[Proj] Re: Proj Digest, Vol 52, Issue 17

Jay Hollingsworth jhollingsworth at houston.oilfield.slb.com
Fri Sep 12 16:57:36 EDT 2008

At the risk of opening a floodgate of alternate 
suggestions, the EPSG is the source of the 
projection parameters and they have several 
Guidance notes at 
http://www.epsg.org/guides/index.html, including 
something for a more general audience (Guidance 
Note 1) as well as more-detailed notes on the 
transformation and projection equations and special problems.

I know these aren't proj-specific, but they have 
a lot of content to help decide what to use.


At 11:01 AM 9/11/2008, you wrote:
>Message: 1
>Date: Thu, 11 Sep 2008 11:17:06 -0400
>From: "Gerald I. Evenden" <geraldi.evenden at gmail.com>
>Subject: Re: [Proj] Some need for updated proj-4 manuals
>To: "PROJ.4 and general Projections Discussions"
>         <proj at lists.maptools.org>
>Message-ID: <200809111117.06551.geraldi.evenden at gmail.com>
>Content-Type: text/plain;  charset="iso-8859-1"
>On Thursday 11 September 2008 8:10:32 am support.mn at elisanet.fi wrote:
> > Hello,
> >
> > the proj-4 manuals might need some updating and cleaning?
> > There are basicly two groups whcih need them.
>Between answering all the emails I sometime work on the manual .
>Have you looked at the libproj4 manual.pdf on:
>It is 123 pages but getting a bit old.  The 
>version in my machine is up to 128
>pages plus corrections and I am working on an improved TM section which will
>add 7 or 8 pages.  The sections on cylindricals and pseudocylindricals are
>fairly complete.  Most work is needed on conic.  Miscellaneous is fairly
>complete.  The math for all projections is given so one can see how the
>various options relate to the computations.  Internal library procedures are
>fairly complete.
>The above manual does not cover lproj options (-x etc.) but they are almost
>identical to older documentation of proj.
>I would like some detailed illustrations related to things like local grid
>systems but at the moment I do not have sufficiently detailed coastline file
>to do them.
>My manuals do not do datums.
> > A) Programmers that utilise the library. More or less programming
> > related matters and details. This could be the "Proj-4 Programmer's
> > Manual".
> >
> > B) End users that use the projections. They need information what
> > can be done. What is available and what are the exact parameters
> > and how to use them in each projection and datum available.
> > Exmples are most informative. This might be something like
> > "Proj-4 End User´s Manual". These people are mostly not interrested
> > of the programming details and those matter should be put in the
> > first manual. Then there is also the end application´s "User Manual",
> > which tells more about the application and how to use it.
> > That would be the third manual, written by the proj-4-application
> > makers. Maybe the proj-4 part would be an appendix in this
> > manual?
>I do not need to take my shoes off to count the 
>projections that are difficult
>to use---omerc is a good example of a stinker.  Also, I cannot over emphasize
>the use of the -V option with [l]proj where one can experiment with the
>options and where the output will also tell the user if an option is
>specified and not used by the projection.
> > So the "Proj-4 End User Manual" goes to the end user, if the
> > proj-4 definition is directly visible for the end user... sometimes
> > not, if there is a layer above proj-4.
> >
> > Now the situation is so that there are several proj-4 manuals in
> > pdf format and it is hard to find any specific information especially
> > about "how to use the projections and datums" since the
> > information is here and there. At least one would expect to
> > find all projections and their usage (and datums) in one manual .
> >
> > And of course to keep those 2 manuals up to date to the latest
> > program versions. Manuals might have same versions as
> > programs so that everything would be documented.
> >
> > The end application manuals and documentations keep us so
> > busy that any help with the projections and datums would be
> > highly respected. BTW: Our application can only use those
> > projections that have both forward and inverese projections.
> > So it would be nice if those projections with missing inverese
> > projection would be separated somehow in it´s own group.
> >
> > Etc. etc.
> >
> > Any ideas? Somebody might want to collect and compose
> > those two proj-4 manuals using the pdf originals that are
> > somewhere? Anyway that is what we would very much need.
> >
> > We might hide all the projection and datum complexity in some
> > applications (ready made maps), but sometimes they are visible.
>To be sure. there are different interest and capability levels that manuals
>address.  However, my only intererst is to provide documentation that is as
>complete as possible but also, in the interests of brevity, assumes that the
>reader has sufficient background and related skill to understand that
>material and how to properly apply it.  It is not an elementary how-to
>Please, please, please.  Anyone finding errors in the previously reference
>manual please notify this group.  Thank-you.
>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

Jay Hollingsworth

Seabed Portfolio Manager and
Principal Data Architect
Schlumberger Information Solutions
phone: 713 513 8854 fax: 713 513 2093

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