Exporting transect vertex elevation data

SpaceGIS

Hi!

I need to export the elevation data of both ends of a series of 7m long transects, spaced 1m apart, over a 23km route in order to get a chart of roll angle across the transect. I've generated the transects, but no elevation data is transferred to the attributes when I follow the instructions for "Analysis and Measurement" "Apply elevations to selected features". I have both multi-beam echo sounder data in xyz format and a geotiff of the same data, but neither is referenced when I try this - Any help gratefully received!

SpaceGIS

btw, I can generate a profile across the transect (perpendicular path profile), so I know it can read the data.