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QGIS ‘detects’ a shared boundary in a polygon mosaic and you only have to move the vertex once and QGIS will take care about updating the other boundary. The second topological option in the Avoid Int. column, called Avoid intersections of new polygons avoids overlaps in polygon mosaics.
Do you have to digitize second polygon in QGIS?
If you already have one polygon, it is possible with this option to digitize the second one such that both intersect, and QGIS then cuts the second polygon to the common boundary. The advantage is that you don’t have to digitize all vertices of the common boundary.
Is there a way to snap on an intersection in QGIS?
Another option is to use Enable snapping on intersection . It allows to snap on an intersection of background layers, even if there’s no vertex on the intersection. By default, QGIS loads layers read-only: This is a safeguard to avoid accidentally editing a layer if there is a slip of the mouse.
Why does QGIS load layers read-only by default?
By default, QGIS loads layers read-only: This is a safeguard to avoid accidentally editing a layer if there is a slip of the mouse. However, you can choose to edit any layer as long as the data provider supports it, and the underlying data source is writable (i.e. its files are not read-only).
If you already have one polygon, it is possible with this option to digitize the second one such that both intersect, and QGIS then cuts the second polygon to the boundary of the existing one. The advantage is that you don’t have to digitize all vertices of the common boundary.
What happens if somebody edits the same feature in QGIS?
This version of QGIS does not track if somebody else is editing the same feature at the same time as you are. The last person to save its edits wins. For an optimal and accurate edit of the vector layer geometries, we need to set an appropriate value of snapping tolerance and search radius for features vertices.
Is there a way of auto increment for the ID column in QGIS 3?
In QGIS 3 there is now a native tool which can be used to do this exact job and it is called “Add autoincremental field” No need to use an expression in the field calculator or do any coding but nevertheless these are all still very useful and good to know.