I am new to Therion, so please forgive me if I am making a simple error. I am experiencing a problem when exporting 3d .dxf model data (to AutoCAD) Background : I have a centreline of diving data with LRUD's. Approx 1000m / 0-70m depth / 125stations. Simple linear passage (The St Georges Resurgence, Montvalent, France) I have used the .xvi export of plan and elevation into the map editor. I have drawn 12 plan scraps and 12 elevation scraps. These are joined and have exported correctly as conventional pdf plan and elevation maps. Problem: When I export the data as a dxf model using the '-wall-source maps' option, there appear to be vertical steps in the passage floor and ceiling at the start and end of each (plan) scrap. Within a single scrap there are no steps. Typically the dimensions relative to the centreline in the scrap 'before' the join are correct. The first up/down dimensions in the 'next' scrap are incorrect. The horizontal alignment of the walls is perfect. Typical image illustrating the problem here : http://www.steveclark.demon.co.uk/dxf_error.png It does not appear to be a problem with the centreline data, because if I re-draw two scraps as a single scrap with only 2 wall lines there is no step in the ceiling or floor. There is no step in the pdf elevation export of the same scraps. Joining all the individual wall lines in both plan and elevation does not solve the problem. The export does not appear to use the elevation scraps to generate passage heights. I get identical output if these are deleted or adjusted. If I use the export '-wall-source centreline' option, there are no steps. This, however, does not allow me to export/render any features not recorded in the simple LRUD data. I am relucant to draw the whole survey as a single scrap with just 2 walls, but it appears this may solve the problem. Any thoughts, or is this just a quirk of the dxf export? Regards, Steve Clark