Figure 3.23 - Merge options
In the list, you will see the following options:
At First or At Last: Use the first or last selected vertex.
At Center: All vertices will merge using the median distance
between all of them.
At Cursor: The new vertice created will use the 3D Cursor
location.
Collapse: You will get islands of vertices merged based on the
distance between them. Each island will merge into a new vertex.
By distance: You will merge vertices based on the distance
between them. For instance, using a length of zero will remove all
duplicated vertices from a 3D model.
For the vertices from Figure 3.22, we can quickly fix the gap between
those two vertices with a Merge based on the median distance. Select
both vertices and with a right-click call the Context menu and pick
Merge → At Center (Figure 3.24).