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Workflow for Automated Milling of Site Models

This page considers a workflow for milling site models. Aas usual, we begin with by developing a clear description of our intentions conceptual model. This will help us to specify our information needs. For deeper reading on why we always start out our workflows with a conceptualization of the problem, take a look at:

In developing a workflow, it is important to think it all the way through. In this case, we need to consider what sort of information the Milling Machine needs, and specifically, what information is needed by the MasterCAM program. In short, our conceptual model will be very simple. We seek to represent in a physical foam model:

Conceptual Model

  • A terrain surface
  • Building massing and other flat-topped protrusions

This is not the most complicated problem that we might set for ourselves, but it is a fairly common sort of model that a landscape architect or urban designer might make.

Data Model for MasterCAm

  • a continuous mesh of polygons or NURBs, that has no undercuts or overhangs or rips of any sort. This terrain mesh should not be any more complicated than it needs to be, since MasterCAm is a little finicky.
  • Surfaces representing the tops of our extruded geometry this layer will serve to identify the flat places that need to be milled, and also to serve as a check to prevent the milling of the terrrain under the buildings.
  • The Terrian intersection curves of the extruded objects. These are essentially the tops of the buildings projected onto the terrain surface. This geometry tells the router how far down to go when milling the sides of the buildings.

Workflows and Tools

There are many ways to prepare a terrain mesh. IN our experience the best terrains are made with delaunay triangulation. It is especially useful if you have an interpolator that understands how to contol the surface with hard and soft breaklines. We will spend a few minutes with this sample dataset exploring some easy techniqges for making terrain from contours and terrain from breaklines.

  • Demo Dataset (Condor Street Wilds)

    Praparing a Terrain Mesh

    In class we will discuss the following

    • Obtaining Terrain meshes into sketchup from the Google Earth repository
    • Editing meshes in Sketchup with the Sandbox Tools
    • Obtaining CAD contours form from the USGS or from The GSD's 3d Modeling Infrastructure
    • Modeling by working contours in CAD and Interoplating contours in Sketchup
    • Another approach with breaklines and masspoints using ArcMap or AutoDesk Civil Design .
    • INterpolating contours with the Rhino Delaunay Plugin (pointset reconstruction).

    Preparing MasterCAm data in Rhino

    There are undubtedly many ways of preparing the specific geometric information to instruct the milling machine. We have chosen to illustrate the procedure using Rhino. Rhino is capable of bringing in geometry from Sketchup or autodesk formats. It also has powerful tools for transforming and validating surface informtion and for creating the terrain intersection curves for buildings, given their tops. Ultimately we use rhinop to scale the model, prepare the needed geometry and export it to STEP (Standard for the Exchange of Product model data) files that are used by MasterCAM.. YOu will find a demo dataset and a step-by-step procedure in the links below.

    • Download Demo Dataset THis demo dataset includes a site model if Condor Street Urban Wild. It includes alternative versions as developed using each of the emethods described above. Resources related to the Rhino and Mastercam are located in the MasterCAM folder.
    • Click here for step-by-step instructions

    Preparing Router Job using MasterCAM

    MasterCAM is the tool we use to prepare jobs for all of the Computer Numerically Controlled tools in the GSD's CAD/CAM Suite. Stepen Hickey, director of the lab has prepared the folloing documents oriented toward this specific workflow of creating a milling job for a digital site model. If each person uses the template file linked below, and the procedures documented in the links provided below, then several models can be arranged into one job and milled at once!.