Date sent: Sun, 21 Sep 2003 15:50:49 +0200 (CEST) From: Roger Bivand <[EMAIL PROTECTED]> Send reply to: [EMAIL PROTECTED] To: Monica Palaseanu-Lovejoy <[EMAIL PROTECTED]> Copies to: [EMAIL PROTECTED] Subject: Re: [R] Z aware interpolation
Hi, Well, i guess i was not very clear. My points have x, y, z coordinates, and PAH concentration values. I need to do my interpolation for PAH taking into consideration all my x, y, z coordinates. Otherwise my data seems not to behave - which could be normal since the data points are not in the same plan. Besides, if i project the points into a XY plan ... the distance between points will change, points quite far apart in an xyz coordinate system can be very close into a projected XY system. So i need to work with "real" distances taking into consideration z values as well. Maybe there is an other way to do it in which z can be translated as a kind of "weight" for distance .... if i work only in a XY system. I don't know yet .... so i hope somebody will give me a clue. Thanks again, Monica On Sun, 21 Sep 2003, Monica Palaseanu-Lovejoy wrote: > Hello again, > > There is any package which does Z aware (real 3D) interpolations? > It can be any method (IDW, kriging or spline) but it should take into > consideration not only x and y coordinates for interpolation, but > also z coordinate. I looked into different packages but it seems i > didn't find the right one. Assuming that you have points with x and y coordinates, and a z attribute that you want to interpolate to a grid, then the akima package provides spline interpolation as interp(). See Chapter 15 in Venables and Ripley (2002) Modern Applied Statistics with S for more ideas. > > The ultimate goal is to import the output into a GIS (Geographical > Information System) for further analysis. > > Alternatively, maybe you know a source for codes for normal IDW > (Inverse Distance Weight) interpolation (i mean the one which > takes into consideration only x and y coordinates) so i can try to > modify it to take into consideration z values as well. I am not sure > it will work, or i can do it - but it worth a try - of course if this is not > already done. > > Thanks, > > Monica > > > Monica Palaseanu-Lovejoy > University of Manchester > School of Geography > Mansfield Cooper Building > Oxford Road, Manchester > M13 9PL, UK. > email: [EMAIL PROTECTED] > > ______________________________________________ > [EMAIL PROTECTED] mailing list > https://www.stat.math.ethz.ch/mailman/listinfo/r-help > -- Roger Bivand Economic Geography Section, Department of Economics, Norwegian School of Economics and Business Administration, Breiviksveien 40, N-5045 Bergen, Norway. voice: +47 55 95 93 55; fax +47 55 95 93 93 e-mail: [EMAIL PROTECTED] Monica Palaseanu-Lovejoy University of Manchester School of Geography Mansfield Cooper Building Oxford Road, Manchester M13 9PL, UK. email: [EMAIL PROTECTED] ______________________________________________ [EMAIL PROTECTED] mailing list https://www.stat.math.ethz.ch/mailman/listinfo/r-help
