Draw bounding region by list of points

Question

Suppose you have a list of data points, either in 2D or 3D; is it possible to plot the minimal bounding region containing all the points?

Ignoring holes etc.

my gut instinct is that InterpolationPoint might be the option to consider — MKF, Mar 06 '19 at 17:34
Exactly! is there a way to apply smoothing to it? and perhaps some opacity? — MKF, Mar 06 '19 at 17:45
Opacity: sure, it's somewhere in the options. What do you mean by "smoothing" though? Do you have an example in mind? — MarcoB, Mar 06 '19 at 17:48
It seems convexhullmesh will give a quite polygonal/linear shape. Is there anyway to somehow round the shape? — MKF, Mar 06 '19 at 17:50

score 8 · Answer 1 · answered Mar 06 '19 at 17:56

Given a set of random 3D points, you can create a mesh that represents the minimum bounding region using BoundingRegion[] or ConvexHullMesh[] as MarcoB suggested. ConvexHullMesh[] is probably the simplest, though BoundingRegion[] has some nice options for other sorts of regions like the smallest sphere or cuboid.

BlockRandom[SeedRandom[1234]; pts = RandomReal[{-1, 1}, {50, 3}];]
cvx = ConvexHullMesh[pts]
br = BoundingRegion[pts, "MinConvexPolyhedron"]

This should give you two meshes that look identical to this:

You can choose whichever function you prefer. It's also possible to show the points themselves along with the mesh:

Show[HighlightMesh[br, Style[2, Opacity[0.5]]], Graphics3D[Point[pts]]]

score 6 · Accepted Answer · answered Mar 06 '19 at 18:18

6

For the 2D case, you can use the shape of the joint to give rounded corners to your shape. For instance:

pts = RandomReal[{-5, 5}, {20, 2}];
ConvexHullMesh[pts]

hull

Retrieve the mesh expressed as a Polygon object and style to your liking:

Graphics[{
  Darker@Blue, 
  EdgeForm[{Darker@Blue, Thickness[0.09], JoinForm["Round"]}],
  Cases[Normal[chm["Graphics"]], _Polygon, All]
}]

styled

answered Mar 06 '19 at 18:18

MarcoB

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Awesome, thanks again! – MKF Mar 06 '19 at 18:32
@MKF You are welcome! – MarcoB Mar 06 '19 at 18:33

Draw bounding region by list of points

2 Answers2