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<div dir="ltr" data-setdir="false">Hi Klaus and Patrick, <br></div><div dir="ltr" data-setdir="false"><br></div><div dir="ltr" data-setdir="false">With respect to 'Snap to grid', I would like to chime in that the grid is usually meant to be quite fine. For example, on a scale smaller than meter or a foot. In the case of the 'Simplify' tool, set to 'Snap to grid', this is controlled by the 'Tolerance', you will note that the units change according to the CRS units of the selected layer. It is frequently used to snap points and lines together for use with networks. Because, while your line file may look like the nodes are all connected to each other, in actuality they may be off by a few milli-, micro- or nanometers so the routing tool will see this as the two lines not being connected. You can increase the Tolerance upwards and give your vector a pixelated look to it.<br></div><div dir="ltr" data-setdir="false"><br></div><div dir="ltr" data-setdir="false">Just a guess, I would presume the layer's bounding box is used to set the grid. If that is not enough of an explanation please do look up the code references given by Andrea (I have left them inline below). <br></div><div dir="ltr" data-setdir="false"><br></div><div dir="ltr" data-setdir="false">-Thayer<br></div><div dir="ltr" data-setdir="false"><br></div><div><br></div>
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On Wednesday, June 29, 2022 at 08:29:23 AM EDT, qgis-user-request@lists.osgeo.org <qgis-user-request@lists.osgeo.org> wrote:
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<div>> Regards.<br><div dir="ltr">> Andrea Giudiceandrea<br></div><div dir="ltr">> <br></div><div dir="ltr">> [1] <br></div><div dir="ltr">> <a href="https://api.qgis.org/api/3.22/classQgsMapToPixelSimplifier.html#a0b97d82a3abd0876ce529ba9d9cfd412" rel="nofollow" target="_blank">https://api.qgis.org/api/3.22/classQgsMapToPixelSimplifier.html#a0b97d82a3abd0876ce529ba9d9cfd412</a><br></div><div dir="ltr">> [2] <br></div><div dir="ltr">> <a href="https://github.com/qgis/QGIS/blob/e113457133fe5d7c3f5e3b90a2795b8b691ae269/src/core/qgsmaptopixelgeometrysimplifier.cpp#L183-L229" rel="nofollow" target="_blank">https://github.com/qgis/QGIS/blob/e113457133fe5d7c3f5e3b90a2795b8b691ae269/src/core/qgsmaptopixelgeometrysimplifier.cpp#L183-L229</a><br></div><div dir="ltr">> [3] <br></div><div dir="ltr">> <a href="https://docs.qgis.org/3.22/en/docs/user_manual/processing_algs/qgis/vectorgeometry.html?highlight=simplify#snap-points-to-grid " rel="nofollow" target="_blank">https://docs.qgis.org/3.22/en/docs/user_manual/processing_algs/qgis/vectorgeometry.html?highlight=simplify#snap-points-to-grid </a><br></div>> <br><div dir="ltr">> ------------------------------<br></div>> Date: Wed, 29 Jun 2022 11:57:47 +1200<br><div dir="ltr">> From: Patrick Dunford <<a href="mailto:enzedrailmaps@gmail.com" rel="nofollow" target="_blank">enzedrailmaps@gmail.com</a>><br></div><div dir="ltr">> To: <a href="mailto:qgis-user@lists.osgeo.org" rel="nofollow" target="_blank">qgis-user@lists.osgeo.org</a><br></div><div dir="ltr">> Subject: Re: [Qgis-user] Simplify geometry - snap to grid<br></div><div dir="ltr">> Message-ID: <<a href="mailto:62ff8391-0f43-92ae-5c11-c324f2bafb8e@gmail.com" rel="nofollow" target="_blank">62ff8391-0f43-92ae-5c11-c324f2bafb8e@gmail.com</a>><br></div><div dir="ltr">> Content-Type: text/plain; charset=UTF-8; format=flowed<br></div><div dir="ltr">><br></div><div dir="ltr">> Is this the grid you see in View -> Decorations -> Grid ?<br></div><div dir="ltr">><br></div><div dir="ltr">> On 29/06/22 07:50, Delaz J via Qgis-user wrote:<br></div><div dir="ltr">> Hi Klaus,<br></div><div dir="ltr">><br></div><div dir="ltr">> Just a guess: the only snap to grid thing I know about is <br></div><div dir="ltr">> <a href="https://docs.qgis.org/3.22/en/docs/user_manual/working_with_vector/editing_geometry_attributes.html#snapping-on-custom-grid. " rel="nofollow" target="_blank">https://docs.qgis.org/3.22/en/docs/user_manual/working_with_vector/editing_geometry_attributes.html#snapping-on-custom-grid. </a><br></div><div dir="ltr">> Worth a check?<br></div><div dir="ltr">><br></div><div dir="ltr">> Regards,<br></div><div dir="ltr">><br></div><div dir="ltr">> Harrissou<br></div><div dir="ltr">><br></div><div dir="ltr">> Le 28/06/2022 ? 15:54, Klaus Mith?fer via Qgis-user a ?crit?:<br></div><div dir="ltr">>> hello,<br></div><div dir="ltr">>><br></div><div dir="ltr">>> with the simplify tool in QGIS you can simplify geometries using <br></div><div dir="ltr">>> either ?Douglas-Peucker Algorithm, Visvalingam-Algorithm or snap to <br></div><div dir="ltr">>> grid. I understand the algorithms, but how the grid snapping work? <br></div><div dir="ltr">>> Where is is the grid defined? I don't get that point. maybe someone <br></div><div dir="ltr">>> can explain.<br></div><div dir="ltr">>><br></div><div dir="ltr">>> Thanks an kind regards<br></div><div dir="ltr">>> Klaus<br></div><br></div>
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