[Gvsig_english] Visibility analysis

[Angus Jeffery]

Hi Antonio
Thanks for your reply. Very interesting despite my lack of Italian and I
can see some application for your research.
However, it's not quite what I meant - what I want to try to do is work out
which part of a defined site (I have a polygon) is least (or most) visible
from the surrounding landscape within a defined radius (I have raster of
elevation data). Any ideas?
Many thanks
Angus


On 24 September 2013 11:19, Antonio Falciano <afalciano at yahoo.it> wrote:

> 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
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