How to model organic shapes and topography?

Organic shapes and terrain can't be built from boxes and extrusions. Start from a few good curves, a soft control cage or contour lines, and let the software fill in the surface.

Surfaces from Curves

Most smooth forms start as a few curves — sections, profiles or edges — that a surface is stretched across. Fewer, cleaner curves give smoother surfaces than many messy ones.

You may notice:

Your loft twists or folds in on itself
The surface looks lumpy between the curves

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Tutorial

SubD: Sculpt with a Cage

SubD lets you push and pull a coarse cage while the surface stays smooth — closer to shaping clay than drawing. Explore the form, then convert it to NURBS for precise work; Blender does the same with meshes (Subdivision Surface).

You may notice:

A free form takes hours of patching surfaces together
Your form shows creases where separate pieces meet

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Tutorial

Shaping Terrain

Design your own landform by pulling the points of a flat SubD or surface up and down, or build terrain from contour lines and survey points (Patch, triangle mesh). Revit (Toposolid) and ArchiCAD (Mesh tool) also build terrain from points.

You may notice:

The terrain surface has spikes or holes
Your building floats above or sinks into the ground

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Tutorial

Smooth vs. Stepped Terrain

Pick the terrain form by the output: a smooth surface or mesh for renders and sections, stepped layers for a physical site model. Slice the terrain into layers that match your board thickness (Contour).

You may notice:

The layers of your site model don't match the board thickness
Your smooth terrain can't be laser cut

Search for

C(concept)Topographic model(search Google, opens in a new tab)
L(logic)Contour interval(search Google, opens in a new tab)
T(tool)Contour (Rhino)(search Google, opens in a new tab)

Tutorial

How to make a Contour Terrain Model in RhinoRhinoYouTube(opens in a new tab)