Como nota final, a projecção que pretende - Hayford-Gauss Datum Militar de
Lisboa - tem no Manifold system GIS a seguinte correspondencia: Cylindrical
-> Transverse Mercator e como Datum -> International Reference 1924. Vai
verificar que com esta configuração, os parâmetros são iguais ao do PRJ
fornecidos na shape file do cartograma disponibilizado em SHP pelo IGEOE.

Cumprimentos
J.Seixas







>From: "JP RS" <cao_rafeiro@...>
>Reply-To: manifold-gis@...
>To: manifold-gis@...
>Subject: RE: [manifold-gis] Manifold - conversão de coordenadas
>Date: Sun, 07 May 2006 15:01:40 +0000
>
>Algumas respostas:
>
>1) "Shapefiles and PRJ Files
>
>The use of .prj files together with shapefiles to specify projections is a
>recent development that, unfortunately, has come into play without any
>definitive standards being published to precisely specify how the .prj
>should code its contents. Although the use of .prj files works most of the
>time, it is something of a haphazard system. If a shapefile is accompanied
>by a .prj file Manifold will analyze the .prj to try to determine what
>projection and projection parameters are intended for the shapefile.
>
>Manifold recognizes over 490 projection types used in .prj files and so
>will
>be able to extract the projection information in almost all cases, reading
>more different types of .prj than almost all other software packages that
>can read shapefiles. However, because .prj files do not use standardized
>nomenclature for projections it is possible that in some cases it will not
>be possible to read the desired projection even if the shapefile is
>accompanied by a .prj file. manifold.net is always on the lookout for .prj
>files containing previously-unknown standards to add to our "zoo" of
>strange
>examples. If you encounter a shapefile using a .prj that does not import
>into Manifold correctly, please contact tech support for instructions on
>how
>to FTP it to manifold.net for examination."
>http://exchange.manifold.net/manifold/manuals/5_userman/mfd50Import_Drawing__SH\
P_Shapefiles.htm
>----------------------------------------------------------------------
>2) "Shapefiles as most commonly occur do not save projection information.
>Recent extensions to ArcView allow the saving of projected data in
>additional .prj files; however, most shapefiles that are published do not
>use this extension. Shape format is therefore best used to interchange data
>from unprojected drawings using degrees as the unit of measure. When such
>shape files are imported into Manifold they will appear in Latitude /
>Longitude projection without any difficulty.
>
>When importing an unprojected shapefile keep on the lookout for any
>information that tells you what datum was used in that file. Importing an
>unprojected shapefile will by default import the shapefile using Latitude /
>Longitude projection using the WGS 84 centroid. Such imports will be
>acceptable for many GIS purposes; however, for full accuracy one should
>find
>out what centroid was used for the shapefile being imported and use Edit -
>Properties- Current Projection dialog (called by pressing the Current
>Projection button in the Edit - Properties dialog) to specify it for the
>imported drawing.
>
>Serious difficulties can arise when people project drawings and then save
>the resulting projected data as a shapefile. In such cases there is no
>guaranteed clue that the shapefile contains projected data and cannot be
>interpreted as a Latitude / Longitude map. Worse yet, there is not
>information contained within the shapefiles that specifies the projection
>and parameters used. If these are not provided within some readme.txt file
>or other accompanying documentation, the shapefiles lose their geographic
>context."
>http://exchange.manifold.net/manifold/manuals/5_userman/mfd50Import_Drawing__SH\
P_Shapefiles.htm
>---------------------------------------------------------------------
>3) "Import the data and then immediately use Edit - Projection - Current
>Projection to tell Manifold the correct projection that is inteded. After
>that, you don't ever touch the Current Projection dialog again for that
>component. Thereafter, you re-project, if desired, using Edit - Projection.
>But, none of that will work if you do not correctly assign the current
>projection immediately after import - *anything* you do after that will be
>wrong and utterly worthless if that first current projection step is not
>accurately done.
>
>Assuming that you got all the files available, it may be comforting to know
>that all the above is not Manifold's fault: it is the fault of the person
>who is providing projected information within shapefiles. They are the ones
>who have made your life miserable by laying this trap for you. Let's hope
>they are a decent person who has lapsed into evil due to funding
>constraints
>and that even though they know what they are doing is wrong they feel it is
>better they get these files out to the public no matter how gruesome the
>shape (ha, ha... a pun :-) they may be in. If they had consideration for
>the
>public (or adequate resources if that is the problem) they'd publish the
>data as simple lat/lon in shapefiles (if they felt they had to use
>shapefiles) or they'd use a sensible format such as SDTS (if they felt
>compelled to publish it in projected form)."
>http://forum.manifold.net/Site/Thread.aspx?id=20708&ti=632818348244670000
>-------------------------------------------------------------------------------
>4) "I do not know of any third-party tool to create a prj file except
>perhaps
>FME?
>As you have rightly observed, the shp format does not include any
>coordinate system information.
>The prj file came as a later addition when ESRI discovered that people
>were using the shp format to transfer geographic information.
>
>The only way I know to make a prj file is a bit complicated. You need to
>use ArcCatalog and define the shape property of the file.
>It's of course necessary that you 1/ know which system is used, and 2/
>that system exists in the pre-defined list. (you can probably add your own
>definitions but that's another cup altogether).
>Last time I checked, though I found that MapInfo does not use prj files
>even if it's there.
>
>I would be interested to know from you people on the list, what GISes you
>know of that uses ESRI prj files?
>Not counting of course any ESRI or affiliated software.
>
>Hälsning / Best regards Mats.E"
>http://www.directionsmag.com/pipermail/mapinfo-l/2005-December/000529.html
>-----------------------------------------------------------------------
>5) I am not able to load the file ‘parcels.shp’ at the following site into
>Google Earth…
>
>http://www.ci.fitchburg.ma.us/ftp/shape_files/
>
>I recently bought the Pro version and import and print modules specifically
>to have the city of Fitchburg’s parcels loaded in Google Earth.
>
>I have no way of supplying the ‘.prj’ file that GE asks for when I try to
>import ‘parcels.shp’. The zip file at the above-mentioned site only has
>three files, 'parcels.shp', 'parcels.shx', and 'parcels.dbf'. I use these
>all the time in ArcExplorer.
>
>Is there a guru out there that has some sort of workaround?
>
>I noticed on Sketchup's forum that GE and Sup are able to talk to each
>other
>now, so I'll be exloring this as an option (albeit, a clumsy one)...
>
>Thanks for any info / help that can be provided,
>
>Darin
>http://bbs.keyhole.com/ubb/showflat.php/Cat/0/Number/56982/Main/55652
>------------------------------------------------------------------------
>
>Resumindo, o seu problema não está no Manifold, mas sim, no facto de o
>formato PRJ da ArcGIS não ser standard, tal como o formato PRJ da MapInfo
>não é standard e por aí fora. Ou seja, quando se tenta importar com PRJ
>pode
>dar dados erróneos. O mesmo acontece quando se tenta importar ficheiros
>oriundos no ArcGIS para o MapInfo usando o PRJ de coordenadas do ArcGIS e
>etc. Fazendo uma pequena pesquisa nos diversos foruns de GIS encontrei
>várias mensagens de erros de importação de ficheiros SHP usando as
>referencias do PRJ, até mesmo no FME, o software "Rei das conversões" de
>ficheiros entre ficheidos de software GIS.
>
>Uma das soluções, é exportar no ArcGIS para SHP com a projecção Lat/Long e
>o
>Datum em WGS84 para depois a importar no Manifold sem problemas (ver em 2)
>
>Outra solução, é fazer com se explica em 3. Mas é fazer tal qual é
>explicado
>em 3.
>
>Relativamente a criar um XML para funcionar no Manifold com a projecção
>pretendida - Hayford-Gauss Datum Militar de Lisboa -, sugiro a não se guiar
>pela projecção apresentada pela ArcGIS (e digo-lhe que também é diferente
>da
>forma como a MapInfo constroi a sua estrutura de coordenadas), mas sim, a
>criar um XML com essa projecção da forma como o Manifold reconhece (ver no
>manual do programa como se faz) e usar os parâmetros paresentados pelo
>IGeoE.
>
>Cumprimentos
>J.Seixas
>
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> >From: "pauloecardoso" <pec@...>
> >Reply-To: manifold-gis@...
> >To: manifold-gis@...
> >Subject: [manifold-gis] Manifold - conversão de coordenadas
> >Date: Sat, 06 May 2006 22:31:39 -0000
> >
> >Eventualmente alguém, cá em Portugal (mas outras conversões também
> >produziriam o mesmo efeito) já terá tentado, com aparente sucesso,
> >converter no Manifold (6.5 Enterprise edition)dados georeferenciados em
> >Hayford-Gauss Datum Militar de Lisboa (IGEOE) para WGS84 (e vice-versa).
> >Se alguém tentou essa operação, provavelmente terá comparado o
> >resultado com dados convertidos no Arcgis ou no site INOVAGIS ou no
> >próprio site do IGEOE ou ainda pelo programa do IPCC. O Manifold produz
> >resultados inaceitáveis.
> >O Manifold, dizem, também é capaz de importar a referência geográfica
> >de um ficheiro prj do Arcgis. A verdade é que também não o faz. Faltam
> >lá parâmetros que estão no prj.
> >Será que sou eu a errar? Quem trabalha com escalas reduzidissimas e
> >aceita erros de 200m escusa de responder.
> >Terá alguém o xml milagroso que fará o Manifold por tudo no lugar?
> >
> >Paulo Cardoso
> >bio3, Lda.
> >
> >
> >
>
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