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# How to calculate intermediate polygon between two polygons using ArcGIS

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05-31-2018 08:39 AM
New Contributor II
I have a two polygons, the big one and the small one inside of the big one. Now I want to create the new polygon which is on the average middle between these two (big and small). I have used Erase tool to create just one donate polygon (without the small one in the middle) and to create negative buffer, but that is not a good idea. New polygon should have some mix of geometries between small and big one.
NOTE that these two polygons doesn't have the same geometry.
All of these I want to finish using ArcGIS.
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1 Solution

Accepted Solutions
MVP Alum

Just a quick workflow idea that could be tried if you have access to Spatial Analyst or 3D Analyst.  Untested, but I think this could work.  It would need to be fleshed out with the specific processes (this is just the basic process).

1. Convert the polygons to lines
2. Combine into one feature class (if not already)
3. Add an integer field called "Elevation"
4. Populate one line with zero and the other with 100
5. Convert the lines to a surface (raster)
6. Contour the surface, specifying an elevation of 50.  This will essentially produce the result you are seeking.
7. Convert to vector, then Convert the lines back to polygons.

Chris Donohue, GISP

5 Replies
Deactivated User

Not clear... you say you want to do this in QGIS ...

perhaps try their discussion group  https://gis.stackexchange.com/

New Contributor II

Sorry, I have edited question now.

MVP Alum

Just a quick workflow idea that could be tried if you have access to Spatial Analyst or 3D Analyst.  Untested, but I think this could work.  It would need to be fleshed out with the specific processes (this is just the basic process).

1. Convert the polygons to lines
2. Combine into one feature class (if not already)
3. Add an integer field called "Elevation"
4. Populate one line with zero and the other with 100
5. Convert the lines to a surface (raster)
6. Contour the surface, specifying an elevation of 50.  This will essentially produce the result you are seeking.
7. Convert to vector, then Convert the lines back to polygons.

Chris Donohue, GISP

New Contributor II

Fantastic idea! Could you tell me which tools are the best to use to create the surface and which one to create 50m elevation Contour?

by
Occasional Contributor

Just edit the polygon using Edit Toolbar, select the smaller/inner polygon.  Once selected under Editor Toolbar select CLIP.  You have a choice to Preserve or Discard the area of intersection.   Discard it and calculate the area  Easy Peazy