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AI-GEOSTATS: Coordinate conversion near the poles

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  • Ruben Roa Ureta
    Hi list members: I am now embarked in a project of fish stock assessment in the Falklands using both hydroacoustics and fish density data from trawling, and of
    Message 1 of 5 , Feb 13, 2004
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      Hi list members:
      I am now embarked in a project of fish stock assessment in the Falklands
      using both hydroacoustics and fish density data from trawling, and of
      course i want to use geostatistics for data analysis. I read in ai-geostat
      archives a discussion not long ago about coordinate transformation before
      statistical modelling to ensure proper distances. UTM coordinates were
      recommended (the header was GeoR and memmory). The Falklands are quite
      near the south pole so it seems to me at this location coordinate
      conversion is a matter of relevance if i want to have a proper spatial
      representation of the shape of the fish stock down there at the bottom of
      the sea. The final purpose in our case is to integrate over the two
      spatial dimensions of the fish density variable to arrive at a value of
      total biomass. I would appreciate to have a confirmation that the UTM
      coordinate system will account for the true shape of the Earth in my case
      and thus i could proceed to geostatistical modelling after transforming
      from latitude-longitude data to UTM. Thanks.
      Ruben

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    • Jim Bash
      The UTM grid system only extends to 80 degrees south (and 84 north). There is another system for polar areas, the Universal Polar Stereographic Grid System
      Message 2 of 5 , Feb 13, 2004
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        The UTM grid system only extends to 80 degrees south (and 84 north). There
        is another system for polar areas, the Universal Polar Stereographic Grid
        System (UPS). I've never had occassion to look at UPS so I can't say what
        projection is used but it, like the UTM system, is designed to have a
        certain accuracy within a zone. For UTM you can calculate distances and
        directions between any two points in a single zone to an accuracy of one
        meter in 2500 meters (people thing of UTM as being '1 meter resolution or
        accuracy'). I would assume UPS is similar.

        Good Luck!

        jim bash
        jbash@...

        On Fri, 13 Feb 2004, Ruben Roa Ureta wrote:

        > Hi list members:
        > I am now embarked in a project of fish stock assessment in the Falklands
        > using both hydroacoustics and fish density data from trawling, and of
        > course i want to use geostatistics for data analysis. I read in ai-geostat
        > archives a discussion not long ago about coordinate transformation before
        > statistical modelling to ensure proper distances. UTM coordinates were
        > recommended (the header was GeoR and memmory). The Falklands are quite
        > near the south pole so it seems to me at this location coordinate
        > conversion is a matter of relevance if i want to have a proper spatial
        > representation of the shape of the fish stock down there at the bottom of
        > the sea. The final purpose in our case is to integrate over the two
        > spatial dimensions of the fish density variable to arrive at a value of
        > total biomass. I would appreciate to have a confirmation that the UTM
        > coordinate system will account for the true shape of the Earth in my case
        > and thus i could proceed to geostatistical modelling after transforming
        > from latitude-longitude data to UTM. Thanks.
        > Ruben
        >
        > --
        > * To post a message to the list, send it to ai-geostats@...
        > * As a general service to the users, please remember to post a summary of any useful responses to your questions.
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        >

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      • Federico Pardo
        Ruben: Near the poles, some people use the Gauss-Kruger projection method. It will create 2 new Poles at the Earth Equator and you need to choose what Meridian
        Message 3 of 5 , Feb 13, 2004
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          Ruben:

          Near the poles, some people use the Gauss-Kruger projection method.

          It will create 2 new Poles at the Earth Equator and you need to choose what
          Meridian will become the new "Equator".

          Then if you choose Meridian over the Malvinas, they will appear as being at
          the Equator.

          Good luck!

          More information at:

          http://www.google.com/search?hl=en&ie=UTF-8&q=gauss-Kruger+projection&spell=1

          Regards,

          Federico

          At 2/13/2004 Friday 10:32 AM, Ruben Roa Ureta wrote:
          >Hi list members:
          >I am now embarked in a project of fish stock assessment in the Falklands
          >using both hydroacoustics and fish density data from trawling, and of
          >course i want to use geostatistics for data analysis. I read in ai-geostat
          >archives a discussion not long ago about coordinate transformation before
          >statistical modelling to ensure proper distances. UTM coordinates were
          >recommended (the header was GeoR and memmory). The Falklands are quite
          >near the south pole so it seems to me at this location coordinate
          >conversion is a matter of relevance if i want to have a proper spatial
          >representation of the shape of the fish stock down there at the bottom of
          >the sea. The final purpose in our case is to integrate over the two
          >spatial dimensions of the fish density variable to arrive at a value of
          >total biomass. I would appreciate to have a confirmation that the UTM
          >coordinate system will account for the true shape of the Earth in my case
          >and thus i could proceed to geostatistical modelling after transforming
          >from latitude-longitude data to UTM. Thanks.
          >Ruben
          >
          >--
          >* To post a message to the list, send it to ai-geostats@...
          >* As a general service to the users, please remember to post a summary of
          >any useful responses to your questions.
          >* To unsubscribe, send an email to majordomo@... with no subject and
          >"unsubscribe ai-geostats" followed by "end" on the next line in the
          >message body. DO NOT SEND Subscribe/Unsubscribe requests to the list
          >* Support to the list is provided at http://www.ai-geostats.org


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        • Roger Bivand
          On Fri, 13 Feb 2004, Jim Bash wrote: Hold on. hold on! Look, Bergen, Norway is 60N, the Falklands, even with South Georgia, are not even 60S. I protest that
          Message 4 of 5 , Feb 14, 2004
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            On Fri, 13 Feb 2004, Jim Bash wrote:

            Hold on. hold on! Look, Bergen, Norway is 60N, the Falklands, even with
            South Georgia, are not even 60S. I protest that this isn't that near the
            poles, even the Arctic and Antarctic circles are at 66.6...N, and that's
            well within the 80N/S of UTM. The question was whether to transform from
            latlong to anything projected in order to do geostats, and the answer is
            yes, unless your geostats software itself calculates great circle
            distances from latlong coordinates (the fields package in R does, for
            example). So the answer is yes, use a projection of choice, UTM being a
            possibility (depending on the W-E extent of your data), or use software
            that respects that your data are latlong.

            Roger

            (writing from just North of 60N!!)

            >
            > The UTM grid system only extends to 80 degrees south (and 84 north). There
            > is another system for polar areas, the Universal Polar Stereographic Grid
            > System (UPS). I've never had occassion to look at UPS so I can't say what
            > projection is used but it, like the UTM system, is designed to have a
            > certain accuracy within a zone. For UTM you can calculate distances and
            > directions between any two points in a single zone to an accuracy of one
            > meter in 2500 meters (people thing of UTM as being '1 meter resolution or
            > accuracy'). I would assume UPS is similar.
            >
            > Good Luck!
            >
            > jim bash
            > jbash@...
            >
            > On Fri, 13 Feb 2004, Ruben Roa Ureta wrote:
            >
            > > Hi list members:
            > > I am now embarked in a project of fish stock assessment in the Falklands
            > > using both hydroacoustics and fish density data from trawling, and of
            > > course i want to use geostatistics for data analysis. I read in ai-geostat
            > > archives a discussion not long ago about coordinate transformation before
            > > statistical modelling to ensure proper distances. UTM coordinates were
            > > recommended (the header was GeoR and memmory). The Falklands are quite
            > > near the south pole so it seems to me at this location coordinate
            > > conversion is a matter of relevance if i want to have a proper spatial
            > > representation of the shape of the fish stock down there at the bottom of
            > > the sea. The final purpose in our case is to integrate over the two
            > > spatial dimensions of the fish density variable to arrive at a value of
            > > total biomass. I would appreciate to have a confirmation that the UTM
            > > coordinate system will account for the true shape of the Earth in my case
            > > and thus i could proceed to geostatistical modelling after transforming
            > > from latitude-longitude data to UTM. Thanks.
            > > Ruben
            > >
            > > --
            > > * To post a message to the list, send it to ai-geostats@...
            > > * As a general service to the users, please remember to post a summary of any useful responses to your questions.
            > > * To unsubscribe, send an email to majordomo@... with no subject and "unsubscribe ai-geostats" followed by "end" on the next line in the message body. DO NOT SEND Subscribe/Unsubscribe requests to the list
            > > * Support to the list is provided at http://www.ai-geostats.org
            > >
            >
            > --
            > * To post a message to the list, send it to ai-geostats@...
            > * As a general service to the users, please remember to post a summary of any useful responses to your questions.
            > * To unsubscribe, send an email to majordomo@... with no subject and "unsubscribe ai-geostats" followed by "end" on the next line in the message body. DO NOT SEND Subscribe/Unsubscribe requests to the list
            > * Support to the list is provided at http://www.ai-geostats.org
            >

            --
            Roger Bivand
            Econonic Geography Section, Department of Economics, Norwegian School of
            Economics and Business Administration, Breiviksveien 40, N-5045 Bergen,
            Norway, voice: +47-55959355, fax: +47-55959393; Roger.Bivand@...



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          • Jim Bash
            Sorry, I didn t notice the reference to the Faulklands, just the question about near the south pole . 60S isn t that near and UTM would be fine if the study
            Message 5 of 5 , Feb 14, 2004
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              Sorry, I didn't notice the reference to the Faulklands, just the question
              about "near the south pole". 60S isn't that 'near' and UTM would be fine
              if the study stays in one zone.

              On Sat, 14 Feb 2004, Roger Bivand wrote:
              > Hold on. hold on! Look, Bergen, Norway is 60N, the Falklands, even with
              > South Georgia, are not even 60S. I protest that this isn't that near the
              > poles, even the Arctic and Antarctic circles are at 66.6...N, and that's
              > well within the 80N/S of UTM. The question was whether to transform from
              > latlong to anything projected in order to do geostats, and the answer is
              > yes, unless your geostats software itself calculates great circle
              > distances from latlong coordinates (the fields package in R does, for
              > example). So the answer is yes, use a projection of choice, UTM being a
              > possibility (depending on the W-E extent of your data), or use software
              > that respects that your data are latlong.

              --
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              * As a general service to the users, please remember to post a summary of any useful responses to your questions.
              * To unsubscribe, send an email to majordomo@... with no subject and "unsubscribe ai-geostats" followed by "end" on the next line in the message body. DO NOT SEND Subscribe/Unsubscribe requests to the list
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