<div dir="ltr">Hi Jeroen,<div><br></div><div>I'm not really following what your proposal involves or how it differs from the existing arc/arc intersection code. But if you want to flesh it out in a GitHub issue or pull request, I can take a look at it.</div><div><br></div><div>Dan</div></div><br><div class="gmail_quote gmail_quote_container"><div dir="ltr" class="gmail_attr">On Tue, Sep 15, 2026 at 7:43 PM Jeroen Bloemscheer <<a href="mailto:jeroen.bloemscheer@merkator.com">jeroen.bloemscheer@merkator.com</a>> wrote:<br></div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex">



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<span style="text-transform:none">Hi,</span></div>
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With curve types and CircularArcIntersector now in main, I’d like to propose a small, incremental addition—not an OverlayNG rewrite.</div>
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Proposal: introduce a closed‑form circular arc/arc intersection implemented on an algorithm‑side ExactCircularArc value type in geos::algorithm::exactcurve (not a new geos::geom type). When two circular 3‑control windows properly cross, intersection vertices
 are added on each arc at the intersection points. geom::CircularString remains the WKT/WKB representation; the operation does not take geom::CircularString as input.</div>
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No changes to the C API, ExactCurve, ArcNoder, or SegmentString.</div>
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Out of scope: circular‑arc/chord interior intersections, buffering, overlay operations, and CIRCLE as a separate SQL/MM type.</div>
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Refs: Discussion #1516; historical #1046 and #1382.</div>
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Would opening a GitHub issue for this specific slice be useful, or would you prefer that I keep the work on a fork until there’s a concrete PR? I’ll only open an issue if you consider it helpful.</div>
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Jeroen Bloemscheer</div>
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<span style="text-transform:none">Merkator / OSGeo bloemscheer</span></div>
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<td style="width:43.4228%;vertical-align:middle"><span style="font-family:Tahoma,Geneva,sans-serif"><span style="font-size:20px;color:rgb(40,50,78)"><strong>Jeroen Bloemscheer</strong></span><br>
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