No discussion of "free" software is complete without some mention of the various licenses. Assorted links on this page pointing to where source code for things included in the downloadable bundles can be obtained. I think I'm covered.
cartogram.pl
The program cartogram.pl,
and any executable binary files based on it,
are licensed under
the GNU General Public License version 3.
Fundamentally:
- What you do with the software in the privacy of your own computer is your own business. Acknowledgement if you use cartograms generated by the software is nice, but not required.
- If you choose to redistribute the software, or a modified version of it, you must do so under the same terms. That is, provide the source code (including your enhancements, if any), maintain the copyright markings (and add your own as necessary), use the same license or its successors. No charging money other than nominal fees to cover the actual costs of producing physical media if such are used.
cart
So far as I can tell,
the cart software is unrestricted in any fashion.
The copy I downloaded from the University of Michigan
does not include either copyright or licensing terms.
However,
see the libfftw note.
It appears (at least to me, although IANAL) that the use of libfftw imposes an obligation to redistribute.
cart source code is available
here,
and is also included in the bundles.
libfftw
Libfftw,
on which cart depends,
is distributed under the GNU General Public License version 2.
It is specifically not distributed under the Lesser GNU License
(sometimes called the library license).
As such,
it has (in my opinion) the "contagion" problem –
code that makes use of the library also falls under the GNU license.
Versions of libfftw
without the contagion problem
are available through the MIT Technology Licensing Office.
Libfftw source code is available
here.
cs2cs
cs2cs is distributed under MIT's open-source license.
The MIT open-source license –
not to be confused with licenses obtained through MIT's licensing office
as previously mentioned –
is as close to being public domain as is possible
while still retaining a copyright notice.
Information on the proj.4 project,
including source code,
is available
here.
Map files
Maps that are automatically generated
make use of shapefiles from the US Census Bureau.
There are no restrictions on use
except that the Bureau should be acknowledged.
I'd include some sort of pointer into the Census Bureau's web site,
but they seem to rearrange and rename things regularly,
creating lots of dead links.
POV-Ray and MegaPOV
Two different forms of the POV-Ray ray-tracing program are included
in the downloadable bundles.
POV-Ray version 3.7
(Mac and linux bundles)
is covered by the GNU Affero General Public License.
MegaPOV version 1.2.1
(Windows bundle)
is a defunct project based on POV-Ray version 3.6.1
and is covered by the the same Affero license.
Technically,
a full installation of the POV-Ray software source code
seems to be required in order to use MegaPOV.
The necessary intallers for POV-Ray can be found
here.
MegaPOV source downloads can be found
here.
ffmpeg
The ffmpeg core is covered under the
GNU Lesser General Public License (LGPL) version 2.1 or later.
Some optional parts of the program are covered under the
GNU General Public License (GPL) version 2 or later.
If those parts are included,
the GPL applies to all of ffmpeg
(see the contagion problem mentioned above).
ffmpeg comes with an added licensing wrinkle: patents. According to their web page on legal considerations, it is possible that ffmpeg uses patented algorithms. It's a complicated subject.
Next: Command-Line Options
Last updated Feb 23, 2018