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Concave vs Convex — How to merge polygons

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What is the difference?

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A concave hull is essentially a shape that has dents or caves in it, like a cave in a mountain or a dimple in a ball. A convex hull, on the other hand, is a shape that is round and smooth, like a beach ball or a basketball.
 
Imagine you have a bunch of pebbles on a flat surface. If you put a rubber band around all the pebbles, the rubber band would make a convex hull because it is round and smooth and doesn't have any dents or caves in it. If you put a piece of paper over the pebbles and cut out the shape of the pebbles with scissors, the paper would make a concave hull because it might have some dents or caves in it where the scissors went around the pebbles.
 
Convex and concave hulls are used to help us understand and work with shapes and patterns. They can be used to find trends in data, simplify complicated shapes, and do other things with points in space.

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Merge Two Polygons

Create the polygons

  1. Create two polygons.
    To learn how to create the overlays, visit these links
     

    Rectangle Tool—Draw a rectangle

    Circle Tool—Draw a circle

    Draw a polygon - (Polygon Tool)

     
 

Merge two Polygons

  1. Right-click on the polygon you want to merge.
    OR
    From the Layers Panel, click on the 3 dots to the right of the polygon displaying the tooltip: "More actions".
     
  2. From the Overlay list of options, click on Merge Polygons.
    You will see a window appear with a list of all of your polygons.
     
  3. Select the polygon you want to merge the first one with.
    You will see the "How to Merge?" options appear.
     
  4. Select the type of merge:
    • Concave
    • Convex
    • Precise
      Note: To use the Precise option, the polygons will need to be touching. This will only merge the polyons at the point of contact.
    In Map View, you will see that the merge has been completed.
 
 

Merge a Group of Polygons

Create the polygons

  1. Create a group of polygons.
    To learn how to create the overlays, visit these links
     

    Rectangle Tool—Draw a rectangle

    Circle Tool—Draw a circle

    Draw a polygon - (Polygon Tool)

     
 

Add the overlays to a folder

  1. At the top of the Layers Panel, click on the Folder Icon displaying the tooltip: "Add Group".
    You will see the folder added to the Layers Panel. Note the name of the folder. For example: "Group a".
     
  2. Click and drag each overlay’s row into the folder.
    The folder now holds a set of overlays, so the folder is considered a Group.
    To learn more about grouping overlays, see; Grouping markers/elements by using folders.

Bulk merge the overlays

  1. From the Layers Panel, click on the 3 dots to the right of the folder displaying the tooltip: "More actions".
     
  2. From the Group Shape list of options, click on Polygon Wrap (Hull).
     
  3. Select the type of merge:
    • Concave
    • Convex
    In Map View, you will see that the merge has been completed.
 
 

Related

Create a convex hull from a group of overlays - "Hulls Convex"

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