title: R: how to create raster layer from an estUDm object
body: <p>I've created Kernel home ranges from gps locations using the tool kernelUD from the package(adehabitatHR) using the code:</p>
  
  <pre><code>'udKerHref &lt;- kernelUD(data[,1],h = "href", grid=100, kern = c("bivnorm"))'
  </code></pre>
  
  <p>where data is a SpatialPointsDataFrame from 10 animals. I would now like to do two things:</p>
  
  <ol>
  <li>create a raster from the Kernel density values which I can multiply with another raster (Resource selection function raster)</li>
  <li>intersect other gps locations not used for building the home range with the raster built in 1 to extract the raster value at the given gps location</li>
  </ol>
  
  <p>I tried to use the function 'estUDm2spixdf(x)' but I get the error</p>
  
  <pre><code>'Error in estUDm2spixdf(udKerHref) : this function can be used only when the same grid was used for all animals'
  </code></pre>
  
  <p>even though I used the same gris for all animals. And I also tried to get the raster using 'getVolumeUD and then export the object using 'writeRaster'. But I always got an error</p>
  
  <pre><code>'Error in (function (classes, fdef, mtable)  :unable to find an inherited method for function ‘writeRaster’ for signature ‘"estUD", "character"’'
  </code></pre>
  
  <p>Any help is most appreciated</p>