TOPOSHAPER EXCELLENT SKETCHUP PLUGIN

This is an excellent plugin, TopoShaper by Fredo6, generates Terrains from iso-contours, that is, contours which have a constant or quasi-constant altitude. Often, when generating terrain with the Sandbox > From contours tool, it has smaller of bigger faults, the generated terrain is not even and smooth and can look (let's face it) "ugly". TopoShaper generates beautifully even terrains based on quads which will look excellent in any application you may wish to render them.

TopoShaper generates Terrains:

from a group of iso-contours, that is, contours which have a constant or quasi-constant altitude. The Terrain is generated as a QuadMesh
from a Cloud of Points (given as a group of Guide points). The Terrain is generated as an adaptive Triangular mesh.

TopoShaper: IsoContours works in 4 steps:

Selection of Contours , usually by pre-selecting a group containing the contours before launching TopoShaper
Cleansing Contours, which can be useful when contours are imported as DXF/DWG files. In version 1.0, the Cleansing covers the exclusion / inclusion of contours, their simplification, automatic and manual junctions and removal of small hooks. There is an Altitude Editor to set or modify the altitude of the indivdual contours.
Calculation of Terrain and Preview. The Terrain is computed on a rectangular grid. You can change the grid resolution and have option to configure the hilltops and basins.
Generation of the Terrain Surface as a quad-mesh surface enclosed in a group. Optionally you can include the Skirt and the contour map, with or without altitude labels.

TopoShaper: PointsCloud

TopoShaper::PointsCloud takes a group of Guide Points. If it encloses faces, they will form the Clipping Contours. Otherwise, the default Clipping contours are taken as the convex hull of the points.
The Terrain is generated as an adaptive triangular mesh, where triangles are more dense where the altitude changes. The algorithm is iterative, by refinement of the triangulation until the Terrain is 'smooth' enough (specified by a smoothing angle). Points are part of the mesh (i.e. the terrain passes thorugh the original points).

Here an good videotutorial by Tutorial UP on How To Use TopoShaper Plugin in Sketchup