https://community.esri.com/t5/3d-questions/calculate-3d-surface-length-from-a-dem/m-p/1322424#M4901 <P>Trying to calculate the 3D surface length of a polyline on a DEM.&nbsp;</P><P>Using the Add surface information &amp; interpolate shape tools both work but return almost identical number if not the same value. Over a 50km DEM with changing elevation it should be more than the 2D length. See attached image. Both 2D shape length and 3D Shape Length identical at 45.031Km</P><P>Seen a similar post on here but no solution as to why the value returns the same.&nbsp;<span class="lia-inline-image-display-wrapper lia-image-align-inline" image-alt="ESRI 3D.PNG" style="width: 400px;"><img src="https://community.esri.com/t5/image/serverpage/image-id/79121iDAE7D03FCAFCD3FB/image-size/medium?v=v2&amp;px=400" role="button" title="ESRI 3D.PNG" alt="ESRI 3D.PNG" /></span></P> Fri, 25 Aug 2023 08:01:57 GMT GraemeArmour 2023-08-25T08:01:57Z https://community.esri.com/t5/3d-questions/calculate-3d-surface-length-from-a-dem/m-p/1322424#M4901 <P>Trying to calculate the 3D surface length of a polyline on a DEM.&nbsp;</P><P>Using the Add surface information &amp; interpolate shape tools both work but return almost identical number if not the same value. Over a 50km DEM with changing elevation it should be more than the 2D length. See attached image. Both 2D shape length and 3D Shape Length identical at 45.031Km</P><P>Seen a similar post on here but no solution as to why the value returns the same.&nbsp;<span class="lia-inline-image-display-wrapper lia-image-align-inline" image-alt="ESRI 3D.PNG" style="width: 400px;"><img src="https://community.esri.com/t5/image/serverpage/image-id/79121iDAE7D03FCAFCD3FB/image-size/medium?v=v2&amp;px=400" role="button" title="ESRI 3D.PNG" alt="ESRI 3D.PNG" /></span></P> Fri, 25 Aug 2023 08:01:57 GMT https://community.esri.com/t5/3d-questions/calculate-3d-surface-length-from-a-dem/m-p/1322424#M4901 GraemeArmour 2023-08-25T08:01:57Z