<html>
<head>
<meta http-equiv="content-type" content="text/html; charset=UTF-8">
</head>
<body>
<blockquote type="cite"><b style="color: rgb(0, 0, 0); font-family:
"Times New Roman"; font-size: medium; font-style:
normal; font-variant-ligatures: normal; font-variant-caps:
normal; letter-spacing: normal; orphans: 2; text-align: start;
text-indent: 0px; text-transform: none; white-space: normal;
widows: 2; word-spacing: 0px; -webkit-text-stroke-width: 0px;
text-decoration-thickness: initial; text-decoration-style:
initial; text-decoration-color: initial;">davidlurie at
libero.it</b><span style="color: rgb(0, 0, 0); font-family:
"Times New Roman"; font-size: medium; font-style:
normal; font-variant-ligatures: normal; font-variant-caps:
normal; font-weight: 400; letter-spacing: normal; orphans: 2;
text-align: start; text-indent: 0px; text-transform: none;
white-space: normal; widows: 2; word-spacing: 0px;
-webkit-text-stroke-width: 0px; background-color: rgb(255, 255,
255); text-decoration-thickness: initial; text-decoration-style:
initial; text-decoration-color: initial; display: inline
!important; float: none;"><span> </span></span><a
href="mailto:qgis-user%40lists.osgeo.org?Subject=Re%3A%20%5BQgis-user%5D%20Request%20for%20exporting%20arcs%20from%20dxf%20to%20kml&In-Reply-To=%3C262521302.801307.1650790933783%40mail1.libero.it%3E"
title="[Qgis-user] Request for exporting arcs from dxf to kml"
style="font-family: "Times New Roman"; font-size:
medium; font-style: normal; font-variant-ligatures: normal;
font-variant-caps: normal; font-weight: 400; letter-spacing:
normal; orphans: 2; text-align: start; text-indent: 0px;
text-transform: none; white-space: normal; widows: 2;
word-spacing: 0px; -webkit-text-stroke-width: 0px;">davidlurie
at libero.it</a><br style="color: rgb(0, 0, 0); font-family:
"Times New Roman"; font-size: medium; font-style:
normal; font-variant-ligatures: normal; font-variant-caps:
normal; font-weight: 400; letter-spacing: normal; orphans: 2;
text-align: start; text-indent: 0px; text-transform: none;
white-space: normal; widows: 2; word-spacing: 0px;
-webkit-text-stroke-width: 0px; text-decoration-thickness:
initial; text-decoration-style: initial; text-decoration-color:
initial;">
<i style="color: rgb(0, 0, 0); font-family: "Times New
Roman"; font-size: medium; font-variant-ligatures: normal;
font-variant-caps: normal; font-weight: 400; letter-spacing:
normal; orphans: 2; text-align: start; text-indent: 0px;
text-transform: none; white-space: normal; widows: 2;
word-spacing: 0px; -webkit-text-stroke-width: 0px;
text-decoration-thickness: initial; text-decoration-style:
initial; text-decoration-color: initial;">Sun Apr 24 02:02:13
PDT 2022</i><span style="color: rgb(0, 0, 0); font-family:
"Times New Roman"; font-size: medium; font-style:
normal; font-variant-ligatures: normal; font-variant-caps:
normal; font-weight: 400; letter-spacing: normal; orphans: 2;
text-align: start; text-indent: 0px; text-transform: none;
white-space: normal; widows: 2; word-spacing: 0px;
-webkit-text-stroke-width: 0px; background-color: rgb(255, 255,
255); text-decoration-thickness: initial; text-decoration-style:
initial; text-decoration-color: initial; display: inline
!important; float: none;"></span>
<hr style="color: rgb(0, 0, 0); font-family: "Times New
Roman"; font-size: medium; font-style: normal;
font-variant-ligatures: normal; font-variant-caps: normal;
font-weight: 400; letter-spacing: normal; orphans: 2;
text-align: start; text-indent: 0px; text-transform: none;
white-space: normal; widows: 2; word-spacing: 0px;
-webkit-text-stroke-width: 0px; text-decoration-thickness:
initial; text-decoration-style: initial; text-decoration-color:
initial;">
<pre style="white-space: pre-wrap; color: rgb(0, 0, 0); font-style: normal; font-variant-ligatures: normal; font-variant-caps: normal; font-weight: 400; letter-spacing: normal; orphans: 2; text-align: start; text-indent: 0px; text-transform: none; widows: 2; word-spacing: 0px; -webkit-text-stroke-width: 0px; text-decoration-thickness: initial; text-decoration-style: initial; text-decoration-color: initial;">I always use default SR, Epsg 4326 - Wgs 84, the Google Earth one.
</pre>
</blockquote>
<br>
I Mauro,<br>
probably there is a misunderstanding here.<br>
<br>
Google Earth uses WGS84 datum as reference system for the
coordinates. However Google Earth represents such coordinates not in
a WGS84 Cartesian plane (as it happens with a WGS84 map in QGIS),
but in a globe / planisphere like representation called General
Perspective projection [1] [2].<br>
<br>
This means that a "circle" drawn on a layer in WGS84 CRS, and
represented in QGIS on a map/project with WGS84 CRS, will appear as
a circle. The same happens if the layer is exported as KML and
displayed in QGIS in map with the same WGS84 CRS or if exported as a
DXF and displayed with a CAD software.<br>
<br>
The "circle" will appears similar to an ellipse instead if the KML
layer is displayed using Google Earth, because the Google Earth
projection is not a WGS84 Cartesian plane, but a General Perspective
projection.<br>
<br>
The same happens for a polygon which resemble a "circle" in Google
Earth: if exported as KML it will appear similar to an ellipse in a
WGS84 map in QGIS.<br>
<br>
So you need to use the same (or very similar) projection to display
the geometries with the same (or very similar) shape.<br>
<br>
The General Perspective projection is an Azimuthal projection [3]
and is similar e.g. to an Orthographic projection [4] centred on a
suitably chosen centre.<br>
If your "circle" drawn in Google Earth is , e.g., centred at 15° E
Lon. and 40° N Lat., than you could create a custom Orthographic
projection with the following proj4 string and use such custom
projection as the map/project projection in order to properly
display it as a "circle" in QGIS:<br>
<br>
+proj=ortho +lat_0=40 +lon_0=15 +x_0=0 +y_0=0 +datum=WGS84 +units=m
+no_defs<br>
<br>
or you could similarly create e.g. a custom Azimuthal Equidistant
projection:<br>
<br>
+proj=aeqd +lat_0=40 +lon_0=15 +x_0=0 +y_0=0 +datum=WGS84 +units=m
+no_defs<br>
<br>
See also [3], [4] and [5].<br>
<br>
Regards.<br>
<br>
Andrea<br>
<br>
<br>
[1] <a class="moz-txt-link-freetext"
href="https://en.wikipedia.org/wiki/General_Perspective_projection">https://en.wikipedia.org/wiki/General_Perspective_projection</a><br>
[2]
<a class="moz-txt-link-freetext"
href="https://www.researchgate.net/publication/340162875_Google_Earth_and_Map_Projections_Google_Earth_i_kartografske_projekcije">https://www.researchgate.net/publication/340162875_Google_Earth_and_Map_Projections_Google_Earth_i_kartografske_projekcije</a><br>
[3] <a class="moz-txt-link-freetext" href="https://bnhr.xyz/2018/09/21/create-a-globe-in-QGIS.html">https://bnhr.xyz/2018/09/21/create-a-globe-in-QGIS.html</a><br>
[4]
<a class="moz-txt-link-freetext" href="https://docs.qgis.org/3.22/en/docs/user_manual/working_with_projections/working_with_projections.html">https://docs.qgis.org/3.22/en/docs/user_manual/working_with_projections/working_with_projections.html</a><br>
[5]
<a class="moz-txt-link-freetext" href="https://docs.qgis.org/3.22/en/docs/gentle_gis_introduction/coordinate_reference_systems.html">https://docs.qgis.org/3.22/en/docs/gentle_gis_introduction/coordinate_reference_systems.html</a><br>
</body>
</html>