Any news on this? I'm having a similar problem. In addition, kernel.area(x,percent=c(50,95),unout="m2",standardize=F) provides different area values when compared with those obtained by using getverticeshr(kudvej, 95,unout="m2") -- View this message in context: http://r-sig-ecology.471788.n2.nabble.com/problem-with-kernel-UD-estimation-using-adehabitatHR-tp7578930p7579498.html Sent from the r-sig-ecology mailing list archive at Nabble.com.
problem with kernel UD estimation using adehabitatHR
3 messages · André Zehnder, dmaa
Hi dmaa, I got this error when I used too low grid values to quickly checked the results. Try different values for the "grid" parameter (e.g. grid=450). In addition, the extent values of alittle seem to be rather high. As I understand it (and please correct me if I am wrong), the extent is a factor that defines by how much percent of the range of coordinates included in a dataset is extended, so that the UD is not cut off too early. For example: If the bounding box around your coordinates is 300x300 km, a extent of 0.1 would expand this area by 10% (in total 330x330 km). Therefore, unless you have enormously high smoothing parameters and/or tiny home ranges to expect, extents of 0.1?0.5 will be enough. About the area issue: Are the differences large or so small that they are negligible and possibly only a result of different precisions? Another reason could be that one of the two methods considers holes and subtract their areas while the other does not. Best regards, Andr? -----Urspr?ngliche Nachricht----- Von: R-sig-ecology [mailto:r-sig-ecology-bounces at r-project.org] Im Auftrag von dmaa Gesendet: Montag, 13. Juli 2015 13:48 An: r-sig-ecology at r-project.org Betreff: Re: [R-sig-eco] problem with kernel UD estimation using adehabitatHR Any news on this? I'm having a similar problem. In addition, kernel.area(x,percent=c(50,95),unout="m2",standardize=F) provides different area values when compared with those obtained by using getverticeshr(kudvej, 95,unout="m2") -- View this message in context: http://r-sig-ecology.471788.n2.nabble.com/problem-with-kernel-UD-estimation- using-adehabitatHR-tp7578930p7579498.html Sent from the r-sig-ecology mailing list archive at Nabble.com. _______________________________________________ R-sig-ecology mailing list R-sig-ecology at r-project.org https://stat.ethz.ch/mailman/listinfo/r-sig-ecology
2 days later
Hi Andr?, Your suggestion on grid parameters helped. I played with grid and extent and found nice solutions. Thanks! After reading the package pdf I have found that "Note that the home-range sizes returned by this function are slightly different from the home-range size stored in the SpatialPolygonsDataFrame returned by the function getverticeshr . Indeed, while the former measures the area covered by the rasterized home range (area covered by the set of pixels of the grid included in the home range), the latter measures the area of the vector home range (with smoother contour). However, note that the difference between the two estimates decrease as the resolution of the grid becomes finer" Cheers, David -- View this message in context: http://r-sig-ecology.471788.n2.nabble.com/problem-with-kernel-UD-estimation-using-adehabitatHR-tp7578930p7579513.html Sent from the r-sig-ecology mailing list archive at Nabble.com.