Writing (SF)CGAL geometry to PostGIS

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Writing (SF)CGAL geometry to PostGIS

Zac Goldstein

I realize this is a mailing list for PostGIS, but I couldn't find support for SFCGAL so I'm hoping someone here has some insight.  I'm trying to write CGAL geometry to postgis, but the loss of precision from exact geometry to double precision is causing my points to no longer be coplanar.  This results in an error when I try to use SFCGAL functions on such geometry in PostGIS.  Is there a common workaround?

In the event that there is no workaround:

For maintainability reasons, I would prefer to not have to edit SFCGAL source directly, but there are a couple solutions on that end that come to mind.   The easiest might be to simply reduce the tolerance variable in the IsPlane3D check.  Does this risk causing other problems for algorithms that expect coplanar points to 1e-9 tolerance though?  

My second idea is to construct the SFCGAL object by projecting the points from the database geometry onto a best-fit plane.  While computationally more intensive, this second approach might be more robust.  

Any thoughts or suggestions for better solutions that don't require editing SFCGAL directly?


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