<br><br><div class="gmail_quote">On Wed, Dec 16, 2009 at 7:19 PM, Giovanni Manghi <span dir="ltr"><<a href="mailto:giovanni.manghi@gmail.com">giovanni.manghi@gmail.com</a>></span> wrote:<br><blockquote class="gmail_quote" style="border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt 0pt 0.8ex; padding-left: 1ex;">
Viva,<br>
<div class="im"><br>
<br>
> > Estou a precisar construir um raster através da ferramenta de Kernel<br>
> > Density baseada numa layer de pontos e num dos seus atributos. Já<br>
> > estive a experimentar no gvSIG+Sextante e o resultado não me<br>
> > satisfaz uma vez que só me aceita pixel de 1000 metros. Se diminuir<br>
> > este parâmetro tenho problemas com Java Heap Space (memória). Fui ao<br>
> > grass dentro do qgis e vejo la a função gaussian kernel mas não<br>
> > permite seleccionar um atributo do vector. Alguém tem sugestões???<br>
> ><br>
> > Obrigado.<br>
</div>> > Abraço Viva,<br>
<br>
<br>
<br>
no QGIS poderá usar o plugin<br>
"SDA4PP" (Spatial Data Analysis for Point Pattern) que, entre as outras,<br>
inclui as seguintes ferramentas:<br>
<br>
<br>
* Interactive Identify Tool: returns the value of<br>
overlapping raster and vector layers at the same<br>
time in one window. It gives more information<br>
about feature than the standard identify tool in<br>
QGIS.<br>
* Quadrat analysis: A method of point pattern<br>
analysis in which the study region is sampled<br>
using a set of similar shapes (quadrats) and<br>
counting the number of events in each. Analysis<br>
of the resulting quadrat counts can help<br>
determine whether the pattern is evenly spaced<br>
or clustered.<br>
* F function: A function in point pattern analysis<br>
based on the cumulative frequency of the<br>
shortest distance between events in a point<br>
pattern and a set of randomly placed locations<br>
in the study area.<br>
* G function: A function in point pattern analysis<br>
based on the cumulative frequency of the<br>
shortest inter- event distances between events<br>
in a point pattern.<br>
* K function: A function in point pattern analysis<br>
based on all the inter-event distances between<br>
events in a point pattern.<br>
* Kernel density estimation: A method of density<br>
estimation making use of kernel functions. For<br>
each event to be included in the density<br>
estimates a kernel function is used to 'spread'<br>
its effect across space.<br>
<br>
<br>
<a href="http://ggit.metu.edu.tr/%7Evolkan/screenshots.html" target="_blank">http://ggit.metu.edu.tr/~volkan/screenshots.html</a><br>
<br>
Para o plugin funcionar é necessario instalar o pacote estatístico "R" e<br>
algumas suas bibliotecas adicionais.<br>
<br>
Saluti<br>
<br>
--<br>
Giovanni Manghi<br>
Faunalia.pt<br>
Sistemas de Informação Geográfica Open Source<br>
Portugal<br>
<br>
Web: <a href="http://www.faunalia.pt" target="_blank">http://www.faunalia.pt</a><br>
Email & Jabber: <a href="mailto:giovanni.manghi@faunalia.pt">giovanni.manghi@faunalia.pt</a><br>
PGP Key available<br>
Tel. + 351 96 7058216<br>
<font color="#888888">--<br>
</font><br></blockquote></div><br>Para utilizar "SDA4PP" (Spatial Data Analysis for Point Pattern) é necessário intalar, entre outras coisas, <i>python-rpy2</i> e depois os pacotes de R <i>sp</i>, <i>rgdal</i>, <i>maptools</i>, <i>spatstat</i>. Acontece que nao consigo instalar <i>spatstat</i>, da-me:<br>
<br>> install.packages("spatstat", dependencies=TRUE)<br>Warning in install.packages("spatstat", dependencies = TRUE) :<br> argument 'lib' is missing: using '/home/eloi/R/x86_64-pc-linux-gnu-library/2.9'<br>
--- Please select a CRAN mirror for use in this session ---<br>Loading Tcl/Tk interface ... done<br>Warning message:<br>In getDependencies(pkgs, dependencies, available, lib) :<br> package ‘spatstat’ is not available<br>
<br>Alguma ideia do porque? Estou com Ubuntu 9.10.<br clear="all"><br><br>-- <br>Eloi Ribeiro<br>GIS Analyst<br>39.45º -4.40º<br><a href="http://eloiribeiro.wordpress.com">http://eloiribeiro.wordpress.com</a><br>