Perimeter in polygon

[sunpit]

Hello, I have a set of polygons, in turn formed by several polygons. Let's suppose a large polygon formed by three smaller polygons. Is there any method to know the outer perimeter of the set of three polygons, and the proportion of that outer perimeter that corresponds to each of the subpolygons? Thanks in advance

[JoeBorgione]

You have the three original polygons, correct?  You can take the perimeter (length) value of each, and divide them by the perimeter of the large single polygon.  That's the ratio / proportion.  Multiply by 100 to get actual percentage.

[DanPatterson]

The larger polygon of the three polygons.... is it a convex hull you are talking about?

An image of your situation would certainly go a long way to differentiating the contributing segments of the various perimeters for shapes.  Even simple shapes don't yield simple solutions (consider 3 circles enclosed within a circle, and 3 triangles within a triangle