In QGIS it’s possible to convert a points layer to a polygons layer in just a few steps. To do so there are some minimum requirements for the points layer, because QGIS has to know which points should be grouped to a polygon and in which order these points must form a polygon. To illustrate this I have created a test layer with 7 points. I added two new fields: “polygon” and “order”. The field “polygon” indicates which points have to form a polygon together. In this example the result should be two polygons (1 & 2). The field “order” indicates in which order the points should be connected to form a polygon. In this example the result will be a triangle and a quadrangle (quadrilateral).
The first step we will do, is convert the points layer to a polylines layer. To do this we locate the “Points to path” tool in the Processing toolbox. We open this tool by double clicking it.
A window opens where we can set how the polylines layer should be created. In the “Order field” combo box select “order” and in the “Group field” combo box we select “polygon”. In the case that all the points should form one big polygon, the combo box “Group field” can be left empty. In the “Paths” box we set where the polylines layer should be saved.
If we then click on the “Run” button, a new layer is added to our project that contains two polylines.
To convert this polylines layer to a polygons layer, we will locate the “Lines to polygons” tool in the Processing Toolbox. We open this tool by double clicking it.
A window opens where we can set which polylines layer we want to use as “Input layer”. In this case that’s our previously created polylines layer. In the “Polygons” box we can set where we want to save the polygons layer.
If we then click on the “Run” button, a new layer is added to our project that contains two polygons.