I am using ArcGIS 10.2 and when I run topology on my feature class (which is in NAD 83 Lambert_Conformal_Conic) there were no overlaps. Once I project it into any projection I get overlapping polygons only where there are circles drawn with the circle tool.

This data will be provided to many customers that may choose any projection. The only way I have found to solve the problem is to go back and manually draw the circle instead of using the circle polygon tool. I know some quick tools to get rid of sliver overlaps, but I can't give this data to customers when they may choose many different types of projections. Is there another method to fix this problem?

  • 1
    What software + version? My guess is ArcGIS Desktop, feature class (not shapefile). Could you please confirm that by editing the question and including that information?
    – mkennedy
    Commented Mar 29, 2016 at 22:21

1 Answer 1


I believe the circle tool is creating circular arcs. That is, the circles are defined mathematically rather than geometrically through a series of vertices. When you redraw the circle manually, you're creating a geometric approximation of the circle.

When circular arcs (plus Bezier curves and elliptic arcs) are reprojected the defining points are projected but the shape of the feature is preserved as a the same type. So a circle formed from circular arcs will remain a circle in the new coordinate reference system.

In this case, the circular arc was created in a conformal (shape-preserving) projection. Converted to a new conformal projection but one that has different parameters may cause the circle size to increase or decrease. Converted to an equal area projection like Albers, can cause an odd result because the shape will still be preserved but the area also may change.

If customers are generally going to use coordinate systems that are designed for large-scale data like State Plane zones, the differences should be small. But as you're seeing, can still cause overlaps or gaps.

You may need to densify the polygons to convert them to a geometric representations.

  • Yes, out of approx 65,000 polys there were over 3,000 overlaps for an Albers projection. Only a couple errors when projected in UTMs. The customers will likely be using State Plane as you stated. I will play around with densify tool.
    – Chris
    Commented Mar 29, 2016 at 23:32

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