Thanks for the kind comments... Yes, Greg's trick could be useful here. It's a good one that I had forgotten about. (I haven't dealt with global-scale data in a long time). It's not unlike what I had suggested except it has the advantage of creating a simple field instead of a multigrid. Then one could use some of my old map projections macros as is. Depending on the data, the seam may or may not be visible. The mesh will be connected, but discontinuity in the data on either side of the seam will still be there, which is the right thing to have.
But the paramount issue, as you suggest, is how are the data defined. These tricks may resolve visual artifacts, but not necessarily the data issues. Chris Pelkie <[EMAIL PROTECTED]>@opendx.watson.ibm.com on 12/19/2000 08:02:08 AM Please respond to [email protected] Sent by: [EMAIL PROTECTED] To: [email protected] cc: Subject: Re: [opendx-users] How control layers? I defer to Lloyd's vastly superior understanding and explanation of the problem. But, you might find this trick useful (Greg Abram originally told me about it): Given the 2D field (regular mesh topology) you want joined edge to edge (let's say in the 0 dimension: this need not be X in DX speak, but let's assume it is): slices = Slab(2dfield, thickness=0, dimension=0, position=(all)); slice0 = Slab(2dfield, thickness=0, dimension=0, position=0); sliceset = CollectSeries(slices, 0, slice0, 1);//order of arguments matters! cylindermesh = Stack(sliceset, dimension=0); Then do the spherical projection on cylindermesh. Viewing the 2D output will have long lines that cut across the surface, but after the projection the seam will be gone. Whether or not this changes the weather is up to you to determine. (:-). Poles are not joined, of course. a. The trick is Slabbing all with thickness 0 produces a 'series' object of 2D slices (without interpolation) from the position-dependent field. Then you copy the 0th slice and append it to the series. Stack makes a new 2D field with one additional column. b. The trick does not work with connection-dependent data. Chris Pelkie Vice President/Scientific Visualization Producer Conceptual Reality Presentations, Inc. 30 West Meadow Drive Ithaca, NY 14850 [EMAIL PROTECTED]
