The starting data is the file 'topo_nlc.dat', that is a text file with xyz of a grid (5800 points)
-9400 -2884100 1557.5228971414 -9201.7543859649 -2884100 1558.9433292625 ... 1900 -2864400 1564.971922013
Files->Import->XZY points...
It is a flat topography, for tutorial purposes will scale z by 50 with Utilities->Move... tool
Note: the move tool could be used also to scale a model if it is represented in unwanted units (e.g. from inches to meters), and to translate the model near the (0,0,0) coordinates origin.
A common graphical problems is that topographic models are mapped from the curved earth to a planar representation with UTM projection and this could become in too big x,y 2D coordinates (model box far from the origin). This is a graphic problem drawing with OpenGL that uses float real numbers for coordinates (about 7-8 significant digits). Staircase graphical artifacts, and the selection in screen could become a little displaced of the entity drawn. An easy solution is to translate the model in XY near the origin.