topic Re: Edit Function to explode multi-part feature in silverlight in ArcGIS API for Silverlight Questions

Edit Function to explode multi-part feature in silverlight

ArtUllman — Fri, 06 Jan 2012 18:14:11 GMT

I need to be able to provide a function for users to explode multi-part polygons in a silverlight application. I am using the Editor class and Geometry services for all of my other functions. I do not see any built-in functions for exploding multi-part features either in the Editor Class, or in the Geometry Service. The only way I can think to do this manually would be to grab the point collections, and check to see if they are clockwise or counter-clockwise so I can tell if the point collections are donuts or multi-part features. Unfortunatelly, I don't see any built-in functions that can tell me the ring orientation. I know that nettopology suites has some libraries, that I could possibly look into.

What is the best way for me to explode a multi-part feature in Silverlight? It sure would be nice if the geometry service or editor class had this functionality built-in.

Re: Edit Function to explode multi-part feature in silverlight

dotMorten_esri — Fri, 06 Jan 2012 18:57:23 GMT

Yes you would have to do this manually so you are on the right track.
For ring orientation a simple method is to look for the top-most point (ie highest Y value) in a ring, and see of the previous point is to the left or right of it. (There's are some edgecases: Directly below=> check previous point. Is first vertex, check last vertex instead of previous).

Re: Edit Function to explode multi-part feature in silverlight

ArtUllman — Fri, 06 Jan 2012 19:40:18 GMT

Thanks. That is a really good idea for checking ring orientation. That should make it real easy. That solves my problem.

By the way, if the ArcGIS Server team ever runs out of things to do, I would not mind having an Explode Multi-Part feature option for the Geometry Service. 😉

Re: Edit Function to explode multi-part feature in silverlight

DeminHu — Fri, 06 Jan 2012 20:16:03 GMT

Hi, Art

when I have many user drawn graphics which I need to use for query or clip, I simplify them first, otherwsie, I get uncorrect results because of drawing directions. I am not for sure this will help you situation.

Good Luck.

Demin