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Calibration and Datum Question

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  • g B
    This may be a lame question and maybe I m just not analyzing this enough on my own, but- From a DRG quad that my hometown appears in, I selected my town and
    Message 1 of 3 , Apr 1, 2001
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      This may be a lame question and maybe I'm just not analyzing this enough
      on my own, but-
      From a DRG quad that my hometown appears in, I selected my town and copied
      and pasted into Paint.
      The DRG datum is NAD27, but I was planning on getting calibration points
      just by sitting at intended points and averaging with my handheld using
      WGS84.
      Although the map is layed out in NAD27, for the purpose of just putzing
      around town, it really won't make any differance if I use WGS84 to collect
      the points and calibrate the map, will it?
      I would effectively be converting the map to WGS84, wouldn't I?
      Sure the streets won't line up perfectly, but not really worried about
      that as I am still learing Ozi and using the unregistered version at
      the moment.
      Thanks.

      --
      g B
      gpsgreg@...
      --
      "The incessant beep of the Global Positioning System is all the companionship
      I need."
      --Krusty The Clown

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    • Pieter Litchfield
      I may get this very wrong, but here s my theory- If you were to use the automatic registration of DRG s, you d have a problem. However, if you use Paint to
      Message 2 of 3 , Apr 1, 2001
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        I may get this very wrong, but here's my theory-
         
        If you were to use the automatic registration of DRG's, you'd have a problem.  However, if you use Paint to crop it to a smaller section, and then use the resulting bitmap for a basemap, the registration points are gone.  You will then pick two or more identifiable landmarks on the paper map, go there on the ground and get co-ordinates with the GPS set on WGS84, and then register the map with those points.  
         
        I believe that as long as you use the Ozi configuration menu to set the map datum to WGS84 and register those points, any subsequent waypoints (for example) transfered from the Ozi map should then be accurate.  Why?  Because the registration points you entered were based on the same datum (WGS84) in the GPS as the bitmap image in Ozi.  The registration of the DGR's would not effect anything since the cropping produced nothing more than an unregistered bitmap picture.  I'm guessing you could probably use any datum providing you used it to register the map, configure Ozi map settings, and used it in the GPS to navigate to the resulting waypoints.  The key is consistency.
         
        -----Original Message-----
        From: g B [mailto:gpsgreg@...]
        Sent: Sunday, April 01, 2001 2:57 PM
        To: OziUsers-L@yahoogroups.com
        Subject: [OziUsers-L] Calibration and Datum Question

        This may be a lame question and maybe I'm just not analyzing this enough
        on my own, but-
        From a DRG quad that my hometown appears in, I selected my town and copied
        and pasted into Paint.
        The DRG datum is NAD27, but I was planning on getting calibration points
        just by sitting at intended points and averaging with my handheld using
        WGS84.
        Although the map is layed out in NAD27, for the purpose of just putzing
        around town, it really won't make any differance if I use WGS84 to collect
        the points and calibrate the map, will it?
        I would effectively be converting the map to WGS84, wouldn't I?
        Sure the streets won't line up perfectly, but not really worried about
        that as I am still learing Ozi and using the unregistered version at
        the moment.
        Thanks.

        --
        g B
        gpsgreg@...
        --
        "The incessant beep of the Global Positioning System is all the companionship
        I need."
        --Krusty The Clown

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      • g B
        Pieter- I see that we are both here as well; good! That is pretty much what I had figured. I do think that it may cause a bit of differance as there may be a
        Message 3 of 3 , Apr 2, 2001
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          Pieter-
          I see that we are both here as well; good!
          That is pretty much what I had figured.
          I do think that it "may" cause a bit of differance as there may be a
          small differance in maps produced in NAD27 and WGS84, but as I said,
          with the unregistered (until the taxman sends that check!) version and
          just for horsing around, I'll live with that small error. Besides, it's
          more than likely with in the error of the handheld.
          That D cell battery pack in the PVC tube seems to be working; haven't
          done a "let it set and see how long it runs" test yet though.
          Thanks for the info on that too.
          GregB

          --
          g B
          gpsgreg@...

          "The incessant beep of the Global Positioning System is all the companionship
          I need."
          --Krusty The Clown




          ---- "Pieter Litchfield" <plitch@...> wrote:
          > I may get this very wrong, but here's my theory-
          >
          > If you were to use the automatic registration of DRG's, you'd have
          > a
          > problem. However, if you use Paint to crop it to a smaller section,
          > and
          > then use the resulting bitmap for a basemap, the registration points
          > are
          > gone. You will then pick two or more identifiable landmarks on the
          > paper
          > map, go there on the ground and get co-ordinates with the GPS set on
          > WGS84,
          > and then register the map with those points.
          >
          > I believe that as long as you use the Ozi configuration menu to set
          > the map
          > datum to WGS84 and register those points, any subsequent waypoints
          > (for
          > example) transfered from the Ozi map should then be accurate. Why?
          > Because
          > the registration points you entered were based on the same datum (WGS84)
          > in
          > the GPS as the bitmap image in Ozi. The registration of the DGR's
          > would not
          > effect anything since the cropping produced nothing more than an
          > unregistered bitmap picture. I'm guessing you could probably use any
          > datum
          > providing you used it to register the map, configure Ozi map settings,
          > and
          > used it in the GPS to navigate to the resulting waypoints. The key
          > is
          > consistency.
          >
          > -----Original Message-----
          > From: g B [mailto:gpsgreg@...]
          > Sent: Sunday, April 01, 2001 2:57 PM
          > To: OziUsers-L@yahoogroups.com
          > Subject: [OziUsers-L] Calibration and Datum Question
          >
          >
          > This may be a lame question and maybe I'm just not analyzing this
          > enough
          > on my own, but-
          > From a DRG quad that my hometown appears in, I selected my town and
          > copied
          > and pasted into Paint.
          > The DRG datum is NAD27, but I was planning on getting calibration
          > points
          > just by sitting at intended points and averaging with my handheld
          > using
          > WGS84.
          > Although the map is layed out in NAD27, for the purpose of just putzing
          > around town, it really won't make any differance if I use WGS84 to
          > collect
          > the points and calibrate the map, will it?
          > I would effectively be converting the map to WGS84, wouldn't I?
          > Sure the streets won't line up perfectly, but not really worried
          > about
          > that as I am still learing Ozi and using the unregistered version
          > at
          > the moment.
          > Thanks.
          >
          > --
          > g B
          > gpsgreg@...
          > --
          > "The incessant beep of the Global Positioning System is all the
          > companionship
          > I need."
          > --Krusty The Clown
          >
          > ___________________________________________________________________
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          >
          > To unsubscribe from this group, send an email to:
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          >
          >
          >
          > Your use of Yahoo! Groups is subject to the Yahoo! Terms of Service.
          >
          >

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