xlen = 0.45-0.1
>  yes? let ylen = xlen*y_over_x
>  yes? define view/axes/xlim=0.1,0.45/ylim=0.65,`0.65+ylen` v1
>
>       ! Shade with automatic shade key
>
>  yes? set view v1
>  yes? shade/noax sst[l=1], x_page, y_page
>
>       ! In a second window, put the shade key horizontally
>       ! above the plot.
>
>  yes? define view/axes/xlim=0.1,0.45/ylim=0.15,`0.15+ylen` v2
>  yes? set view v2
>
>  yes? shade/noax/set sst[l=6], x_page, y_page
>  yes? let x1 = ($ppl$xorg)
>  yes? let x2 = ($ppl$xorg)+($ppl$xlen)
>  yes? let y1 = ($ppl$yorg)+($ppl$ylen)+0.8
>  yes? let y2 = ($ppl$yorg)+($ppl$ylen)+1.1
>  yes? ppl shakey 1,0,-0.1,,,,`x1`, `x2`, `y1`, `y2`
>  yes? ppl shade
>
>
> The third argument to the shakey command puts the labels on
> the upper side of the shade key so they are easier to read.
>
>
> Boyin Huang wrote:
>
> > ferreters:
> >
> > I notice the following problems in the color legend
> > (ppl shakey in fill plot) for hammer projection map:
> >
> > (1) if mp_aspect is not used, the legend can only be
> > put horizontally, not vertically (not appear).
> >
> > (2) when a small view port is used (def 
> > view/xlim=0.09,0.49/ylim=0.69,0.90  v1),
> > the horizontal legend disappeared again.
> >
> > if a large view port (def
> > view/xlim=0.15,0.85/ylim=0.69,0.90  v1) is set, the horizontal legend 
> > is fine.
> >
> > Can we make the lengend to appear in a small plot? Can
> > we put the legend in vertical direction without using
> > mp_aspect?
> >
> > Thank
> >
> > =====
> > Boyin Huang
> > The Center for Research on the Changing Earth System (CRCES)
> > 10211 Wincopin Circle, Suite 240
> > Columbia, Maryland 21044
> > Tel. 410-992-5300/19 (O), 410-461-9339(H) Fax. 410-992-5944, Email. 
> > byh@crces.org http://byh.crces.org
> >
> >
> >        
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