<div dir="ltr"><div dir="ltr"><div dir="ltr">Hi Dave,<div><br></div><div>There was a blog post I wrote long time ago, but after some improvements to the pgr_pointsAsPolygon function, when it supported a custom value for "alpha":</div><div><a href="https://georepublic.info/en/blog/2017/catchment-area-calculation-with-pgrouting/">https://georepublic.info/en/blog/2017/catchment-area-calculation-with-pgrouting/</a><br></div><div><br></div><div>I don't remember details anymore, just that I wrote that post and the result was quite OK.</div><div>It seems I got more detailed boundaries, when the alpha value was pretty small like "0.00001".</div><div>Have you tried such a small number?</div><div><br></div><div>Best regards,</div><div>Daniel</div><div><br></div><div><br></div></div></div></div><br><div class="gmail_quote"><div dir="ltr">On Wed, Oct 10, 2018 at 1:43 AM Dave Potts <<a href="mailto:mrdapotts@gmail.com">mrdapotts@gmail.com</a>> wrote:<br></div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div dir="ltr"><div dir="ltr"><div dir="ltr"><div dir="ltr"><div dir="ltr">I have a collection of x,y points and I am trying to draw a bounding polygon. I was unhappy with the default returned, so I decided to a play with the alpha parameter.<br><br>I get no result and the value 'NOTICE: n = 1'<br><br>printed on the console, <br>My sql is <br><br>pgr_pointsAsPolygon('select id,st_x(st_startpoint(the_geom)) as x, st_y(st_startpoint(the_geom)) as y from tmp where label=27,5.0);<br> select pgr_version() returns psql (10.5 (Ubuntu 10.5-1.pgdg16.04+1))<br>The machine is running postgres 10.5-1<br><br>Is there anything wrong with what I am doing? Using an alpha value of 0 does not generate an error.<br><br>regards<br><br><br>Dave.</div><div><br><br><br><br></div></div></div></div></div>
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