[Gvsig_english] Visibility analysis

[Antonio Falciano]

Il 24/09/2013 11:48, Angus Jeffery ha scritto:
> Hello
> I am doing some visibility analysis work in gvSIG. I often use the grass
> r.cva process and various of the sextante visibility tools for standard
> viewsheds. I would like to work out how to do a 'reverse viewshed',
> whereby the output is a raster/heat map within a parcel of land, showing
> which areas are more or less visible from the surrounding area outside
> the parcel of land in the wider landscape. Does anyone have any ideas
> which tools to use and how to approach this most efficiently in gvSIG?
> Best regards
> Angus

Hi Angus,
"more or less visible" suggests me you are trying to compute the so
called "fuzzy viewshed", i. e. the degree of visibility between 0 and 1
of targets and vice versa. This kind of viewsheds are more sofisticated
than binary ones, which only say if a target is visible or not. The
logic consists into applying a fuzzy membership based on some physic law
to visibility and finally multiply the resulting raster with the
classical binary viewshed.
Some years ago [1] I reproduced them with SEXTANTE models (if I remember
well with SEXTANTE 0.6), but I'm not sure if all the tools involved in
this model are quite stable to do this work at the moment. Good luck!

Cheers,
Antonio

[1] http://slidesha.re/aaTMsa (in Italian, sorry!)

-- 
Antonio Falciano
http://www.linkedin.com/in/antoniofalciano