[geos-devel] GEOSConstrainedDelaunayTriangulation

[Martin Davis]

An offshoot of the Ear-Clipping work is going to be a Concave Hull
algorithm for Polygons.  It runs ear-clipping on the outside of the polygon
until some criteria is reached (either a target reduction in number of
vertices or limit to increase in area).  This essentially "shrink-wraps"
the polygon.

Could isochrones be formed by buffering the roads by a small amount and
then constructing the Polygon Concave Hull?

On Thu, Sep 23, 2021 at 2:38 PM Darafei "Komяpa" Praliaskouski <
me at komzpa.net> wrote:

> Hi,
>
> The interesting one is to get a CDT of a collection of linestrings with
> Z(M) for interpolation - mainly for creating isochrones from time annotated
> road maps. This is available in SFCGAL and requires pre-noded input. Can
> this function be adjusted for feature parity with SFCGAL?
>
> Additionally, integrating this into PostGIS it would be nice to get a TIN.
>
> On Fri, Sep 24, 2021 at 12:20 AM Paul Ramsey <pramsey at cleverelephant.ca>
> wrote:
>
>> FYI on a big new port dropping from JTS today. Maybe Martin can share
>> some pictures.
>>
>>   - CAPI: GEOSConstrainedDelaunayTriangulation, builds a constrained
>> triangulation
>>           of an input Polygon or MultiPolygon, returning a
>> GeometryCollection(Polygon)
>>           of the triangles.
>>
>>
>>
>> https://github.com/libgeos/geos/commit/896af228fb27076bdd7f0529d55b3e79e3f10191
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