'Re: [Qgis-user] How set real origin on a false origin dataset'

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List:       qgis-user
Subject:    Re: [Qgis-user] How set real origin on a false origin dataset
From:       Alexandre Neto <senhor.neto () gmail ! com>
Date:       2019-11-17 23:22:29
Message-ID: CA+H0G_GQoD0DLmQD=qt1_6tX+jx6gEvjax=ciN_My6+2G9vPzQ () mail ! gmail ! com
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Hi,

Another possible solution it's to create a custom projection where you
include the false origin information (false northing and false easting.
Then set your layers to use that custom projection.

For more information on how to create a custom projection in QGIS, check
this page of the official documentation:

https://docs.qgis.org/3.4/en/docs/user_manual/working_with_projections/working_with_projections.html#id12

For more information about the false northing and easting, check PROJ
documentation:

https://proj.org/usage/projections.html?highlight=false%20north#false-easting-northing

Alexandre Neto
QGIS Support
www.qcooperative.net

A domingo, 17/11/2019, 10:10, Lens Paul <paul.lens@gmx.com> escreveu:

> Hi Andrea,
>
> False origins happens often with local topographical surveys, with also a
> false altitude origin. Architectural plans are sometimes even more tricky:
> rotated, or with a centimetric or millimetric scale instead of a metric
> scale. A way is to transform the data with a CAD software when available.
> Even then, problems can arise e.g. when rescaling some objects.
>
> I suppose a workaround in your case  would be to use the "move" command
> and to snap to a point drawn at the correct coordinates. This could be
> cumbersome when there are many layers to edit, which is often the case,
> unless you import the dxf as a unique layer....
>
> If your data consist merely of point data (no polylines), it should be
> possible, after conversion of the dxf in a shapefile, to create the  X, Y
> attributes using the field calculator, and to recalculate these attributes
> with the same tool.
>
> In the case of polylines, there is the possibility to extract vertices.
> But I do not know if there is a possibility to recreate the polylines after
> the recalculation of the X, Y attributes.
>
> Dxf conversion is a complicated subject. The evolution of the capabilities
> of QGIS in that field is amazing. Many thanks to the developers for that.
>
> Hope this helps,
>
> Paul
> Le 13/11/2019 Ă  14:04, Andrea Peri a ĂŠcrit :
>
> Hi,
> We have a dxf containings geograph data in false.origin .
> I'm searching a solution to put a kind of origin (x,y) to sum to every
> point of the data. Is possible to set an origin.to a dataset in qgis ?
>
> Thx.
> Andrea.
>
>
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[Attachment #5 (text/html)]

<div dir="auto"><div dir="auto">Hi,<div dir="auto"><br></div><div dir="auto">Another \
possible solution it&#39;s to create a custom projection where you include the false \
origin information (false northing and false easting. Then set your layers to use \
that custom projection.</div><div dir="auto"><br></div><div dir="auto">For more \
information on how to create a custom projection in QGIS, check this page of the \
official documentation:</div><div dir="auto"><br></div><div dir="auto"><a \
href="https://docs.qgis.org/3.4/en/docs/user_manual/working_with_projections/working_with_projections.html#id12" \
target="_blank" rel="noreferrer">https://docs.qgis.org/3.4/en/docs/user_manual/working_with_projections/working_with_projections.html#id12</a></div><div \
dir="auto"><br></div><div dir="auto">For more information about the false northing \
and easting, check PROJ documentation:</div><div dir="auto"><br></div><div \
dir="auto"><a href="https://proj.org/usage/projections.html?highlight=false%20north#fa \
lse-easting-northing">https://proj.org/usage/projections.html?highlight=false%20north#false-easting-northing</a><br></div><div \
dir="auto"><br></div><div dir="auto">Alexandre Neto</div><div dir="auto">QGIS \
Support</div><div dir="auto"><a \
href="http://www.qcooperative.net">www.qcooperative.net</a></div><div \
dir="auto"><br></div><div dir="auto"><br></div></div><br><div \
class="gmail_quote"><div dir="ltr" class="gmail_attr">A domingo, 17/11/2019, 10:10, \
Lens Paul &lt;<a href="mailto:paul.lens@gmx.com" target="_blank" \
rel="noreferrer">paul.lens@gmx.com</a>&gt; escreveu:<br></div><blockquote \
class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc \
solid;padding-left:1ex">  

  <div text="#000000" bgcolor="#FFFFFF">
    <p>Hi Andrea,<br>
    </p>
    <p>False origins happens often with local topographical surveys,
      with also a false altitude origin. Architectural plans are
      sometimes even more tricky: rotated, or with a centimetric or
      millimetric scale instead of a metric scale. A way is to transform
      the data with a CAD software when available. Even then, problems
      can arise e.g. when rescaling some objects.</p>
    <p>I suppose a workaround in your case   would be to use the &quot;move&quot;
      command and to snap to a point drawn at the correct coordinates.
      This could be cumbersome when there are many layers to edit, which
      is often the case, unless you import the dxf as a unique layer....</p>
    <p>If your data consist merely of point data (no polylines), it
      should be possible, after conversion of the dxf in a shapefile, to
      create the   X, Y attributes using the field calculator, and to
      recalculate these attributes with the same tool. <br>
    </p>
    <p>In the case of polylines, there is the possibility to extract
      vertices. But I do not know if there is a possibility to recreate
      the polylines after the recalculation of the X, Y attributes.<br>
    </p>
    <p>Dxf conversion is a complicated subject. The evolution of the
      capabilities of QGIS in that field is amazing. Many thanks to the
      developers for that.<br>
    </p>
    <p>Hope this helps,</p>
    <p>Paul<br>
    </p>
    <div>Le 13/11/2019 Ă  14:04, Andrea Peri a
      ĂŠcrit  :<br>
    </div>
    <blockquote type="cite">

      <div dir="auto">Hi,
        <div dir="auto">We have a dxf containings geograph data in
          false.origin .</div>
        <div dir="auto">I&#39;m searching a solution to put a kind of origin
          (x,y) to sum to every point of the data. Is possible to set an
          <a href="http://origin.to" rel="noreferrer noreferrer" \
target="_blank">origin.to</a>  a dataset in qgis ?</div>
        <div dir="auto"><br>
        </div>
        <div dir="auto">Thx.</div>
        <div dir="auto">Andrea.</div>
        <div dir="auto"><br>
        </div>
      </div>
      <br>
      <fieldset></fieldset>
      <pre>_______________________________________________
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