Contouring a large set of ungridded data

John_Hunter · October 19, 2005, 2:50am

In any case, natgrid isn't Delaunay triangulation, but

    > natural neighbors interpolation which is better (and
    > probably state of the art for these kinds of graphics). It
    > might be easiest to contact Dave Watson and ask if we can
    > distribute his code in matplotlib under matplotlib's
    > license. I can't find any contact information for him,
    > however.

I'm all for this but am not optimistic. It's my understanding that
the NCAR folks are under a fairly heavy legal burden. Jeff: could you
spearhead this effort and see if there is any interest on their part
in relicensing their griddata code under a more permissive license?

JDH

Robert_Kern1 · October 19, 2005, 2:57am

John Hunter wrote:

"Robert" == Robert Kern <rkern@...376...> writes:

    > In any case, natgrid isn't Delaunay triangulation, but
    > natural neighbors interpolation which is better (and
    > probably state of the art for these kinds of graphics). It
    > might be easiest to contact Dave Watson and ask if we can
    > distribute his code in matplotlib under matplotlib's
    > license. I can't find any contact information for him,
    > however.

I'm all for this but am not optimistic. It's my understanding that
the NCAR folks are under a fairly heavy legal burden. Jeff: could you
spearhead this effort and see if there is any interest on their part
in relicensing their griddata code under a more permissive license?

It's not NCAR's code, it's Dave Watson's. NCAR got permission to
distribute the natgrid code under the GPL. We'd need to get independent
permission from Dave Watson to distribute the code under the matplotlib
license.

···

--
Robert Kern
rkern@...376...

"In the fields of hell where the grass grows high
Are the graves of dreams allowed to die."
-- Richard Harter

_Jeff_Whitaker1 · October 19, 2005, 11:31am

John Hunter wrote:

    > In any case, natgrid isn't Delaunay triangulation, but
    > natural neighbors interpolation which is better (and
    > probably state of the art for these kinds of graphics). It
    > might be easiest to contact Dave Watson and ask if we can
    > distribute his code in matplotlib under matplotlib's
    > license. I can't find any contact information for him,
    > however.

I'm all for this but am not optimistic. It's my understanding that
the NCAR folks are under a fairly heavy legal burden. Jeff: could you
spearhead this effort and see if there is any interest on their part
in relicensing their griddata code under a more permissive license?

JDH

John: I will do this and let you know. I agree with Robert on qhull - it's not the way to go. I did find this however:

http://www.marine.csiro.au/~sakov/

Bivariate spline-based techniques offer robust and efficient approximation solutions. Here `csa' (standing for "cubic spline approximation") is a small library for approximating 2D irregular (scattered) data with bivariate C1-continuous cubic splines <Forschung am Institut für Mathematik | Fakultät für Wirtschaftsinformatik und -mathematik | Universität Mannheim. For uniformly distributed data this algorithm is clearly superior than Natural Neighbours interpolation: it is faster (O(n)!), more robust (approximation, not interpolation) and better performing (C1!). (But take care when dealing with clustered data.) From version 1.09, `csa' can take advantage of the known variance of the data.

The LICENSE reads:

Bivariate Cubic Spline approximation library + standalone utility
Version 1.14

Copyright 2002 CSIRO Marine Research
GPO 1538 Hobart
TAS 7001
Australia
Please send comments and bugs to Pavel.Sakov@...272...

There is no warranty whatsoever. Use at your own risk.

These code may be freely redistributed under the condition that the copyright
notices are not removed. You may distribute modified versions of this code
UNDER THE CONDITION THAT THIS CODE AND ANY MODIFICATIONS MADE TO IT IN THE
SAME FILE REMAIN UNDER COPYRIGHT OF CSIRO, BOTH SOURCE AND OBJECT CODE ARE
MADE FREELY AVAILABLE WITHOUT CHARGE, AND CLEAR NOTICE IS GIVEN OF THE
MODIFICATIONS.

If this sounds OK I'll investigate further.

-Jeff

···

--
Jeffrey S. Whitaker Phone : (303)497-6313
NOAA/OAR/CDC R/CDC1 FAX : (303)497-6449
325 Broadway Web : http://www.cdc.noaa.gov/~jsw
Boulder, CO, USA 80305-3328 Office: Skaggs Research Cntr 1D-124

Robert_Kern1 · October 19, 2005, 6:15pm

Jeff Whitaker wrote:

The LICENSE reads:

Bivariate Cubic Spline approximation library + standalone utility
Version 1.14

Copyright 2002 CSIRO Marine Research
GPO 1538 Hobart
TAS 7001
Australia
Please send comments and bugs to Pavel.Sakov@...272...

There is no warranty whatsoever. Use at your own risk.

These code may be freely redistributed under the condition that the
copyright
notices are not removed. You may distribute modified versions of this code
UNDER THE CONDITION THAT THIS CODE AND ANY MODIFICATIONS MADE TO IT IN THE
SAME FILE REMAIN UNDER COPYRIGHT OF CSIRO, BOTH SOURCE AND OBJECT CODE ARE
MADE FREELY AVAILABLE WITHOUT CHARGE, AND CLEAR NOTICE IS GIVEN OF THE
MODIFICATIONS.

If this sounds OK I'll investigate further.

No, the CAPITALIZED part is very much not okay. It means we'd have to
sign over the copyright to our modifications to CSIRO, and that the code
can't be embedded in a commercial or proprietary project.

···

--
Robert Kern
rkern@...376...

"In the fields of hell where the grass grows high
Are the graves of dreams allowed to die."
-- Richard Harter

_Jeff_Whitaker1 · October 19, 2005, 7:35pm

Robert Kern wrote:

Jeff Whitaker wrote:

The LICENSE reads:

Bivariate Cubic Spline approximation library + standalone utility
Version 1.14

Copyright 2002 CSIRO Marine Research
GPO 1538 Hobart
TAS 7001
Australia
Please send comments and bugs to Pavel.Sakov@...272...

There is no warranty whatsoever. Use at your own risk.

These code may be freely redistributed under the condition that the
copyright
notices are not removed. You may distribute modified versions of this code
UNDER THE CONDITION THAT THIS CODE AND ANY MODIFICATIONS MADE TO IT IN THE
SAME FILE REMAIN UNDER COPYRIGHT OF CSIRO, BOTH SOURCE AND OBJECT CODE ARE
MADE FREELY AVAILABLE WITHOUT CHARGE, AND CLEAR NOTICE IS GIVEN OF THE
MODIFICATIONS.

If this sounds OK I'll investigate further.

No, the CAPITALIZED part is very much not okay. It means we'd have to
sign over the copyright to our modifications to CSIRO, and that the code
can't be embedded in a commercial or proprietary project.

Oh well. I'm satisified then that there really isn't anything out there with acceptable license terms. I'm going to post my natgrid-based griddata module on the wiki and call it done (for now).

-Jeff

···

--
Jeffrey S. Whitaker Phone : (303)497-6313
Meteorologist FAX : (303)497-6449
NOAA/OAR/CDC R/CDC1 Email : Jeffrey.S.Whitaker@...259...
325 Broadway Office : Skaggs Research Cntr 1D-124
Boulder, CO, USA 80303-3328 Web : Jeffrey S. Whitaker: NOAA Physical Sciences Laboratory

Alan_G_Isaac1 · October 19, 2005, 11:17pm

My view is that it is always worth asking for a different
license before giving up. Many people choose
licenses thoughtlessly. Some not, of course.

Cheers,
Alan Isaac

PS I tried to find current contact info for the natgrid author
and failed.

···

On Wed, 19 Oct 2005, Jeff Whitaker wrote:

Oh well. I'm satisified then that there really isn't anything out
there with acceptable license terms. I'm going to post my natgrid-based
griddata module on the wiki and call it done (for now).

_Jeff_Whitaker1 · October 20, 2005, 2:44pm

Robert Kern wrote:

Jeff Whitaker wrote:

The LICENSE reads:

Bivariate Cubic Spline approximation library + standalone utility
Version 1.14

Copyright 2002 CSIRO Marine Research
GPO 1538 Hobart
TAS 7001
Australia
Please send comments and bugs to Pavel.Sakov@...272...

There is no warranty whatsoever. Use at your own risk.

These code may be freely redistributed under the condition that the
copyright
notices are not removed. You may distribute modified versions of this code
UNDER THE CONDITION THAT THIS CODE AND ANY MODIFICATIONS MADE TO IT IN THE
SAME FILE REMAIN UNDER COPYRIGHT OF CSIRO, BOTH SOURCE AND OBJECT CODE ARE
MADE FREELY AVAILABLE WITHOUT CHARGE, AND CLEAR NOTICE IS GIVEN OF THE
MODIFICATIONS.

If this sounds OK I'll investigate further.

No, the CAPITALIZED part is very much not okay. It means we'd have to
sign over the copyright to our modifications to CSIRO, and that the code
can't be embedded in a commercial or proprietary project.

Robert: But this refers to modifications made to it "in the same file". The way I read this, if we don't change his source files we can redistribute them any way we want, as long as we leave the CSIRO copyright notices alone.

-Jeff

···

--
Jeffrey S. Whitaker Phone : (303)497-6313
Meteorologist FAX : (303)497-6449
NOAA/OAR/CDC R/CDC1 Email : Jeffrey.S.Whitaker@...259...
325 Broadway Office : Skaggs Research Cntr 1D-124
Boulder, CO, USA 80303-3328 Web : Jeffrey S. Whitaker: NOAA Physical Sciences Laboratory

_Chris_Barker · October 20, 2005, 4:17pm

Jeff Whitaker wrote:

Robert: But this refers to modifications made to it "in the same file". The way I read this, if we don't change his source files we can redistribute them any way we want, as long as we leave the CSIRO copyright notices alone.

I think Robert already answered this one: while we cold do that, we would then be distributing code with MPL that carried extra restrictions, so that MPL users couldn't modify it at will. I agree that this is to be avoided.

Perhaps it's time to start a SciPy-extras collection that includes code under other, weird licenses.

This would be SO much easier of people throwing their code out on the Internet would just use one of the common licensing schemes.

I still think it's worth talking to the author, however. As Robert pointed out, these folks are clearly not all that cluefull about open source licenses. They may have little idea what they really are restricting. As a simple example, someone on the wxPython list has been developing a bunch of nifty higher-level widgets, hoping to get them included in the wxPython lib. However, he had released them all under the GPL, just because he didn't know any better. When someone wrote to him, pointing out that his stuff couldn't be used in any non-GPL projects, it turns out that wasn't his intent. I think he's going to re-release it all under the wxWidgets license (modified LGPL).

However, it looks like this one may be standard CSIRO policy, so the author may have no choice, and changing an institutional policy is MUCH harder!

Another, semi-related, thought: I feel strongly that MPL should focus on being a plotting library, NOT a full blown computational environment. That should be the focus of SciPy. Therefore, code to interpolate unstructured data would be better put into SciPy than MPL. Same licensing issues, of course.

-Chris

···

--
Christopher Barker, Ph.D.
Oceanographer

NOAA/OR&R/HAZMAT (206) 526-6959 voice
7600 Sand Point Way NE (206) 526-6329 fax
Seattle, WA 98115 (206) 526-6317 main reception

Chris.Barker@...259...