[R-sig-Geo] Create Kernel image results in *tif format

[Ege Rubak]

Dear Alexandre,

Indeed the solution by Florian below is very nice. If you really want to 
go the other direction you can use `as.SpatialGridDataFrame.im()` from 
the `maptools` package.

By the way, based on what you write, I think you mean to use the value 
7.5 (=0.75m) rather than 0.75 (=0.075 m) for your kernel bandwidth. 
Furthermore, the argument to set the standard deviation of the 
(isotropic Gaussian) smoothing kernel in `density.ppp()` is `sigma`, so 
you probably want:
     d_pines <- density(swedishpines, sigma = 7.5)

If you like to work in meters rather than decimeters you can rescale the 
point pattern:
     pines <- rescale(swedishpines, s = 10, unitname = "m")
     d_pines <- density(pines, sigma = 0.75)

Regards,
Ege


On 09/27/2018 10:01 AM, Florian Betz wrote:
> Dear Alexandre,
> 
> instead of converting the image to a SpatialPixelDataFrame converting to 
> a raster object might be an alternative.
> 
> r_pines<-raster(d_pines)
> writeRaster(r_pines, "Pines.tif")
> 
> Regards,
> Florian
> 
> Am 26.09.2018 um 22:25 schrieb ASANTOS via R-sig-Geo:
>> Dear R-sig-geo Members,
>>
>>       I've like to create Kernel image results as *tif using an object of
>> density() function output in spatstat package. But in my example,
>> doesn't work when I try:
>>
>> #Packages
>> library(spatstat)
>> library(raster)
>> library(rgdal)
>>
>>
>> #Swedishpines's data set in spatstat package
>> data(swedishpines)
>> plot(swedishpines)
>>
>> #CSR with K-Ripley test
>> csr_pines <- envelope(swedishpines, Kest, nsim=99)
>> plot(csr_pines)
>> # r=0.75 is outside CSR
>>
>> #Kernel representation using 0.75 as bandwidth
>> d_pines<-density(swedishpines, bw=0.75)
>> plot(d_pines)
>>
>> #Create TIFF image
>> r_pines <- as(d_pines, "SpatialPixelsDataFrame")
>> writeGDAL(r_pines, "Pines.tif")
>> #
>>
>>> r_pines <- as(d_pines, "SpatialPixelsDataFrame") Error in as(d_pines,
>> "SpatialPixelsDataFrame") : no method or default for coercing “im” to
>> “SpatialPixelsDataFrame”
>>
>> Please any ideas for corrected this?
>>
>> Thanks in advanced,
>>
>> Alexandre
>>
>