Visualising WKT geometry string in QGIS

Question

Is there a simple tool in QGIS to graphically visualise geometry formatted as text?

Example geometry:

POLYGON((571178 6337246,571178 6402217,598061 6402217,598061 6337246,571178 6337246))

Result:

A layer in QGIS showing the polygon from above.

The intention is to do quick and dirty visualisation for debugging purposes - I feel it is easier to relate to a graphical representation than a coordinate list.

Answer 1

Try the "QuickWKT" Plugin (see the official page: https://plugins.qgis.org/plugins/QuickWKT/).

Answer 2

Indeed there is! Look here for how to achieve it with the Add Delimited Text Layer plugin.

Essentially you create a CSV file (although you should use a delimiter other than comma), where one column is the WKT representation of your geometry. Then when you select that file in the plugin, it picks up that there is a WKT column, and does the right thing.

I can't vouch for its robustness, but the sample you gave works fine:

id|wkt
1|POLYGON((571178 6337246,571178 6402217,598061 6402217,598061 6337246,571178 6337246))

Answer 3

No Plugin required

In QGIS deploy a "Virtual Layer" through Layer > Add Layer > Add/Edit Virtual Layer....

In the Query window simply paste the following expression:

SELECT ST_GeomFromText('POLYGON((571178 6337246,571178 6402217,598061 6402217,598061 6337246,571178 6337246))')

or with an SRID code

SELECT ST_GeomFromText('POLYGON((571178 6337246,571178 6402217,598061 6402217,598061 6337246,571178 6337246))', 4326)

The result might look like this

One can also achieve the same result by means of PyQGIS:

from qgis.core import QgsVectorLayer, QgsProject

wkt_string = 'POLYGON((571178 6337246,571178 6402217,598061 6402217,598061 6337246,571178 6337246))'

layer = QgsVectorLayer(f"?query=SELECT ST_GeomFromText('{wkt_string}')", "result", "virtual")

if layer.isValid():
    QgsProject.instance().addMapLayer(layer)

---

References:

• PostGIS | ST_GeomFromText
• Wikipedia | Well-known text representation of geometry
• Creating Virtual Layer programmatically in QGIS

Answer 4

In QGIS >=3.18.3 we can copy one or multiple WKT strings into clipboard and paste them using Edit > Paste Feature As > Temporary Scratch Layer... into map canvas. CRS needs to be adjusted afterwards.

Answer 5

Quick and dirty: select the record in the table of attributes, Ctrl-C and then paste with Ctrl-V in a text editor. Along with attributes, you will also see the geometry as text.

Probably there are more elegant alternatives.

Answer 6

Use a virtual field

1. Go to "Layer properties" > "Fields"
2. Activate edit mode
3. Open "Field calculator"
4. Add a virtual field, using the expression geom_from_wkt($geometry)

Done