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On 20:59, Gerald I. Evenden wrote:
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cite="mid:%3C201002131316.00892.geraldi.evenden@gmail.com%3E"
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<pre wrap="">On Saturday 13 February 2010 12:28:57 pm Luigi Ponti wrote:
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<pre wrap="">Hello,
I use PROJ.4 via GRASS GIS, and I would like to know if anyone is aware
of a standard projection for mapping the whole Mediterranean basin. I
need to do raster-based statistics on the maps, so I guess what I am
looking for is an equal area projection.
What I have found on the Web is a GIS built by the Joint Research Center
(JRC <a class="moz-txt-link-freetext" href="http://www.jrc.ec.europa.eu/">http://www.jrc.ec.europa.eu/</a>) that used Lambert Azimuthal Equal
Area (LAEA) for the Mediterranean:
<a class="moz-txt-link-freetext" href="http://re.jrc.ec.europa.eu/pvgis/info/faq.htm#projection">http://re.jrc.ec.europa.eu/pvgis/info/faq.htm#projection</a>
However, it adopted the same projection center for both Europe and the
Mediterranean (0 °E and 48 °N). Is this correct?
There is also a workshop report
<a class="moz-txt-link-freetext" href="http://www.ec-gis.org/sdi/publist/pdfs/annoni-etal2003eur.pdf">http://www.ec-gis.org/sdi/publist/pdfs/annoni-etal2003eur.pdf</a>
that recommended LAEA with projection center 9 °E and 53 °N to be used
for statistical mapping in the European Union.
Based on this background it seems like LAEA would be fine. However, I am
unsure if there is a standard projection center and datum.
Thank you for any hints. Kind regards,
Luigi
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Personal opinion: because you seem to have your own project needs that has not
shown a need to match any existing projection I would, because of the general
E-W shape of your region, select Albers Equal Area conic. With reasonably
selected parallels is should give you less distortion at the extremities than
the azimuthal projection.
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<br>
Thank you -- this sounds like a very good suggestion.<br>
<br>
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cite="mid:%3C201002131316.00892.geraldi.evenden@gmail.com%3E"
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A little parameter tuning needs to be done.
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<br>
Really have no clue on how to go about this, but will give it a try.
From what you say, I understand that it would basically be a matter of
finding the right standard parallels: is there a rule of thumb for this?<br>
<br>
Thanks again,<br>
<br>
Luigi<br>
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cite="mid:%3C201002131316.00892.geraldi.evenden@gmail.com%3E"
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I would not be prejudiced by projections where the needs to cover the entire
continent are are the primary consideration.
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