I have a small circle in SDE which I'm trying to extract through ArcObjects into well-known-binary (for later import into other systems).

Using the IWkb interface I can obtain the WKB, but it comes out as a PolyLine with 2 points - both exactly the same. I've hand parsed the WKB to confirm this is what ArcObjects is returning.

Are there any ways to get ArcObjects to export circles as WKB and maintain the circle? e.g. as a CircularString or similar.

I'm using ArcObjects 9.3.

  • Hmm.. considering the comments to @JasonScheirer's answer, since you know the circular traits--in this case the "endpoint" and diameter details--would it be acceptable workaround to write your own method to return the circle WKB?
    – elrobis
    Apr 12, 2016 at 16:31

1 Answer 1


Circles may be represented as curves internally, which WKB doesn't do. You probably need to Densify it first.

  • 2
    WKB does have support for curves, perhaps it was added in a later version. I can't find the actual spec, but wikipedia lists geometry types for circles and curves, and it appears SQL Server 2012 at least supports these (I haven't checked anything else). Oct 12, 2012 at 1:40
  • WKB does support curves--it's the GeometryEnvironment WKB methods that don't support curves. Apr 14, 2014 at 16:59

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