Setting Data Driven Pages rotation when index has extra page polygons edited into it?

Question

I have created an index to use with data drive pages. I used strip map index and then altered the geometry of the index polygons to better fit my project area. I also added additional index polygons. As a result I copied the geometry of the polygons and created a new index shapefile. In this new shapefile I populated the attribute table with labeling along with before and after label (since some of the maps are sequential for match lines).

I now need to add a field which calculates the data frame rotation for each polygon. Strip Map index does this automatically, but under the circumstances, I need to do this semi manually. How do I populate an attribute field with the data frame rotation angle?

Answer 1

As commented by @FelixIP:

Calculate minimum bounding geometry of modified rectangles. There is an option to calculate bearing

The Minimum Bounding Geometry tool which:

Creates a feature class containing polygons which represent a specified minimum bounding geometry enclosing each input feature or each group of input features.

has a RECTANGLE_BY_WIDTH option that can set:

MBG_Orientation—The orientation of the longer side of the resulting rectangle.

I have not tested it, and was unaware of this tool until I read @FelixIP's comment, but it looks like it will do what you describe, and at all license levels of ArcGIS for Desktop.