Create polygon within polygon in same layer

Question

Need help doing this common editing process.  Can't find anything in ArcGis Desktop help files or search of this forum on this.  Can anyone help me?

RichardFairhurst · Answer

Thanks for the response.  I am dealing with creating a new polygon within an existing one in the same feature layer. I followed your last paragraph and that does create the polygons but my problem has been getting the new acres to be correct.  At first, when the new feature is completed, the attribute table will have the same acres for both polygons,  In the past, the original larger polygon acreage has not been reduced in the amount of the new included polygon.  Today in trying this, it seemed to work when I kept the edit session open and had both polygon rows selected and then "calculated geometry" and the correct acres appeared.  So, hopefully, I'm in   business!

Shapefiles do not update the fields related to geometry automatically and you have to manually update them with the Geometry Calculator.  Geodatabase polygon feature classes automatically update their system controlled area and perimeter field values as the polygon geometry changes are committed when you finish a sketch.  I rarely ever use shapefiles, and always convert to a file geodatabase if I have to use data for more than quick and dirty work.

WayneMillen · Answer

Thanks for the response.  I am dealing with creating a new polygon within an existing one in the same feature layer. I followed your last paragraph and that does create the polygons but my problem has been getting the new acres to be correct.  At first, when the new feature is completed, the attribute table will have the same acres for both polygons,  In the past, the original larger polygon acreage has not been reduced in the amount of the new included polygon.  Today in trying this, it seemed to work when I kept the edit session open and had both polygon rows selected and then "calculated geometry" and the correct acres appeared.  So, hopefully, I'm in   business!

RichardFairhurst · Answer

Need help doing this common editing process.  Can't find anything in ArcGis Desktop help files or search of this forum on this.  Can anyone help me?

Start editing a polygon and right click for the context menu.  Click Finish Part and then start drawing inside to create a hole.  See the first item in this list of editing technique to deal with multipart polygons.

A new separate polygon feature would have to be created rather than a multipart polygon to overlap an existing polygon without creating a hole.  The multipart polygon help says:

"Keep in mind that parts in a multipart polygon are spatially separated. They can touch each other at vertices, but they cannot share edges or overlap. When you are sketching a multipart polygon, any parts that share an edge will be merged into a single part when you finish the sketch. In addition, any overlap among parts will be removed, leaving a hole in the polygon."

To create a totally new polygon on top of another, just use the Create Feature menu and click polygon and start drawing a polygon on top of the other polygon.  The original polygon and the new polygon will make up separate feature rows in the attribute table.