
<html><head><meta http-equiv="content-type" content="text/html; charset=utf-8"></head><body dir="auto">This should help<div><br></div><div><div style="display: block;" class=""><div style="-webkit-user-select: all; -webkit-user-drag: element; display: inline-block;" class="apple-rich-link" draggable="true" role="link" data-url="https://www.opengis.ch/2022/08/30/writing-a-feature-based-processing-algorithm-at-the-example-of-m-value-interpolation/"><a style="border-radius:10px;font-family:-apple-system, Helvetica, Arial, sans-serif;display:block;-webkit-user-select:none;width:300px;user-select:none;-webkit-user-modify:read-only;user-modify:read-only;overflow:hidden;text-decoration:none;" class="lp-rich-link" rel="nofollow" href="https://www.opengis.ch/2022/08/30/writing-a-feature-based-processing-algorithm-at-the-example-of-m-value-interpolation/" dir="ltr" role="button" draggable="false" width="300"><table style="table-layout:fixed;border-collapse:collapse;width:300px;background-color:#E9E9EB;font-family:-apple-system, Helvetica, Arial, sans-serif;" class="lp-rich-link-emailBaseTable" cellpadding="0" cellspacing="0" border="0" width="300"><tbody><tr><td vertical-align="center"><table bgcolor="#E9E9EB" cellpadding="0" cellspacing="0" width="300" style="font-family:-apple-system, Helvetica, Arial, sans-serif;table-layout:fixed;background-color:rgba(233, 233, 235, 1);" class="lp-rich-link-captionBar"><tbody><tr><td style="padding:8px 0px 8px 0px;" class="lp-rich-link-captionBar-textStackItem"><div style="max-width:100%;margin:0px 16px 0px 16px;overflow:hidden;" class="lp-rich-link-captionBar-textStack"><div style="word-wrap:break-word;font-weight:500;font-size:12px;overflow:hidden;text-overflow:ellipsis;text-align:left;" class="lp-rich-link-captionBar-textStack-topCaption-leading"><a rel="nofollow" href="https://www.opengis.ch/2022/08/30/writing-a-feature-based-processing-algorithm-at-the-example-of-m-value-interpolation/" style="text-decoration: none" draggable="false"><font color="#000000" style="color: rgba(0, 0, 0, 1);">Writing a feature-based processing algorithm at the example of M-value interpolation</font></a></div><div style="word-wrap:break-word;font-weight:400;font-size:11px;overflow:hidden;text-overflow:ellipsis;text-align:left;" class="lp-rich-link-captionBar-textStack-bottomCaption-leading"><a rel="nofollow" href="https://www.opengis.ch/2022/08/30/writing-a-feature-based-processing-algorithm-at-the-example-of-m-value-interpolation/" style="text-decoration: none" draggable="false"><font color="#A2A2A9" style="color: rgba(60, 60, 67, 0.6);">opengis.ch</font></a></div></div></td><td style="padding:6px 12px 6px 0px;" class="lp-rich-link-captionBar-rightIconItem" width="36"><a rel="nofollow" href="https://www.opengis.ch/2022/08/30/writing-a-feature-based-processing-algorithm-at-the-example-of-m-value-interpolation/" draggable="false"><img style="pointer-events:none !important;display:inline-block;width:36px;height:36px;border-radius:3px;" width="36" height="36" draggable="false" class="lp-rich-link-captionBar-rightIcon" alt="cropped-logo-round.png" src="cid:A98E9E1C-F8D9-4476-9CB6-AC28B967AEFB"></a></td></tr></tbody></table></td></tr></tbody></table></a></div></div><br><a href="https://docs.qgis.org/3.22/en/docs/user_manual/expressions/functions_list.html#make-point-m">https://docs.qgis.org/3.22/en/docs/user_manual/expressions/functions_list.html#make-point-m</a></div><div><br></div><div><br></div><div><div style="display: block;" class=""><div style="-webkit-user-select: all; -webkit-user-drag: element; display: inline-block;" class="apple-rich-link" draggable="true" role="link" data-url="https://docs.qgis.org/latest/en/docs/user_manual/expressions/functions_list.html"><a style="border-radius:10px;font-family:-apple-system, Helvetica, Arial, sans-serif;display:block;-webkit-user-select:none;width:300px;user-select:none;-webkit-user-modify:read-only;user-modify:read-only;overflow:hidden;text-decoration:none;" class="lp-rich-link" rel="nofollow" href="https://docs.qgis.org/latest/en/docs/user_manual/expressions/functions_list.html" dir="ltr" role="button" draggable="false" width="300"><table style="table-layout:fixed;border-collapse:collapse;width:300px;background-color:#E9E9EB;font-family:-apple-system, Helvetica, Arial, sans-serif;" class="lp-rich-link-emailBaseTable" cellpadding="0" cellspacing="0" border="0" width="300"><tbody><tr><td vertical-align="center"><table bgcolor="#E9E9EB" cellpadding="0" cellspacing="0" width="300" style="font-family:-apple-system, Helvetica, Arial, sans-serif;table-layout:fixed;background-color:rgba(233, 233, 235, 1);" class="lp-rich-link-captionBar"><tbody><tr><td style="padding:8px 0px 8px 0px;" class="lp-rich-link-captionBar-textStackItem"><div style="max-width:100%;margin:0px 16px 0px 16px;overflow:hidden;" class="lp-rich-link-captionBar-textStack"><div style="word-wrap:break-word;font-weight:500;font-size:12px;overflow:hidden;text-overflow:ellipsis;text-align:left;" class="lp-rich-link-captionBar-textStack-topCaption-leading"><a rel="nofollow" href="https://docs.qgis.org/latest/en/docs/user_manual/expressions/functions_list.html" style="text-decoration: none" draggable="false"><font color="#000000" style="color: rgba(0, 0, 0, 1);">12.2. List of functions — QGIS Documentation documentation</font></a></div><div style="word-wrap:break-word;font-weight:400;font-size:11px;overflow:hidden;text-overflow:ellipsis;text-align:left;" class="lp-rich-link-captionBar-textStack-bottomCaption-leading"><a rel="nofollow" href="https://docs.qgis.org/latest/en/docs/user_manual/expressions/functions_list.html" style="text-decoration: none" draggable="false"><font color="#A2A2A9" style="color: rgba(60, 60, 67, 0.6);">docs.qgis.org</font></a></div></div></td><td style="padding:6px 12px 6px 0px;" class="lp-rich-link-captionBar-rightIconItem" width="36"><a rel="nofollow" href="https://docs.qgis.org/latest/en/docs/user_manual/expressions/functions_list.html" draggable="false"><img style="pointer-events:none !important;display:inline-block;width:36px;height:36px;border-radius:3px;" width="36" height="36" draggable="false" class="lp-rich-link-captionBar-rightIcon" alt="qgis_logo.ico" src="cid:0F973353-710E-42B2-9223-76BF13B7CE3B"></a></td></tr></tbody></table></td></tr></tbody></table></a></div></div><br></div><div><br><div dir="ltr">Envoyé de mon iPad</div><div dir="ltr"><br><blockquote type="cite">Le 10 mars 2023 à 15:25, Stewart Holt via QGIS-User <qgis-user@lists.osgeo.org> a écrit :<br><br></blockquote></div><blockquote type="cite"><div dir="ltr"><div dir="ltr">The need is to put cumulative distance on each point, so P1.M would be zero, P2.M would be the 3D distance from P1 to P2 and P3.M would be the sum of P2.M plus the 3D distance from P2 to P3, etc. The M value of each point would be the cumulative 3D distance from P1.<br><div><br></div><div>Uses of the M value are the ability to click on line and get distance and in producing elevation profiles.</div><div><br></div><div>Stewart</div></div><br><div class="gmail_quote"><div dir="ltr" class="gmail_attr">On Fri, Mar 10, 2023 at 2:44 PM Andrea Giudiceandrea via QGIS-User <<a href="mailto:qgis-user@lists.osgeo.org">qgis-user@lists.osgeo.org</a>> wrote:<br></div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex">Hi Stewart,<br>

it is not clear to me exactly what to want to achieve. If you want to <br>

calculate the 3d length of a 3d line, then you can use the length3d <br>

function <br>

<a href="https://docs.qgis.org/3.22/en/docs/user_manual/expressions/functions_list.html#length3d" rel="noreferrer" target="_blank">https://docs.qgis.org/3.22/en/docs/user_manual/expressions/functions_list.html#length3d</a><br>

<br>

Best regards.<br>

<br>

Andrea Giudiceandrea<br>

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