Starting data

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.

How to create a surface model?

The model has only points, not surfaces. There are different ways to create surfaces

Connect with '2D Delaunay triangulation'

It could be done selecting a checkbox when importing or after with process commands (Mescape Meshing ConnectPoints CreateSurfaces)

Create a single smooth NURBS surface approximating the cloud of points

Geometry->Create->NURBS surface->By points