Advanced Modeling and Custom Elements
A model that only extruded flat surfaces isn't modeling the design — it's tracing it. Use these tools for elements that have real three-dimensional character.
Why this matters
Site design includes elements that can't be produced by simple extrusion: landforms that rise and fall in multiple directions, entry structures with tapered profiles, signage with dimensional character, seating elements with ergonomic curves. These require surface and solid modeling tools. Not every project needs all of them, but knowing what's available means you can model what you design rather than simplifying the design to fit what you can model.
Surface creation tools
| Command | What it does | Best used for |
|---|---|---|
| LOFT | Creates a surface between two or more profile curves | Landforms with varying cross-sections; ramps and berms with changing profiles; entry canopies |
| REVOLVE | Creates a 3D object by rotating a profile curve around an axis | Circular fountains, round planters, rotational structures |
| SWEEP1 | Sweeps a profile curve along a single rail path | Handrails, curb transitions, linear elements with consistent cross-section |
| SWEEP2 | Sweeps a profile curve along two rail paths | Tapered elements where both the path and the width change |
| PATCH | Generates a smooth surface from boundary curves or point clouds | Capping openings, filling irregular surface holes, organic landforms |
| BLEND | Creates a smooth transitional surface between two open surface edges | Connecting two surfaces with a smooth tangent transition — entry slopes into flat areas |
| PLANARSRF | Creates a flat surface from a closed planar curve | Flat roofs, overhead shade structures, level paving areas where SPLIT produced an open curve |
Solid operations
| Command | What it does | Notes |
|---|---|---|
| BOOLEANUNION | Combines two overlapping solids into one | Site sculptures, merged structural elements. Both objects must be closed solids. |
| BOOLEANDIFFERENCE | Subtracts one solid from another | Cutting openings in walls, removing material from a form. The subtracted object is consumed in the operation. |
| BOOLEANINTERSECTION | Retains only the overlapping volume of two solids | Finds what two forms share — useful for complex intersecting geometries |
| BOOLEANSPLIT | Splits one solid into separate/intersect parts without consuming either | Non-destructive version — use when you need both the cut and the removed piece |
| SHELL | Hollows a solid with a defined wall thickness | Planters, wall enclosures, any element that should appear hollow rather than solid |
| FILLETEDGE | Rounds selected edges of a solid or polysurface | Curb profiles, furniture edges, any physical edge that has a radius in the real world |
Utility commands for modeling
| Command | What it does |
|---|---|
| TWEENCRV | Creates interpolated curves at set intervals between two curves — useful for grading transitions and organic landforms |
| EXTRACTISOCRV | Pulls a curve from the interior structure of a surface — useful for creating section cuts or manipulating surface shape |
| DUPEDGE / DUPBORDER | Extracts edge curves from a surface or its entire border — the source geometry for new modeling operations |
| REBUILD | Adds control points to a surface for finer shape editing — use sparingly, adds file weight |
| REBUILDMESH | Adds quads to a mesh for more detail — primarily used on the terrain mesh before REDUCEMESH if more definition is needed |
Try this
Model one custom element for your site that cannot be produced by simple extrusion. Entry signage, a site sculpture, a trellis structure, a distinctive seating element — pick something that has dimensional character in the real world and requires at least one of the surface creation tools above. Before modeling it, draw the profile curves it needs. Modeling in Rhino always starts with the curves that define the form.
What breaks
Boolean operations on non-solid objects — Boolean commands require closed polysurfaces (solids). If a Boolean fails, run SELBADOBJECTS and check for naked edges. A single open edge prevents an object from being recognized as a solid. Use SHOWEDGES to highlight naked edges and identify where surfaces aren't joined.
LOFT with misaligned seams — when LOFTing between multiple curves, the seam points must align or the surface will twist. Rhino shows seam indicators during the LOFT command — adjust them to match before accepting the result.