Hi everyone, 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. 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 several methods, including adding a field to the attribute table of the polyline shapefile and using "Calculate Geometry" to calculate "3D Length", using the "Add Surface Geometry" tool (3D Analyst -> Functional Surface), and using the "Add Z Information" tool (3D Analyst -> 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. Does anyone have any insight on what could be going wrong? Thanks!
... View more
