[Proj] libproj4: next author release
Gerald I. Evenden
geraldi.evenden at gmail.com
Thu Nov 6 13:17:46 EST 2008
The most difficult aspect of iterative inverse projection solutions is finding
adequate initial coordinate guesses, especially with elliptically shaped
outlines such as Hammer and Aitoff. The ones I currently have work but could
be improved but one needs to draw the line somewhere.
I have persisted in retaining the GSL as the method of choice as it is much
superior to the raw Newton-Raphson method with each iteration generally
refining the position by 10^-3 and more while the former plugs along at
10^-2. In addition, the GSL works nicely (almost as well as basic
Newton-Raphson) when analytic derivatives are not known.
If the GPL license required by the the GSL is too stringent then the
distribution is easily compiled without the GSL tools---and no new inverses.
This condition has been in effect for some time as it already affects other
I do not distribute the GSL library because I do not have a copy of the
sources to distribute. My library is downloaded by RPM from Ubuntu sources.
libproj4 update should be on my website this weekend.
The next release will be split into two tars: libproj4 itself and program
lproj will be moved to a separate container. The reason for this is that I
am going to upgrade lproj to include better runline option inclusion
operations with the help of 'gengetopt' and use of "runline" input. The
later is born out of my poor typing skills and having to retype the whole
line rather than simply <bs>/correct.
In addition, I will restore the input of flat-file projection definition data
base capability once available with proj but without reference to include
files---+no_def remains an ignored option. Thus <id> +options <> will be
back in effect. I will probably modify <id> to <id:comments> where the ':'
will delimit the identifier key. Usage will be something
like --lookup=id at filename (or something similar).
Options like --roundtrip for cycling though forward->inverse will be included
and possibly escaping input to allow reinitializing a projection from the
For cases where lproj is simply used as pipe plumbing a stripped down version
of lproj will be included and will probably simply be called 'proj'.
The whole religious complexion of the modern world is due
to the absence from Jerusalem of a lunatic asylum.
-- Havelock Ellis (1859-1939) British psychologist
More information about the Proj