<html><head><meta http-equiv="content-type" content="text/html; charset=utf-8"></head><body dir="auto">Hi,<div><br><div>Only AutoCAD Map3D was a certain comprehension of what a CRS is. To my knowledge all other Autodesk Pilotdo not used any CRS. It is my honest opinion that AutoCAD Map is the worst attempt to make a GIS.<br><br><div dir="ltr">Nicolas Cadieux<div><a href="https://gitlab.com/njacadieux">https://gitlab.com/njacadieux</a></div></div><div dir="ltr"><br><blockquote type="cite">Le 21 nov. 2021 à 13:52, Bernd Vogelgesang <bernd.vogelgesang@gmx.de> a écrit :<br><br></blockquote></div><blockquote type="cite"><div dir="ltr">
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<br>
<div class="moz-cite-prefix">On 21.11.21 15:35, Nicolas Cadieux
wrote:<br>
</div>
<blockquote type="cite" cite="mid:181c8763-a9dd-8c58-42e1-4f2da49be5d8@gmail.com">Hi,
<br>
<br>
.dwg or dxf have no CRS. They can be in inches, feet, mm, cm,
m... Usually meter in a local CRS like a local WGS84 UTM ZONE is
used. You can usually find this in the metadata if available.
<br>
<br>
Nicolas
<br>
</blockquote>
<p>I have no deep technical insight into dwg or dxf, but I am pretty
sure that those CAD-"products" are able to be produced with valid
coordinates, fitting to a common CRS. Most people using
CAD-systems simply seem to be either too stupid for that, or just
do not care.</p>
<p>One of the reasons, CAD-"data" is produced with a local reference
system instead with a normal CRS is, according to an CAD-operator
I once asked about this, that some CAD-systems just slow down to
in-operability when using real-world coordinates because of the
huge numbers, compared to the small coordinates in their own
system.<br>
<br>
So, I would not even try to fix this, but instead ask those guys
to stop scratching their balls and better send you proper
real-world data and tell you which CRS they are in . The handling
of this "data" is punishment enough afterwords.<br>
</p>
<p>Hope my dislike for this "technology" was not too obvious ;)<br>
</p>
<p>Cheers,</p>
<p>Bernd</p>
<p><br>
</p>
<blockquote type="cite" cite="mid:181c8763-a9dd-8c58-42e1-4f2da49be5d8@gmail.com">
<br>
On 2021-11-21 9:07 a.m., Greg Troxel wrote:
<br>
<blockquote type="cite">Boaz Bar Ilan<a class="moz-txt-link-rfc2396E" href="mailto:boazprosie@gmail.com"><boazprosie@gmail.com></a>
writes:
<br>
<br>
<blockquote type="cite">i always have problem importing dwg or
dxf . the layers dont fit the
<br>
coardinations and even when i set the layers crs it doesnt
work.
<br>
</blockquote>
I am far from an expert, but recently tried to deal with a dwg.
<br>
<br>
My impression is that they are almost always in local
coordinates, and
<br>
the path to success is something like using GeoScience plugin to
define
<br>
a local CRS based on control points where you know global
coordinates
<br>
and local, and then to use that CRS for the data.
<br>
<br>
I recently imported some "PNEZD" data (csv with point it,
northing,
<br>
easting, vertical, and description, all in an unspecified local
grid,
<br>
from a total station data collector) and used geoscience to
align it
<br>
wtih RTK obsservations of a few points, and things fit quite
well.
<br>
<br>
How are you getting dwg? Are you using the proprietary dwg
library with
<br>
gdal, or is there some open source path?
<br>
<br>
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