[GRASSLIST:3616] Re: function to compare rasters visually

[Glynn Clements]

Martin Wegmann wrote:

> 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) 

The main issue is likely to be whether this can be done fast enough
for interactive use. In that regard, the vertical case (i.e. a
horizontal border which can be moved vertically) would be the most
feasible.

> 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 

As I've noted in another post, you would essentially have to perform
the entire process in software then send the result to the driver. 
That isn't likely to be fast.

-- 
Glynn Clements <glynn.clements at virgin.net>