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<p>Hi</p>
<p>Neither GeometryGenerators nor Vector Field Markers work on
tables without geometry, unfortunately. You didn't inform us, that
you don't have geometry in your table.<br>
</p>
<p>You can, however, create a "Virtual Layer" and write some SQL to
create a geometry from your attributes: menu "Layer" -->
"Create Layer" --> "New Virtual Layer" - where you can use your
existing tables and create a new geometry column with SQL. See
<a class="moz-txt-link-freetext" href="https://docs.qgis.org/testing/en/docs/user_manual/managing_data_source/create_layers.html#creating-virtual-layers">https://docs.qgis.org/testing/en/docs/user_manual/managing_data_source/create_layers.html#creating-virtual-layers</a></p>
<p>Or, if your table is a CSV file, then you can assign attribute
columns to a point geometry and then just hide the point rendering
if you don't need it.<br>
</p>
<p>This is an unfortunate limitation of QGIS, that there is no
"easy" way to add a geometry column to table that doesn't have
geometry (or if it is possible, then I don't know it).</p>
<p>Hope this helps you,</p>
<p>Andreas<br>
</p>
<div class="moz-cite-prefix">Am 13.11.20 um 14:52 schrieb L.W.:<br>
</div>
<blockquote type="cite"
cite="mid:7f9befd5-d44c-8aec-7036-71461c7964e2@gmx.de">
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<p>Does it works on Layers with no geometry?</p>
<p>My layers do not have a geometry.</p>
<p><br>
</p>
<div class="moz-cite-prefix">Am 13.11.2020 um 11:56 schrieb
Andreas Neumann:<br>
</div>
<blockquote type="cite"
cite="mid:80d2b9f3-0896-999d-a5ab-17ad4573d522@carto.net">
<meta http-equiv="Content-Type" content="text/html;
charset=UTF-8">
<p>Yes, you need point data to start from, but then vectors can
bei/are generated from the attributes you mentioned.</p>
<p>Andreas<br>
</p>
<div class="moz-cite-prefix">Am 13.11.20 um 11:47 schrieb L.W.:<br>
</div>
<blockquote type="cite"
cite="mid:cd1f5b7c-4703-530f-d5b7-b51caa5632d5@gmx.de">
<meta http-equiv="Content-Type" content="text/html;
charset=UTF-8">
<p>from the docs ...</p>
<p>****It can only be used to render point data****</p>
<h4 style="box-sizing: border-box; margin-top: 0px;
font-weight: 700; font-family: "Roboto Slab",
ff-tisa-web-pro, Georgia, Arial, sans-serif; font-size:
18.4px; color: rgb(64, 64, 64); 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; background-color: rgb(252, 252, 252);
text-decoration-style: initial; text-decoration-color:
initial;"><a class="toc-backref"
href="https://docs.qgis.org/3.10/en/docs/user_manual/style_library/symbol_selector.html?#id15"
style="box-sizing: border-box; color: rgb(64, 64, 64);
text-decoration: none; cursor: pointer; outline-width: 0px
!important; user-select: auto !important;"
moz-do-not-send="true"><span class="section-number"
style="box-sizing: border-box;">12.2.2.2.6.<span> </span></span>The
Vector Field Marker</a></h4>
<p class="" style="box-sizing: border-box; line-height: 24px;
font-size: 16px; margin: 0px 0px 24px; color: rgb(64, 64,
64); font-family: Lato, proxima-nova, "Helvetica
Neue", Arial, sans-serif; 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(252,
252, 252); text-decoration-style: initial;
text-decoration-color: initial;">The vector field marker is
used to display vector field data such as earth deformation,
tidal flows, and the like. It displays the vectors as lines
(preferably arrows) that are scaled and oriented according
to selected attributes of data points. ****It can only be
used to render point data****; line and polygon layers are
not drawn by this symbology.</p>
<p style="box-sizing: border-box; line-height: 24px;
font-size: 16px; margin: 0px 0px 24px; color: rgb(64, 64,
64); font-family: Lato, proxima-nova, "Helvetica
Neue", Arial, sans-serif; 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(252,
252, 252); text-decoration-style: initial;
text-decoration-color: initial;">The vector field is defined
by attributes in the data, which can represent the field
either by:</p>
<ul class="simple" style="box-sizing: border-box; margin: 0px
0px 24px; padding: 0px; list-style: disc; line-height: 24px;
color: rgb(64, 64, 64); font-family: Lato, proxima-nova,
"Helvetica Neue", Arial, sans-serif; font-size:
16px; 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(252, 252, 252); text-decoration-style:
initial; text-decoration-color: initial;">
<li style="box-sizing: border-box; list-style: disc;
margin-left: 24px;">
<p style="box-sizing: border-box; line-height: 24px;
font-size: 16px; margin: 0px;"><strong
style="box-sizing: border-box; font-weight: 700;">cartesian</strong><span> </span>components
(<code class="docutils literal notranslate"
style="box-sizing: border-box; font-family:
SFMono-Regular, Menlo, Monaco, Consolas,
"Liberation Mono", "Courier New",
Courier, monospace; font-size: 12px; white-space:
nowrap; max-width: 100%; background: rgb(255, 255,
255); border: 1px solid rgb(225, 228, 229); padding:
2px 5px; color: rgb(231, 76, 60); overflow-x: auto;"><span
class="pre" style="box-sizing: border-box;">x</span></code><span> </span>and<span> </span><code
class="docutils literal notranslate"
style="box-sizing: border-box; font-family:
SFMono-Regular, Menlo, Monaco, Consolas,
"Liberation Mono", "Courier New",
Courier, monospace; font-size: 12px; white-space:
nowrap; max-width: 100%; background: rgb(255, 255,
255); border: 1px solid rgb(225, 228, 229); padding:
2px 5px; color: rgb(231, 76, 60); overflow-x: auto;"><span
class="pre" style="box-sizing: border-box;">y</span></code><span> </span>components
of the field)</p>
</li>
<li style="box-sizing: border-box; list-style: disc;
margin-left: 24px;">
<p style="box-sizing: border-box; line-height: 24px;
font-size: 16px; margin: 0px;">or<span> </span><strong
style="box-sizing: border-box; font-weight: 700;">polar</strong><span> </span>coordinates:
in this case, attributes define<span> </span><code
class="docutils literal notranslate"
style="box-sizing: border-box; font-family:
SFMono-Regular, Menlo, Monaco, Consolas,
"Liberation Mono", "Courier New",
Courier, monospace; font-size: 12px; white-space:
nowrap; max-width: 100%; background: rgb(255, 255,
255); border: 1px solid rgb(225, 228, 229); padding:
2px 5px; color: rgb(231, 76, 60); overflow-x: auto;"><span
class="pre" style="box-sizing: border-box;">Length</span></code><span> </span>and<span> </span><code
class="docutils literal notranslate"
style="box-sizing: border-box; font-family:
SFMono-Regular, Menlo, Monaco, Consolas,
"Liberation Mono", "Courier New",
Courier, monospace; font-size: 12px; white-space:
nowrap; max-width: 100%; background: rgb(255, 255,
255); border: 1px solid rgb(225, 228, 229); padding:
2px 5px; color: rgb(231, 76, 60); overflow-x: auto;"><span
class="pre" style="box-sizing: border-box;">Angle</span></code>.
The angle may be measured either clockwise from north,
or Counterclockwise from east, and may be either in
degrees or radians.</p>
</li>
<li style="box-sizing: border-box; list-style: disc;
margin-left: 24px;">
<p style="box-sizing: border-box; line-height: 24px;
font-size: 16px; margin: 0px;">or as<span> </span><strong
style="box-sizing: border-box; font-weight: 700;">height
only</strong><span> </span>data, which displays a
vertical arrow scaled using an attribute of the data.
This is appropriate for displaying the vertical
component of deformation, for example.</p>
</li>
</ul>
<p style="box-sizing: border-box; line-height: 24px;
font-size: 16px; margin: 0px 0px 24px; color: rgb(64, 64,
64); font-family: Lato, proxima-nova, "Helvetica
Neue", Arial, sans-serif; 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(252,
252, 252); text-decoration-style: initial;
text-decoration-color: initial;">The magnitude of field</p>
<p style="box-sizing: border-box; line-height: 24px;
font-size: 16px; margin: 0px 0px 24px; color: rgb(64, 64,
64); font-family: Lato, proxima-nova, "Helvetica
Neue", Arial, sans-serif; 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(252,
252, 252); text-decoration-style: initial;
text-decoration-color: initial;"><br>
</p>
<div class="moz-cite-prefix">Am 13.11.2020 um 11:34 schrieb
Andreas Neumann:<br>
</div>
<blockquote type="cite"
cite="mid:9d5955ce-6f3b-14ba-b27c-5f409d3382cd@carto.net">Or
even easier: use the "Vector Field Marker": <br>
<br>
<a class="moz-txt-link-freetext"
href="https://docs.qgis.org/3.10/en/docs/user_manual/style_library/symbol_selector.html?#the-vector-field-marker"
moz-do-not-send="true">https://docs.qgis.org/3.10/en/docs/user_manual/style_library/symbol_selector.html?#the-vector-field-marker</a>
<br>
<br>
Am 13.11.20 um 11:33 schrieb Andreas Neumann: <br>
<blockquote type="cite">Hi, <br>
<br>
Yes - you can use Geometry Generators for that. Use the
make_point() and make_line() expressions for that. <br>
<br>
See <a class="moz-txt-link-freetext"
href="https://docs.qgis.org/3.10/en/docs/user_manual/style_library/symbol_selector.html?highlight=geometry%20generator#the-geometry-generator"
moz-do-not-send="true">https://docs.qgis.org/3.10/en/docs/user_manual/style_library/symbol_selector.html?highlight=geometry%20generator#the-geometry-generator</a><br>
<br>
Greetings, <br>
Andreas <br>
<br>
Am 13.11.20 um 11:26 schrieb L.W.: <br>
<blockquote type="cite">Hi, <br>
<br>
is it possible to draw automatically a line between two
points defined <br>
by 4 fields (x1,y1 - x2,y2) in an attributetable? <br>
<br>
but I do not want to add a line-layer based on this
table nor want to <br>
draw the line by hand. <br>
<br>
thanks <br>
<br>
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