Convex Hull operation not specific enough

Question

I have yield data as point values, and I simply want to create the boundary around this layer. I have used the Minimum Bounding Geometry tool and selected Convex Hull to do this, however it maintains the corners as part of the polygon. Is there a way to automatically keep just the boundary of this file? Pictures below.

Here's the point file:

Here's what Convex Hull gives me:

And here's what I need to automate:

Answer 1

There are different ways to create concave hulls in QGIS (= alpha shapes, look at Introduction to Alpha Shapes (pdf), K. Fischer 2000 and On the creation of concave hulls and the various ways of doing that.(alpha-shapes), in French, which I take the figures).

• Concave Hull script in the processing toolbox, you can create holes

• The new Concave Hull plugin with clusters (if you want)

• The PgRouting Layer plugin of Anita Graser (underdark), based on PostGIS (A Closer Look at Alpha Shapes in pgRouting)

You can also use

• GRASS GIS (Create concave hull)

• OpenJUMP (Concave hull based on JTS extension)

• Python only (The fading shape of alpha , Drawing Boundaries In Python or Alpha shapes in Python, using the hull C program), examples in my scripts (in French), concave_hull1.py and concave_hull2.py

• R spatial with the alphahull package (there is also alphashape3D, for 3D "concave hulls"): look at my script (in French) alpha_shape.R

With alphashape3D

• PostGIS (PostGIS Concave Hull)

• SpatiaLite ( Delaunay Triangulation, Convex Hull and Concave Hull)