Is it possible (without writing Python code – sorry I'm not a developer) to create a point layer from a polygon layer but ensure the point is within the polygon? The ftools centroid tool is cool but some centroids are created outside the polygon (i.e. irregular polygon). In ArcGIS there is a "Feature to Point" tool similar to the ftools 'polygon centroids' tool but has a checkbox to force the point to be within the polygon.
Create a Point Within a Polygon in QGIS – How to
pointqgis
Related Solutions
You can join the polylines by editing the layer, selecting all the lines (all of them or by attribute) and then click the 'Merge Features' tool:
To find the midpoint, calculate distance of lines, then use point along line tools to put a point at distance/2 along each line.
I've only found this work-around so far:
- You need to load the polygon layer twice.
- The lower layer is styled using the Centroid Fill option.
- The upper layer uses the same style but without the Centroid Fill layer.
- Enable labeling for the upper layer. Placement should be 'horizontal' or 'free'.
- In Print Composer, delete the upper layer from the legend items list.
This is far from optimal, but I don't think this special feature is going to be implemented soon into the renderer.
Best Answer
If you do not care about whether the point is a centroid or not, just use Vector -> ResearchTools -> Random Points. You may define to place a single point per each polygon in a layer. Also you may create centroids for initial polygons, delete points that do not intersect any polygon, save polygons without points as a separate layer, create random points for this polygosns and in the end copy these random points to centroids layer.