[R-sig-Geo] Ideas on qualifying urban shapes: linear / circular / star

[Sarah Goslee]

Hi,

On Fri, Sep 30, 2011 at 5:21 AM, Mathieu Rajerison
<mathieu.rajerison at gmail.com> wrote:
> Hello list,
>
>
> I have determined major urban areas.
>
> This is just a post to get ideas from R-users on how to qualify urban
> shapes.
>
> The data can either be binary raster (urban/ not urban), either vector.
>
> 1) Some urban areas follow linear infrastructures, thus are linear
> 2) Some other diverge equally from a central heart, and are circular.
> 3) Some are a mix and are like stars.

That sounds like the kind of task that patch metrics such as perimeter/area
ratio and fractal dimension were created for. Take a look at the copious
Fragstats literature. I don't know if any have been implemented in R, but
wouldn't be surprised.

Sarah

> The idea would be to get an index that give for each area, the probability
> of belonging to each of these three classes. Like a 3-column data frame
>
> I wondered if packages already existed, or statistical methods for this
> purpose. Notably, I think that topographic derivatives derived from
> smoothed/unsmoothed binary data like aspect, could be used to qualify these
> shapes (?)
>
> Thanks for any idea or exchange on the subject!
>


-- 
Sarah Goslee
http://www.functionaldiversity.org