Re: [Therion] LOX: Measure distance from station to surface

enable surface in aven? If i try to enable the surface legs, aven prompts me to open some file...

I assume you are trying to "file - open terrain" rather than "view - surface survey legs". Terrain is a different thing, which I have never used, and I don't think you can select parts of it for use with measuring. I think though that Survex's terrain is similar to the type of terrain used by Therion though.