Starting data
The starting data is the file 'topo_nlc.dat', that is a text file with xyz of a grid (5800 points)
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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
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Reconstructed NURBS surfaces
- Reconstruct surf-meshes from mesh
Geometry->Create->Surface mesh
The 'surface-mesh' is a kind of GiD's pseudo-surface, that standard curves as boundary, but its inner shape is defined by a triangulation.
The next image show several surface-mesh entities, one of them is showing the inner edges of its underlying mesh.
Reconstructed surface-mesh
This entity is not a CAD standard surface, and can't be exported in exchange formats. Also most geometrical edit GiD tools can not be used with this kind of entity, for example intersection surface-surface, surface-curve, split, etc. are not available. Basically the only available tool is that can be re-meshed.