self intersecting polygons & simplify geometry service

[JamesCrandall]

I'd like to know how much the simplify task of the geometry service "alters" the input geometry?

We have a public-facing Web AppBuilder application with a custom widget that allows users to upload a shapefile with polygon features of large areas that may be complex (think about a municipality with neighborhoods delineated).  These boundaries get added to a graphics layer when uploaded as a .shp and ultimately offers the user a save button that performs applyEdits on a FeatureService with the features in this graphics layer.  It's actually pretty straight forward and works well.

Problem: cases where users have uploaded shapefiles containing self-intersecting polygon features, which causes the applyEdits to fail.

We could just automatically perform a simplify on the features prior to performing applyEdits.  This allows the geometry to be saved but we're unsure how much the simplify has altered the input features and no way to inform the user "how much" it has changed or a way to quantify that the changes in geometry are acceptable.

I suppose we could just inform the user about this, allow them to exit or continue but we still need a way to get their boundaries into our system.  In these cases we'd just have to do perform the update manually in ArcGIS Desktop.

Comments appreciated!

[RobertScheitlin__GISP · Accepted solution]

James,

   I don't have any reference for this but the simplify task only makes polygons that self intersect into multiple rings that do not. It does not change the overall appearance of the polygon. 

[JamesCrandall]

I see. 

Since we are actually running a union on the input features to create a single feature for the applyEdits, we'd actually solve the issue by simply automatically running the simplify operation.

This is promising.

Thanks for the input!