[GRASSLIST:3608] Re: function to compare rasters visually

[Martin Wegmann]

Thanks Daniel,

I will try the script, pretty useful. I already know it from ERDAS and think 
that this function should be available per default in GRASS. But I was rather 
looking for a comparison of two rasters inside the same monitor. I think 
there does an equivalent function in ERDAS exist which name I forgot. 

Just to make it clear, raster 1 =  a; raster 2 = b

either with a moving border which is moved with the mouse across the monitor 

a a a a b b	a a a b b b
a a a a b b ->a a a b b b
a a a a b b     a a a b b b

horizontally or vertically. 
Which would be fantastic: A dynamic border which can be changed by moving the 
mouse in different directions (from vertical to horizontal to diagonal and 
anything in between) 

or two raster which dissolve and the strength of dissolving can be changed. 

- just raster 1 visible
- raster 1 80 % visible, raster 2 20% visible
- until raster 2 100% visible 


cheers Martin 


BTW did you or John already post this script as wish to be implemented in 
GRASS? 


On Monday 07 June 2004 14:19, Daniel Victoria wrote:
> Hi Martin,
>
> I had a similar problem once and John was kind enough
> to send me this script. It links to grass displays
> monitors so, whaever you look at in X0, X1 will
> follow, like linking the displays geographically in
> ERDAS.
> Hope it helps, but don't thanks me, thanks John
>
> Cheers
> Daniel
>
> --------------------------------------------------
> From:	"John Gillette" <JGillette at rfmd.com>
> To:	"Daniel Victoria" <daniel_victoria at yahoo.com>,
> "Sandro Klippel" <sandro.klippel at talha-mar.com.br>,
> "GRASSLIST" <grasslist at baylor.edu>
>
>
> try this:
>
> Select and then Erase x1 and then display what ever
> you want there.
> Select x0 and erase and display other info there.
>
> Run this script to either pan or zoom in x0.  After
> finishing
> the pan or zoom x1 will redraw it's contents at the
> same region
> thereby "following" what ever is done in x0.
>
> The disadvantage is that you can only do 1 pan or zoom
> at a time,
> i.e. not interactively.
>
> usage:
>
> script_name z   <- does zoom instead of pan
> script_name
>
> zooming and panning in x0.  x0 is selected at exit.
>
> Does this help?
>
> John
>
> ------------------
> #!/bin/sh
>
> d.mon select=x1
> monitor1=`d.save -o`
>
> d.mon select=x0
> if [ "$1" = "z" ]
>  then
>    d.zoom
>  else
>    d.pan
> fi
> region=`g.region -g`
>
> d.mon select=x1
> d.erase
> g.region $region
> eval "$monitor1"
>
> d.mon select=x0
>
> exit 0
>
> --- Martin Wegmann <mailinglist2_wegmann at web.de>
>
> wrote:
> > Hello,
> >
> > I was looking for a function which makes it easy to
> > compare two images
> > visually by dissolving the upper image or only
> > displaying parts of the upper
> > image and moving the border between upper and lower
> > image across the monitor.
> > In other programs it is called dissolve or flicker.
> > But I couldn't find
> > anything related to this by using the GRASS search
> > function.
> >
> > Thanks for pointing me to the correct word in GRASS.
> > Martin
>
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