[GRASS-user] Resampling with percent cover

[Ned Horning]

Glynn,

Very nice solution! Thanks. I'm somewhat embarrassed I didn't think of 
that.

Ned

Glynn Clements wrote:
> Ned Horning wrote:
>
>   
>> Hi � I am still working on creating a percent shrub cover map using GRASS
>> and R and have a question regarding resampling. I have
>> shrub/non-shrub/cloud maps at 1m resolution and I want to resample those
>> to 30m pixels using the following logic.
>>
>> The value of each output 30m pixel will be the percentage of shrub pixels
>> that make up the corresponding 30 x 30 pixel area from the
>> shrub/non-shrub/cloud map and if any of the pixels in the 30 x 30 pixel
>> area has a cloud value the value of the resulting 30m pixel will be NULL.
>>
>> Is there a way to do this in GRASS? R.resamp.stats seems like it is close
>> but that might be too difficult for me to modify.
>>     
>
> There shouldn't be any need to modify it.
>
> Create a reclass of the input such that shrub=1, non-shrub=0 and
> cloud=null, then resample that with "r.stats -n method=average ...".
>
> The value of each output cell will be the proportion of shrub cells in
> the corresponding 30x30 block of input cells, in the range 0.0 to 1.0
> (if you want 0-100, use r.rescale or r.mapcalc). With the -n flag, if
> one or more of the input cells in a 30x30 block are null, the
> corresponding output cell will be null.
>
>