<div dir="ltr">Hi Alexandre<div><br></div><div>What you have to be aware of is the subtle difference between snapping to a vertex and a geometry edge. As I understand the documentation, ST_snap will behave differently when snapping to a ordinary linestring and the same linestring defined with multiple redundant vertices (e.g. LINESTRING(0 0, 0 1, 0 3)). If the polygons in your table are huge and mostly straight, you might get something closer to your intended effect by adding coordinates along the edges of your polygons.</div><div><br></div><div>Åsmund<br><div class="gmail_extra"><br><div class="gmail_quote">On Wed, Sep 24, 2014 at 2:04 PM, Alexandre Neto <span dir="ltr"><<a href="mailto:senhor.neto@gmail.com" target="_blank">senhor.neto@gmail.com</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div dir="ltr">Hi Rémi,<div><div><br></div><div>I'm not sure If I understood your answer correctly. In the documentation of <a href="http://postgis.org/docs/ST_Snap.html" target="_blank">ST_snap()</a> there are some simple examples showing a polygon vertex snapping to a near by linestring (or it's vertex). Shouldn't this be the same case.</div></div><div><br></div><div>The documentation says nothing about the use of geometry collections, maybe that's the problem?</div><div><br></div><div>Thanks,</div><div><br></div><div>Alexandre Neto</div></div><div class="HOEnZb"><div class="h5"><div class="gmail_extra"><br><div class="gmail_quote">On Wed, Sep 24, 2014 at 12:46 PM, Rémi Cura <span dir="ltr"><<a href="mailto:remi.cura@gmail.com" target="_blank">remi.cura@gmail.com</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div dir="ltr"><div><div>Hey, <br>snap is deceiptively named.<br></div>As far as I know It just snaps points to points (or points in geometry to points in geometry).<br></div>For exemple, if you draw 2 square side by side, one being bigger than the other, and separate theim with small distance, snap will do nothing.<br>Cheers,<br>Rémi-C<br></div><div class="gmail_extra"><br><div class="gmail_quote"><div><div>2014-09-24 13:41 GMT+02:00 Alexandre Neto <span dir="ltr"><<a href="mailto:senhor.neto@gmail.com" target="_blank">senhor.neto@gmail.com</a>></span>:<br></div></div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div><div><div dir="ltr">Hello all,<div><br></div><div>I have to tables in postgis. table one has a set of adjacent polygons that covers all my area o interest, while table to have a few polygons across the same area.</div><div><br></div><div>Some boundaries of table 2 should snap to the table 1 polygons, but they don't.</div><div><br></div><div>I'm trying to use st_snap to correct this, but I'm not being able to do it. There are vertices that "refuse" to change while other (just a few do). I'm already using a very big tolerance.</div><div><br></div><div> Therefore I need your help to see if my query looks correct or not.</div><div><br></div><div><br></div><div><div>WITH snap_grid as</div><div>(</div><div>SELECT</div><div> St_Collect(f.geom) as geom</div><div>FROM</div><div> table_1 as f</div><div>)</div><div>SELECT </div><div> r.gid, st_snap(r.geom,q.geom,10) as geom</div><div>FROM </div><div> table2 as r,</div><div> snap_grid as q</div><div>WHERE r.gid = 53</div></div><div><br></div><div>I already tried dumping all point form the table 1 polygons, but the result is "similar".</div><div><br></div><div>Thanks in advance,</div><div><br></div><div>Alexandre Neto</div></div>
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