topic Re: Trying to find the 3D (or surface) length along a line - getting weird results? in 3D Questions https://community.esri.com/t5/3d-questions/trying-to-find-the-3d-or-surface-length-along-a/m-p/1104907#M4674 <P>Hello <span class="lia-unicode-emoji" title=":slightly_smiling_face:">🙂</span> Did you ever get any insight into this? The same thing is happening to me: my 3D lengths are shorter than my 2D ones...</P> Tue, 05 Oct 2021 17:27:33 GMT SuzanneFordyce 2021-10-05T17:27:33Z Trying to find the 3D (or surface) length along a line - getting weird results? https://community.esri.com/t5/3d-questions/trying-to-find-the-3d-or-surface-length-along-a/m-p/222606#M1358 <HTML><HEAD></HEAD><BODY><P>Hi everyone,</P><P></P><P>I am trying to construct elevation profiles and then determine the horizontal length (i.e. not taking the elevation into account) and 3D length (i.e. taking the elevation into account) along the profiles. I have been constructing the profiles by digitizing polylines and then using the "Interpolate Shape" tool (under 3D Analyst) to add Z values to the polylines, based on a raster which contains the elevation data. This step of the process has been working properly.</P><P></P><P>I then calculated the horizontal length of each profile by adding a field to the attribute table of the polyline shapefile and using "Calculate Geometry" to calculate "Length". I now need to find the 3D or surface length along each profile. I have tried&nbsp;several methods, including adding a field to the attribute table of the polyline shapefile and using "Calculate Geometry" to calculate&nbsp;"3D Length", using the "Add Surface Geometry" tool (3D Analyst -&gt; Functional Surface), and using the "Add Z Information" tool (3D Analyst -&gt; 3D Features). All three methods return the same results, but they do not make any sense. Many 3D length values are actually lower than the horizontal length values for the same profile - how could this be possible? A line with any kind of elevation change should always have a longer 3D length than horizontal length. For other profiles, the 3D lengths and horizontal lengths are the same, and for many others the 3D length is only slightly higher (by a few metres) than the horizontal length, even when the elevation profile shows relief of hundreds of metres.</P><P></P><P>Does anyone have any insight on what could be going wrong? Thanks!</P></BODY></HTML> Tue, 11 Jun 2019 17:13:01 GMT https://community.esri.com/t5/3d-questions/trying-to-find-the-3d-or-surface-length-along-a/m-p/222606#M1358 ErinBethell 2019-06-11T17:13:01Z Re: Trying to find the 3D (or surface) length along a line - getting weird results? https://community.esri.com/t5/3d-questions/trying-to-find-the-3d-or-surface-length-along-a/m-p/1104907#M4674 <P>Hello <span class="lia-unicode-emoji" title=":slightly_smiling_face:">🙂</span> Did you ever get any insight into this? The same thing is happening to me: my 3D lengths are shorter than my 2D ones...</P> Tue, 05 Oct 2021 17:27:33 GMT https://community.esri.com/t5/3d-questions/trying-to-find-the-3d-or-surface-length-along-a/m-p/1104907#M4674 SuzanneFordyce 2021-10-05T17:27:33Z Re: Trying to find the 3D (or surface) length along a line - getting weird results? https://community.esri.com/t5/3d-questions/trying-to-find-the-3d-or-surface-length-along-a/m-p/1322420#M4900 <P>Did you get a reply on this also having the same issue. Both tools add surface and interpolate shape return almost identical if not same value over a 50km DEM with changing elevation to the 2D</P> Fri, 25 Aug 2023 07:44:56 GMT https://community.esri.com/t5/3d-questions/trying-to-find-the-3d-or-surface-length-along-a/m-p/1322420#M4900 GraemeArmour 2023-08-25T07:44:56Z