Hi,
You can create a geometry from WKT if you have x and y fields using and
expression in the field calculator.
geom_from_wkt('POINT('||"x"||' '||"y"||')')
https://en.wikipedia.org/wiki/Well-known_text_representation_of_geometry
Nicolas Cadieux
> Le 13 nov. 2020 à 09:07, Andreas Neumann <[email protected]> a écrit :
>
>
> Hi
>
> 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.
>
> 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
> https://docs.qgis.org/testing/en/docs/user_manual/managing_data_source/create_layers.html#creating-virtual-layers
>
> 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.
>
> 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).
>
> Hope this helps you,
>
> Andreas
>
>> Am 13.11.20 um 14:52 schrieb L.W.:
>> Does it works on Layers with no geometry?
>>
>> My layers do not have a geometry.
>>
>>
>>
>> Am 13.11.2020 um 11:56 schrieb Andreas Neumann:
>>> Yes, you need point data to start from, but then vectors can bei/are
>>> generated from the attributes you mentioned.
>>>
>>> Andreas
>>>
>>>> Am 13.11.20 um 11:47 schrieb L.W.:
>>>> from the docs ...
>>>>
>>>> ****It can only be used to render point data****
>>>>
>>>> 12.2.2.2.6. The Vector Field Marker
>>>>
>>>> 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.
>>>>
>>>> The vector field is defined by attributes in the data, which can represent
>>>> the field either by:
>>>>
>>>> cartesian components (x and y components of the field)
>>>> or polar coordinates: in this case, attributes define Length and Angle.
>>>> The angle may be measured either clockwise from north, or Counterclockwise
>>>> from east, and may be either in degrees or radians.
>>>> or as height only 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.
>>>> The magnitude of field
>>>>
>>>>
>>>>
>>>> Am 13.11.2020 um 11:34 schrieb Andreas Neumann:
>>>>> Or even easier: use the "Vector Field Marker":
>>>>>
>>>>> https://docs.qgis.org/3.10/en/docs/user_manual/style_library/symbol_selector.html?#the-vector-field-marker
>>>>>
>>>>>
>>>>>> Am 13.11.20 um 11:33 schrieb Andreas Neumann:
>>>>>> Hi,
>>>>>>
>>>>>> Yes - you can use Geometry Generators for that. Use the make_point() and
>>>>>> make_line() expressions for that.
>>>>>>
>>>>>> See
>>>>>> https://docs.qgis.org/3.10/en/docs/user_manual/style_library/symbol_selector.html?highlight=geometry%20generator#the-geometry-generator
>>>>>>
>>>>>> Greetings,
>>>>>> Andreas
>>>>>>
>>>>>>> Am 13.11.20 um 11:26 schrieb L.W.:
>>>>>>> Hi,
>>>>>>>
>>>>>>> is it possible to draw automatically a line between two points defined
>>>>>>> by 4 fields (x1,y1 - x2,y2) in an attributetable?
>>>>>>>
>>>>>>> but I do not want to add a line-layer based on this table nor want to
>>>>>>> draw the line by hand.
>>>>>>>
>>>>>>> thanks
>>>>>>>
>>>>>>> _______________________________________________
>>>>>>> Qgis-user mailing list
>>>>>>> [email protected]
>>>>>>> List info: https://lists.osgeo.org/mailman/listinfo/qgis-user
>>>>>>> Unsubscribe: https://lists.osgeo.org/mailman/listinfo/qgis-user
>>>>>> _______________________________________________
>>>>>> Qgis-user mailing list
>>>>>> [email protected]
>>>>>> List info: https://lists.osgeo.org/mailman/listinfo/qgis-user
>>>>>> Unsubscribe: https://lists.osgeo.org/mailman/listinfo/qgis-user
>>>>> _______________________________________________
>>>>> Qgis-user mailing list
>>>>> [email protected]
>>>>> List info: https://lists.osgeo.org/mailman/listinfo/qgis-user
>>>>> Unsubscribe: https://lists.osgeo.org/mailman/listinfo/qgis-user
>>>>
>>>>
>>>> _______________________________________________
>>>> Qgis-user mailing list
>>>> [email protected]
>>>> List info: https://lists.osgeo.org/mailman/listinfo/qgis-user
>>>> Unsubscribe: https://lists.osgeo.org/mailman/listinfo/qgis-user
>>>
>>>
>>> _______________________________________________
>>> Qgis-user mailing list
>>> [email protected]
>>> List info: https://lists.osgeo.org/mailman/listinfo/qgis-user
>>> Unsubscribe: https://lists.osgeo.org/mailman/listinfo/qgis-user
>>
>>
>> _______________________________________________
>> Qgis-user mailing list
>> [email protected]
>> List info: https://lists.osgeo.org/mailman/listinfo/qgis-user
>> Unsubscribe: https://lists.osgeo.org/mailman/listinfo/qgis-user
> _______________________________________________
> Qgis-user mailing list
> [email protected]
> List info: https://lists.osgeo.org/mailman/listinfo/qgis-user
> Unsubscribe: https://lists.osgeo.org/mailman/listinfo/qgis-user
_______________________________________________
Qgis-user mailing list
[email protected]
List info: https://lists.osgeo.org/mailman/listinfo/qgis-user
Unsubscribe: https://lists.osgeo.org/mailman/listinfo/qgis-user
