Sebastiaan Couwenberg | 2 Feb 07:09 2016
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PROJ.4 4.9.2 and transformation of points outside datum shift grid

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Debian Bug #813066 [0] revealed a bug in the test handling of the
conversion between RD/NAP and ETRS89 when PROJ.4 4.9.2 is used.

Previous versions of PROJ.4 were unable to transform points outside the
available datum shift grid, as can be seen in the output of the test
script [1] in the file testrdtrans2008-4.9.1 [2].

With version 4.9.2 some points can now be calculated as seen in the
file testrdtrans2008-4.9.2 [3], but for tests 07 to 10 (whose points
"are outside the region where interpolation between either the NLGEO2004
geoid or the RD correction grid points is possible") in the direction
from RD/NAP to ETRS89 the results are entirely incorrect, whereas the
results for those same tests in opposite direction are mostly correct
except test 10 (edge_rd).

The documentation accompanying the rdtrans2008.gsb NTv2-grid and
naptrans2008.gtx VDatum-grid [4] mentions that the points for test 07 to
10 are outside the correction grid and that their "RD coordinates can be
computed, but the output should be handled with care".

With earlier versions there was no usable output, 4.9.2 reports
incorrect values (for some tests).

It looks like the fix for #292 [5][6] is the cause of this change. I'm
not sure whether this change is a bug or a feature.

In de debug logging for 4.9.2 we can see that for tests 07 to 10
pj_apply_vgridshift is no longer called, instead pj_apply_gridshift is
(Continue reading)

Gabor TIMAR | 23 Jan 19:46 2016
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Some details on German Army Grid (Re: MGRS invented by Germany?)

Dear Colleagues,

the cited German paper was interesting indeed, thanks to Charles for the 
reference. I requested the full text from the author via the 
ResearchGate (first author is registered there). Perhaps I'm allowed to 
share some details of the DHG system (and sorry, nothing about the 
similarities to MGRS here):

According to my best knowledge, the German DHG and the Russian 
Gauss-Krueger belts (the latter one MIGHT be a result of the pre-war 
cooperation between these empires) were the first transverse Mercator 
zone systems with 6 degrees zones. In the Russian system (used later 
also by the Warsaw Pact military), the zones were indicated by a 
'leading digit' in the Easting coords (e.g. in the zone '34', between 
18-24d longitude, the False Easting number was 4,500,000 instead of the 
standard 500,000 of the modern UTM - this digit '4' indicated the second 
digit of the zone number. And yes, the Russian maps of the Himalayas has 
False Easting of 14,500,000 ) In some German war maps, this leading 
digit was not used, while in the restored Hungarian war basepoint list, 
it was used. The earlier introduced German civilian grid used the 
3-degree wide zones, the same system that is used nowadays in Germany.

During the WWII, the Germans made a tremendous work, integrating many 
European networks and maps to their DHG system. A key person behind this 
operation was an Austrian expert, dr. Karl Ledersteger (Austria was 
annexed by Germany in 1938), and after the war, he published some 
interesting details about this in Vienna. If someone is interested 
(Cliff maybe?), I can send one in PDF, of course it is in German language.

The hardest part of this integration was to make a more or less unified 
(Continue reading)

Charles Karney | 22 Jan 16:31 2016
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MGRS invented by Germany?

This paper

   M. F. Buchroithner and R. Pfahlbusch,
   "Geodetic grids in authoritative maps -- new
   findings about the origin of the UTM grid" (2016)
   http://dx.doi.org/10.1080/15230406.2015.1128851

has some interesting background on the origins of UTM and MGRS.

In particular, the division of non-polar regions into 60 zones, the
numbering of the zones, and the specific conventions adopted for MGRS
all seem to have been borrowed by the US Army Map Service from the
German military work in 1943-1944.

Figures 3 and 8 show 2 wartime orthophotos of 1km squares in Estonia and
Lithuania with designations (UTMREF), 35VLF6992 and 34UEG0578, which
coincide with the present-day MGRS designations for these areas
(respectively 59.451N 24.698E and 55.752N 21.088E).

(The correspondence isn't exact because of differences in the datum and
in the choice of the scale on the central meridian.)

--

-- 
Charles Karney <charles.karney <at> sri.com>
SRI International, Princeton, NJ 08543-5300

Tel: +1 609 734 2312
Fax: +1 609 734 2662
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(Continue reading)

Stéphane Henriod | 23 Nov 12:40 2015
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Having a CRS added in the common libraries

Dear all


I am new to both lists (proj and metacrs) so my apologies for cross-posting, I am not quite sure where my question belongs.

I am working in the beautiful country of Kyrgyzstan, which happens to have developed a new national geodetic framework. One of the outputs is a coordinate system (Kyrg06), divided in 5 zones.

As far as I know, this coordinate system is not yet available in any common library / software and is neither in the EPSG list. 

Is there any standard process to get a sort of international recognition? This system has been approved by the government and thus has a legal validity in this country. But it will always be difficult to convince people to use it as long as it's not readily available in the common software (and thus in the underlying libraries). As a result, many GIS users end up working with UTM or other not-so-optimal.

Thanks a lot in advance for your hints and advice on this matter

Cheers

Stéphane


--

"Le mot progrès n'aura aucun sens tant qu'il y aura des enfants malheureux" -- Albert Einstein

"Si les contacts avec les étrangers lui étaient permis, [le citoyen ordinaire] découvrirait que ce sont des créatures semblables à lui-même et que la plus grande partie de ce qu'on lui a raconté d'eux est fausse. Le monde fermé, scellé, dans lequel il vit, serait brisé, et la crainte, la haine, la certitude de son bon droit, desquelles dépend sa morale, pourraient disparaître" -- George Orwell ("1984")

“When you travel, remember that a foreign country is not designed to make you comfortable. It is designed to make its own people comfortable." -- Clifton Fadiman

Photos de voyages, photos de montagne: http://www.henriod.info  

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Martin Vermeer | 17 Nov 21:37 2015
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Position open at Aalto University: professorship in geoinformatics


http://www.aalto.fi/en/about/careers/jobs/view/647/

Deadline January 4, 2016

Please share with potentially interested people

Martin
Thomas Knudsen | 12 Nov 16:40 2015
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etmerc original author Knud Poder turns 90.

After my recent post about Knud Poder, I was contacted by geodesy
professor Martin Vermeer, of Aalto University, Finland, who used to
collaborate with Knud Poder. He asked med to post this follow up to
the proj mailing list. So I hereby hand over the microphone to Martin:

Yes, I recently corresponded with Poder and yes, he actively follows
the field.

Back in 1988-1992 when I was in Denmark at the National Survey &
Cadastre -- and before that, the Geodætisk Institut in Ordrup, in a
beautiful country estate --, we saw a lot of each other. He was always
ready to help and explain about the GIER computers and the BOSS
operating system. I remember entering his room, negotiating my way
through the tangible pipe tobacco smoke filling the room, to find him
sitting at his glass teletype terminal, writing code. A Unix nerd, he
too. A thick aluminum ash tray by his side, which had seen all the
mountain tops of Greenland :-)

Dr Poder was made an honorary doctor at Copenhagen University,
proposed IIRC by Carl Christian Tscherning, who died a year ago. That
was early 1990s.

Knud's life hasn't always been easy: a few years later his son Niels
suffered an internal organ failure and was left brain damaged as a
result. That was tough.

/ Martin Vermeer
former employee and colleague at what is now the Danish Geodata Agency
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Dirk Peinelt | 2 Nov 13:09 2015
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EPSG-Code Definition for MGI

Hello,
the EPSG-code definitions for 31256 - 31258 (MGI = Austrian date) on the master are different with spatialreference.org.:

https://github.com/OSGeo/proj.4/blob/master/nad/epsg/
http://spatialreference.org/ref/epsg/31256/proj4/
http://spatialreference.org/ref/epsg/31257/proj4/
http://spatialreference.org/ref/epsg/31258/proj4/

Could be here a bug in proj.4 EPSG database?

Thank you in advance!
Dirk
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Davide Cesari | 29 Oct 09:17 2015
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etmerc original author Knud Poder turns 90.

As described in a recent thread, for the next release, proj.4 will switch the default transverse mercator implementation from tmerc to etmerc.


This is probably a good occasion to reiterate the history of the code for the etmerc implementation - especially since the original author, Knud Poder, turned 90 on October 19th. Having his transverse mercator implementation becoming the proj.4 default is a strikingly proper way of celebrating Poder, among colleagues and collaborators rightfully considered “the Nestor of computational geodesy”.


Poder wrote the first version of what is now known as etmerc, around 1961. It was written in Algol-60 and ran on the GIER computer, built for the Danish Geodetic Institute (see [1] for details).


The code was based on theoretical foundations published a decade earlier, by König & Weise ([2], building on prior work by Krüger, 1912 [3]).


Poder’s work was characterized by great care with respect to numerical precision and accuracy (e.g. by using Clenshaw summation for recurrence series, and Horner’s scheme for polynomial evaluation).


Also, Poder was noted for his ingeniously implemented “dual autochecking method” (not used in the proj.4 version), where the same code was used for forward and inverse projections and was run both ways and compared, to protect against both coding- and hardware errors. The latter was very important at a time where the mean time between failure for computer systems was much shorter than today.


During the 1970s Poder’s student, Karsten Engsager (the “E” in etmerc, “Engsager Extended Transverse Mercator”) took over maintenance and eventually extended König and Weise’s numerical series by another term, bringing the accuracy up to today’s standard.


In 2008, through the efforts of a.o. Gerald Evenden, Frank Warmerdam and Karsten Engsager, etmerc was introduced in proj.4, while in 2013 Charles Karney provided 3 corrections - stressing the value and importance of open source code sharing.


Poder retired 20 years ago, but has been taking active interest in the maintenance and development of his code ever since. Switching proj.4 to use a transverse mercator implementation based on his work is probably the best conceivable way of celebrating the 90th birthday of a great Nestor of computational geodesy.


In celebration of Knud Poder!


/Thomas Knudsen, Danish Geodata Agency




[1] Thomas Knudsen, Simon L. Kokkendorff, Karsten E. Engsager (2012): A Vivid Relic Under Rapid Transformation, OSGeo Journal vol. 10, pp. 55-57, URL https://journal.osgeo.org/index.php/journal/article/download/200/167


[2] R. König and K. H. Weise (1951): Mathematische Grundlagen der Höheren Geodäsie und Kartographie, Erster Band. Springer, Berlin/Göttingen/Heidelberg, 1951. K


[3] L. Krüger (1912): Konforme Abbildung des Erdellipsoids in der Ebene. Neue Folge 52. Royal Prussian Geodetic Institute, Potsdam. URL http://bib.gfz-potsdam.de/pub/digi/krueger2.pdf


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Charles Karney | 28 Oct 15:13 2015
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Gan'shin, Geometry of the earth ellipsoid, and other translations

I've scanned and uploaded

     N. V. Gan'shin, Geometry of the earth ellipsoid (ACIC, 1969)

This and some other translations I've previously announced are available
as follows:

     Helmert (1880), https://dx.doi.org/10.5281/zenodo.32050
     Helmert (1884), https://dx.doi.org/10.5281/zenodo.32051
     Bagratuni (1967), https://dx.doi.org/10.5281/zenodo.32371
     Gan'shin (1969), https://dx.doi.org/10.5281/zenodo.32854

   --Charles
--

-- 
Charles Karney <charles.karney <at> sri.com>
SRI International, Princeton, NJ 08543-5300

Tel: +1 609 734 2312
Fax: +1 609 734 2662
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Thomas Knudsen | 28 Oct 14:56 2015
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etmerc original author Knud Poder turns 90.

As described in a recent thread, for the next release, proj.4 will switch the default transverse mercator implementation from tmerc to etmerc.


This is probably a good occasion to reiterate the history of the code for the etmerc implementation - especially since the original author, Knud Poder, turned 90 on October 19th. Having his transverse mercator implementation becoming the proj.4 default is a strikingly proper way of celebrating Poder, among colleagues and collaborators rightfully considered “the Nestor of computational geodesy”.


Poder wrote the first version of what is now known as etmerc, around 1961. It was written in Algol-60 and ran on the GIER computer, built for the Danish Geodetic Institute (see [1] for details).


The code was based on theoretical foundations published a decade earlier, by König & Weise ([2], building on prior work by Krüger, 1912 [3]).


Poder’s work was characterized by great care with respect to numerical precision and accuracy (e.g. by using Clenshaw summation for recurrence series, and Horner’s scheme for polynomial evaluation).


Also, Poder was noted for his ingeniously implemented “dual autochecking method” (not used in the proj.4 version), where the same code was used for forward and inverse projections and was run both ways and compared, to protect against both coding- and hardware errors. The latter was very important at a time where the mean time between failure for computer systems was much shorter than today.


During the 1970s Poder’s student, Karsten Engsager (the “E” in etmerc, “Engsager Extended Transverse Mercator”) took over maintenance and eventually extended König and Weise’s numerical series by another term, bringing the accuracy up to today’s standard.


In 2008, through the efforts of a.o. Gerald Evenden, Frank Warmerdam and Karsten Engsager, etmerc was introduced in proj.4, while in 2013 Charles Karney provided 3 corrections - stressing the value and importance of open source code sharing.


Poder retired 20 years ago, but has been taking active interest in the maintenance and development of his code ever since. Switching proj.4 to use a transverse mercator implementation based on his work is probably the best conceivable way of celebrating the 90th birthday of a great Nestor of computational geodesy.


In celebration of Knud Poder!


/Thomas Knudsen, Danish Geodata Agency




[1] Thomas Knudsen, Simon L. Kokkendorff, Karsten E. Engsager (2012): A Vivid Relic Under Rapid Transformation, OSGeo Journal vol. 10, pp. 55-57, URL https://journal.osgeo.org/index.php/journal/article/download/200/167


[2] R. König and K. H. Weise (1951): Mathematische Grundlagen der Höheren Geodäsie und Kartographie, Erster Band. Springer, Berlin/Göttingen/Heidelberg, 1951. K


[3] L. Krüger (1912): Konforme Abbildung des Erdellipsoids in der Ebene. Neue Folge 52. Royal Prussian Geodetic Institute, Potsdam. URL http://bib.gfz-potsdam.de/pub/digi/krueger2.pdf


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till | 17 Oct 01:02 2015
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Fw: new message

Hello!

 

New message, please read http://soundcloudblast.com/seems.php

 

till <at> free.fr

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