Welding line vertices or resume creating new line from end of old one in QGIS?

Question

I'm creating a long and detailed (historical) border, and I guess it will take days.

How can I weld lines, or just resume creating a new one directly from the end of old fragment using QGIS?

When I click 'edit' and that small '+' at the end it just adds one(why?) segment and then stops without me right clicking it.

Edit: I've found 'Advanced Line Editor' plugin, but still it doesn't connect lines/vertices, however splitting works.

Answer 1

I think you are using QGIS 3.x because you mentioned the small +. If you want to extend the line you need to click inside the red circle node and move slightly your pointer (mouse) to become square shape so that it will enable you to extend the line:

• Put the mouse over the node, it will become a big red circle

• Click inside the big red circle and move your pointer (mouse) a little (almost one pixel) until it becomes pink square:

• The pink square means that the node is selected and you can directly move the node to extend the line:

However, using the + sign make it easy to add a new line snapped to the existing line, which enables you to extend the line in same/different directions:

and it is still one line not two lines:

Answer 2

I think the tool you are looking for to "resume creating a new one directly from the end of old fragment " is Continue Features, and that is described in the Help page titled Extending a line by sketching:

You can extend a line by digitizing new segments at the end of the existing sketch. For example, you might use this when updating a road by tracing over aerial photographs. You can resume sketching the shape of an existing line from the last vertex and add the new length to the road segment.

Answer 3

The "welding" feature you're looking for is available on the Advanced Digitizing Toolbar, with the "merge selected features" button. This feature will join together two or more features in the same layer.

The starting end vertices of the two lines must be identical, so turn on snapping and use the Vertex Tool to move one of the the vertices onto the other.

Select both lines, and click the "merge selected features" button.

Answer 4

Ok I figured it out.

@ahmadhanb: Yes, I'm using QGIS 3.4. I'm clicking it, but it doesn't turn pink, don't know what I'm doing wrong

cks@ "Merge Selected Features" is (was) always grayed out, I was selecting vertexes, they're turning blue, but that button doesn't worked

..until

I clicked Select Feature by area. Now it works :-)