Rotating with maptools::ellide()
Roger,
On Sat, Dec 15, 2012 at 11:06 PM, Roger Bivand <Roger.Bivand at nhh.no> wrote:
On Sat, 15 Dec 2012, Agustin Lobo wrote:
Given an SpPolDF, if I rotate the first polygon with delme <- elide(testAlfacs20120626footp[1,], rotate=-90) I get the result shifted. I get the rotation I was expecting by indicating the coordinates of the center: delme <- elide(testAlfacs20120626footp[1,], rotate=-90,center=coordinates(testAlfacs20120626footp[1,])) How could I rotate all polygons, each one around its own centroid? I've tried
delme <- elide(testAlfacs20120626footp, rotate=-90,center=coordinates(testAlfacs20120626footp))
Error in .local(obj, ...) : center must be numeric of length two
Plrease provide a motivation - elide methods are not intended to elide parts of data sets.
My polygons are rectangles that represent the ideal footprints of aerial images acquired from a UAV. I want to rotate in order to visualize different positions of the camera in the UAV.
Please also provide the code for copy and paste, withou having to discard the leading prompts. If you need a different function, why not write one as a loop over elide - although then there will be absolutely no chance that your output geometries will be planar, so things like plotting just will not work as expected where entities overlap.
Yes, a loop is the obvious solution, I just thought ellide() would actually provide the option of individual rotation by providing on center point of rotation for each polygon. Thanks Agus