I had a set of Surveyed observations as a JXL file which I imported to TBC.
I created a number of Line strings after sorting the points to various layers.
I tried to change elevation by a Delta Elevation Command by +100m to avoid negative elevation values.
The elevation of the line strings changed. Elevation of Points did not.
I created a Surface by selecting All. The resultant surface was from the points only with Negative Elevation values.
What is wrong?
I attach my file.