MoleHill

MoleHill is a Rhino 8 terrain modeling toolkit centered on a document-backed Rhino plugin, with optional Grasshopper components for procedural workflows.

It uses Triangle.NET for constrained Delaunay triangulation and targets .NET 7-based Rhino 8 plugins.

Status: 1.2.1. Install it from Rhino's Package Manager; see CHANGELOG.md for what changed. Bug reports with a repro case are very welcome: see CONTRIBUTING.md. MoleHill is free, and because its triangulator derives from Triangle it may not be sold or bundled in a commercial product; see License.

Release Scope

• MoleHill.Rhino.rhp is the primary release artifact.
• MoleHill.gha is an optional companion plugin for Grasshopper users who want the same terrain operations in a graph workflow.

Rhino Plugin

The Rhino plugin provides the panel-driven workflow for creating, editing, analyzing, and converting managed terrain definitions inside a Rhino document.

Commands

Command	Description
mhPanel	Open the MoleHill panel
mhCreateTerrain	Create a terrain from the current selection and open the panel
mhConvertToRhino	Convert the selected managed terrain into standard Rhino objects
mhValidateTerrainInputs	Clean selected terrain points and curves, including duplicate joined segments
mhSplitAtIntersections	Split selected curves at their pairwise intersections
mhDrapeCurve	Sample selected curves onto a selected mesh or surface along World Z
mhSuggestRoute	Suggest up to three distinct routes between picked points (start, waypoints, end) over a terrain, trading off distance, steepness and earthworks within a hard max grade. Corners are rounded to a MinRadius (0 keeps sharp corners). Previewed in colour; keep all or one as ordinary curves whose profile already obeys the grade, on the current or a chosen Layer, ready to edit and assign to a Grade Path. Each curve carries its length, grades and cut/fill
mhInspectCurve	Open the read-only plan-station profile inspector: an elevation profile coloured by grade, elevation, cut/fill or plan radius, with checks (grade, radius, vertical break, terrain coverage), measurements and an event list; the same colour ramp drives a live viewport overlay, and hovering the profile scrubs a marker along the curve. Label drops elevation / grade / station / cut-fill text dots along the curve
mhSlopeCurveSection	Set or interpolate grade over a selected curve section, including blending to active terrain. Previewed live; Anchor picks which end holds its elevation, and Transition eases the moved end back into the rest of the curve instead of stepping. Reports how far the result strays from the prescribed grade when control-point editing cannot express it exactly
mhCreateWall	Draw a wall rail and generate its parallel, vertically offset companion rail

Grasshopper Components

Terrain exchange

Component	Description
MoleHill Terrain Snapshot	Read the latest completed final terrain, breaklines, and zones from the MoleHill Rhino panel
Construct Terrain	Package an ordinary mesh, breaklines, and a zone tree as open MoleHill Terrain data
Deconstruct Terrain	Expose MoleHill Terrain as ordinary Grasshopper mesh, curves, zone branches, and metadata
Partition Terrain	Insert zone boundaries once and output separate terrain meshes with exact shared seam vertices
Prepare Toposolid	Validate profiles and emit a point-budgeted, error-measured, fingerprinted Revit-neutral terrain package

MoleHill Terrain is deliberately not a closed editing system. Deconstruct it, edit or join the ordinary Rhino geometry with standard Grasshopper tools, then construct it again. Zone branches are region data only; Partition Terrain is the explicit operation that turns them into separate terrain pieces. Terrain Snapshot requires the MoleHill Rhino plugin from the combined package and rejects preview/deferred builds so downstream geometry never silently changes from approximate to final. Prepare Toposolid leaves coordinates in the incoming Rhino model space, retains explicit unit metadata, and performs adaptive point reduction in compiled Core code. Inside Rhino.Inside.Revit (Revit 2025+), a MoleHill > Revit tab adds Write Toposolids (create/update Toposolids and their subdivisions from the Prepare Toposolid package, matched by stable key) and Inspect Toposolids. They ship in the same package as MoleHill.Revit.gha and stay hidden in plain Rhino; Revit's API is never copied into the package. The Revit step is not yet verified in a Revit host.

Surface

Component	Description
TIN Surface	Generate a TIN mesh from points and breaklines
Remesh	Refine a TIN mesh with quality constraints and max edge length
Mesh Smooth	Apply Laplacian Z-smoothing within boundary curves

Grading

Component	Description
Grade Pad	Flatten terrain at pad elevations with slope transitions and cut/fill reporting
Grade Path	Grade roads and paths from centerline elevations, with constant fallback width or automatically matched variable-width edge curves
Retaining Wall	Pair open wall rails, generate wall solids, and grade terrain between toe and top rails
In Situ Stair	Generate stair geometry and terrain transitions from stair references

Analysis

Component	Description
Slope Analysis	Apply per-face slope coloring with a configurable legend range
Waterflow from Points	Trace terrain-conforming downhill paths from point sources to boundaries or local sinks
Terrain Sections	Overlay multiple terrain profiles and shade proposed-versus-reference cut/fill regions
Mesh Areas	Split a mesh by closed boundary curves
Mesh Collage	Combine meshes in 2D planning mode or as 3D colored terrain

Install

Rhino Package Manager

1. In Rhino 8, run _PackageManager.
2. Search for MoleHill.
3. Install the package to get the Rhino plugin and the optional Grasshopper companion together.

After installing, run mhPanel to open the MoleHill panel, or mhCreateTerrain to start a terrain from the current selection.

From source

Build it yourself (see Build From Source) and load src/MoleHill.Rhino/bin/Release/net7.0/MoleHill.Rhino.rhp in Rhino 8 with _PlugInManager. Copy MoleHill.gha to %AppData%\Grasshopper\Libraries\ for the Grasshopper components. In Windows file properties, unblock the files if Rhino refuses to load them.

Build From Source

Requires Windows, Rhino 8, and the .NET 8 SDK or newer. See CONTRIBUTING.md for prerequisites, validation and conventions.

dotnet build MoleHill.sln
dotnet build src/MoleHill.Rhino/MoleHill.Rhino.csproj -c Release
dotnet build src/MoleHill.Grasshopper/MoleHill.Grasshopper.csproj -c Release -f net7.0-windows
pwsh ./build-yak-package.ps1

Release outputs:

• src/MoleHill.Rhino/bin/Release/net7.0/MoleHill.Rhino.rhp
• src/MoleHill.Grasshopper/bin/Release/net7.0-windows/MoleHill.gha
• .artifacts/yak/MoleHill-<version>/molehill-<version>-rh8_9-win.yak

build-yak-package.ps1 stages a Rhino 8 Windows Yak package that includes both the Rhino plugin and the optional Grasshopper companion under net7.0/.

Test

dotnet test tests/MoleHill.Core.Tests/MoleHill.Core.Tests.csproj
dotnet test tests/MoleHill.Grasshopper.Tests/MoleHill.Grasshopper.Tests.csproj

License

This repository is mixed-license.

• MoleHill-authored code outside src/TriangleNet/ is licensed under GPL-3.0-only, with an additional permission to combine it with the TriangleNet subtree.
• src/TriangleNet/ is excluded and retains its upstream notices and terms. It derives from Jonathan Richard Shewchuk's Triangle, which may be freely redistributed without charge but may not be sold or included in a commercial product without his license. Using MoleHill in your own work, professional work included, is unaffected; selling MoleHill or shipping it inside a paid product is not allowed without that license.
• Clipper2 (Boost 1.0) and BitMiracle.LibTiff.NET (BSD-style), shipped with the plug-ins, retain their own terms and notices.
• The MoleHill code is intended to be reciprocal: if you distribute modified versions, you need to provide the corresponding source under GPL terms.

See LICENSE and the files under LICENSES/ for the details that apply to each part of the repository.