<div dir="ltr">You're right, I didn't describe that well. I should say instead that these functions aren't using GEOS' behavior of cleaning up topological collapses (GEOS_PREC_NO_TOPO and GEOS_PREC_KEEP_COLLAPSED in the CAPI). GEOS is indeed doing a pointwise precision reduction, which should be a no-op in my use case but may not be in others.<div><br></div><div>Dan</div></div><div class="gmail_extra"><br><div class="gmail_quote">On Thu, Mar 10, 2016 at 4:53 AM, Sandro Santilli <span dir="ltr"><<a href="mailto:strk@keybit.net" target="_blank">strk@keybit.net</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><span class="">On Wed, Mar 09, 2016 at 07:20:57PM -0500, Daniel Baston wrote:<br>
<br>
> Branch is at <a href="https://github.com/postgis/postgis/pull/100" rel="noreferrer" target="_blank">https://github.com/postgis/postgis/pull/100</a><br>
<br>
> * GEOS provides the ability to reduce a geometry's precision, cleaning up<br>
> topological collapses that may result from coordinate movement. These<br>
> functions don't take advantage of this behavior; they assume that the user<br>
> is providing geometry whose coordinates are in fact precise at the level<br>
> specified. I do think there should be a separate ST_ReducePrecision to<br>
> allow a user to take advantage of this feature.<br>
<br>
</span>As far as I know the only way to request use of fixed-precision<br>
through the GEOS C-API is by invoking the function that does<br>
encode the precision into the GEOS version of the geometry and at<br>
the same time rounds its coordinates to it, so there should be<br>
no way to report a precision assumption to GEOS (as of GEOS<br>
trunk C-API).<br>
<br>
How else did you implement the precision support, if not using<br>
those functions (GEOSGeom_setPrecision_r) ?<br>
<br>
--strk;<br>
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