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

[Sarah Goslee]

Mathieu,

On Fri, Sep 30, 2011 at 9:24 AM, Mathieu Rajerison
<mathieu.rajerison at gmail.com> wrote:
> Hi,
>
>
> Maybe you're right: perimeter/ratio could be sufficient...
>
> Fractal dimension and lacunarity are good indicators for urban areas. Do you
> know any R package, tool to quantify these?

I've always just used Fragstats, as I already suggested, but you might look into
SDMtools:
http://cran.r-project.org/web/packages/SDMTools/
http://mo-seph.com/node/302

Sarah

> I have found an ImageJ plugin called Fraclac.
>
> There is another one called r.lacunarity included in spatialtools
> http://www.clusterville.org/spatialtools/index.html
> r.lacunarity is interesting compared to ImageJ::Fraclac because it uses a
> moving window and generates a raster.
>
> I launched a post about lacunarity and fractal dimension on R but didn't
> have any answer.
>
>
> So, if anyone manages to use r.lacunarity or knows other tools than Fraclac,
> I'd be happy!
>
>
> For those interested , here is some literature on fractal dimension applied
> to analysis or aerial images or cities:
> http://www.public.asu.edu/~smyint/publications/CEUS-Lacunarity-Myint-Lam.pdf
> http://cybergeo.revues.org/8902
> http://www.isprs.org/proceedings/XXXVII/congress/3b_pdf/80.pdf
> http://www.fatih.edu.tr/~mcadams/geo352/fractal.pdf
>
>
> 2011/9/30 Sarah Goslee <sarah.goslee at gmail.com>
>>
>> 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