[GRASS-dev] v.perturb

[Alessandro Samuel Rosa]

The place where a point will fall depends on the arguments "distribution" and "parameters". In spatial simulated annealing we start allowing a point to be shifted (perturbed) to any location within the study area. As the iterations go on, we constrain the amount of shifting to shorter distances.

Regarding v.random: could you please include a description in the help page on how the restriction is done? This is an extremely important information.

 
Alessandro Samuel-Rosa 
--- 
Graduate School in Agronomy - Soil Science 
Federal Rural University of Rio de Janeiro 
Seropédica, Rio de Janeiro, Brazil 
--- 
Guest Researcher at ISRIC - World Soil Information 
Wageningen, the Netherlands 
--- 
Homepage: soil-scientist.net   Skype: alessandrosamuel


Em Quinta-feira, 28 de Agosto de 2014 17:28, Markus Neteler <neteler at osgeo.org> escreveu:
 



On Aug 27, 2014 12:12 AM, "Alessandro Samuel Rosa" <alessandrosamuel at yahoo.com.br> wrote:
>
> Dear GRASS GIS developers,
>
> I am planning to use v.perturb to run a spatial simulated annealing exercise. Two drawbacks with v.perturb exist. First, "output vector points are not guaranteed to be contained within the current geographic region".
The command v.random got recently improved to optionally constrain points being generated to a restricted area. Not sure if this method could be implemented here as well.
Did you test how far outside points may fall?
> Second, all vector points are perturbed together.
Here a "where" statement would help, to be implemented...
Markus
> Is it very difficult to solve this issues?
>
> Another option for perturbation would be v.edit, but in that case the direction and distance are not random.
>
> Best,
>  
> Alessandro Samuel-Rosa 
> --- 
> Graduate School in Agronomy - Soil Science 
> Federal Rural University of Rio de Janeiro 
> Seropédica, Rio de Janeiro, Brazil 
> --- 
> Guest Researcher at ISRIC - World Soil Information 
> Wageningen, the Netherlands 
> --- 
> Homepage: soil-scientist.net Skype: alessandrosamuel
>
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