As a quick followup:
I worded question #1 poorly. I was wondering if the IBM Copyright should
be replaced, but taking a second look, I believe the copyright is for
"Open Visualization Data Explorer". In any case, should
that same copyright/license be placed at the top of the program?
Another question I meant to ask was: Should the module even be added to
CVS? I can certainly make it available through the Univ. of Montana site.
Lastily, you can ignore my comment on skew grids, I am now using
(what I consider) the best method for determining where to place the
scattered data on the grid.
Jeff
On Tue, 9 Jan 2001, Jeff Braun wrote:
> I have been working on generalizing a module that I developed a couple of
> years ago in order to add it to OpenDX. The much improved version is about
> ready to go, but a couple of questions came up before adding it to CVS.
>
> 1) Should the same license agreement be put at the top of the code? Can
> I just replace the IBM Copyright with my name?
>
> 2) How can I create a help file? I have not really looked into this, but
> any pointers would helpful.
>
> 3) What to name the module? (description below).
>
> 4) Anything else that needs to be considered?
>
> Jeff
>
>
> Scatter2Grid -
>
> I developed this module when a client had a 136x188x39 grid (nearly 1
> million points), but since all the grid points did not contain a
> data value, he output 153,000 data values as scattered data. Attempts to
> use the Regrid module on a multiprocessor SGI (Onyx?) were very slow
> especially considering that the data originated on a grid. So I developed
> a module to look at each scattered postion and put its data value into the
> grid data array, with a null value assigned to those grid points without a
> data point. Thus I called the module Scatter2Grid. For this data
> set I estimated this module ran on the order of 1 million times faster
> than using the Regird module.
>
> The first version was rather crude, but I have added several features
> through the years, which include:
>
> 1) Position and connection dependent grid option
> 2) Binning - if more than one value are located in the same cell, then the
> average value is computed.
> 3) Vector data and all data types but double can now be used, originally
> just scalar float data worked.
>
> The module does not do any interpolation, so if there is no data value
> within 1/2 delta length of the position (or within a cell for connection
> dependent grid) then a null value is assigned. Thus it does not work for
> sparse data, but in that case the Regird module should work fine. It only
> works for grids with element type quads or cubes.
>
> Currently, I have two alogorithms to convert the scattered positions into
> grid data array index number. The current version does not work with a
> skew grid (e.g. delta {[5,-5],[1,8]}). The other algorithm does not allow
> the z axis to vary from vertical, i.e. the delta must be of the form
> {[a.x,a.y,0],[b.x,b.y,0],[0,0,z]}, but it works for x,y skew grids.
>
> How important is working with skew grids?
>
> I am currently looking at extending the second algorithm. Otherwise some
> simple tests can be used to determine which method to use.
>
> Any comments would be appreciated.
>
>
>
>
>
>
>
----------------------------------------------------------------------
Jeff Braun Geophysics Dept.
mailto: [EMAIL PROTECTED] Montana Tech
(406) 496-4206 1300 W. Park St.
Butte, MT 59701
