Thanks, I used GMT to interpolate the elevations of the extra points and it worked well. Just a quick question: When I use > xyz2grd <file.xyz> <assorted parameters> from the GMT package, it grids the surface using its own method, then using the new (from GMT) grid I find the elevations of the points that I am interested in (using GMT's grdtrack) and I end up with a file containing x, y and z coordinates which is what I wanted. If I import this file into OpenDX and plot the points together with the original data (gridded by OpenDX) using rubersheet, I will find that some of the points do not lay on top of the rubbersheet surface. Isn't it? So does this mean that If I want to be consistent I should export the data gridded by GMT?
Thanks a lot for your help. Jens > -----Original Message----- > From: [EMAIL PROTECTED] > [mailto:[EMAIL PROTECTED] Behalf Of Lloyd A > Treinish > Sent: 20 November 2002 04:08 > To: [email protected] > Cc: Jens Fernandez-Vega > Subject: Re: [opendx-users] Interpolating points > > If you are talking about constructing a surface, have you looked at Regrid > or Connect? Input is data on 2d coordinates (positions). Output has > connections. Regrid has new positions. Connect preserves the original > positions. Rubbersheet can operate on either output doing a > linear mapping > of the data to a 3d coordinate. Here's a very old paper that describes an > application of these ideas: > http://www.research.ibm.com/dx/proceedings/peru/index.htm or a couple of > MPEGs of the results: > http://www.research.ibm.com/people/l/lloydt/rainfall.mpg and > http://www.research.ibm.com/people/l/lloydt/peru_video.mpg > If memory serves, GMT had additional tools along these lines. You would > have to evaluate which methods would be more suitable. > > If you talking about determining the value at a point on the surface, > interactively, have you looked at Probe or Pick? > > > > Brent Wood <[EMAIL PROTECTED]>@opendx.watson.ibm.com on > 11/19/2002 04:16:24 > PM > > Please respond to [email protected] > > Sent by: [EMAIL PROTECTED] > > > To: Jens Fernandez-Vega <[EMAIL PROTECTED]> > cc: Opendx-Users <[email protected]> > Subject: Re: [opendx-users] Interpolating points > > > > > > On Tue, 19 Nov 2002, Jens Fernandez-Vega wrote: > > I suggest you install GMT (Generic Mapping Tools). I use this in > conjunction with OpenDX quite usefully. > > GMT uses netCDF grids as binary surface models. > > the command > > xyz2grd <file.xyz> <assorted parameters> > > will build a surface model representing your data, there are other > commands to do this as well (including surface, etc) to give control over > various aspects of the model. > > the command > echo "$X $Y" | grdtrack <parameters> > or > cat <file of x y values> | grdtrack <parameters> > > will return the interpolated value(s) at each X y location from the grid. > > > I'm using GMT to derive grids which are then used in OpenDX. GMT is also > Open Source. > > > > > I managed to create a Rubbersheet with the dx data, autocolor and find > the > > gradient of the surface. But now I would like to input the X and Y > > coordinates of some points and find out the corresponding Z value. Is > this > > possible? > > > > If somebody could point me to the past emails that could help or give > some > > hints or suggestions, it would be great. > > > Not a OpenDX based solution, but it will easily do what you want. > > > Cheers > > Brent Wood > > >
