I calculated a trail up mountain using least cost path analysis. I converted the raster trail to a polyline using the raster to polyline. I then used the feature vertices to points (input being the polyline), and i then used the extract multivalues to points where my 2 rasters were slope and elevation for the trail points. SO what I have now is a points layer with unique ids that have slope and elevation data for each record. I can drape the points layer over my elevation DEM in ArcScene but I want to be able display the trail with a polyline over the DEM. I know you can convert points to line but the output is just one id for the line so I cannot accurately display the trail in a line.
The help file for the feature vertices to points tool states that all original fields are kept. If the unique ID in your polyline happens to be the FID or OBJECTID then that will be lost.
So a simple solution is to add a new field call it "PID" for polyline ID and copy over the FID/OBJECTID in your polyline dataset before you explode it into the individual vertices. That field will still be there when you convert points to line and you can set the LINE_FIELD parameter to PID.