This question is an exact duplicate of:
I am very new at using QGIS. I have the standard installation (no additional plug-ins). I have several polygons and each polygon is formed by a number of segments. What I am trying to do is to connect the polygons with each other with new lines that I create. So for example I have two polygons (left and right are the two polygons) and I want to create a new segment from one point of the first polygon to another point on the second polygon.
I am using the "catch" function so it catches the points automatically. I create the segment (zoom in BEFORE saving, everything ok) BUT when I click on "save changes" (for the segments layer) both ends of the new segment jump from their position (zoom in AFTER saving, not ok) and are not staying on the polygon-points they were captured on. Why? Also the identification chart of the new segment is empty and doesn't adopt the start and endnode. http://postimage.org/gallery/5fh42dqk/
I than tried to create a segment and type in manually the StartNode and EndNode but QGIS doesn't connect the two nodes at all. How does this work? Do I need a plugin for this?
Hope you can help me on this. Would appreciate it. Thank you, Tud
EDIT: So i narrowed it down to a round up. When i save the changes i made to the layer (so NOT the project save) QGIS rounds up the coordinates to an accuracy of six decimals. Why is that and how can i disable it? Thank you