# Physical Modeling 6.1 [topography method 1]

## “Generating a Topographic Model from Rhino (Option 1)”

1. Begin with a NURBS surface that represents the desired topography that you would like to build a physical model to represent.
2. Follow Rhino 5.20 [contour] to create a series of horizontal contour lines (direction perpendicular to the z axis) that divide the surface into even intervals of desired height (use image below to pick desired interval) You will need to establish your “direction perpendicular to the contour lines” as the z-axis.
• Note: You should use the spreadsheet at the end of this tutorial to determine the desired contour interval based on the thickness of the physical material you will use to model each contour at the scale desired for the model. For example, if you are modeling topography at 1/16”=1’ scale and your are using cardboard (5/32” thick), your contour interval would be 2.5’ or 2’6”.[Premium Content - Login] [Membership Options]
3. With your new contour lines on a new layer (hopefully named “Contour Lines”), use the point tool to create a point on each end of every contour line. (If you are comfortable with c-planes or would like to use a c-plane method, skip to step 8 or follow Physical Modeling 6.5 [topography with cPlanes]).
4. Select all of the points on the left side of the contour lines and use the Rotate3D command (Rhinoceros Tutorial 5.6) to rotate the points flat (on the x-y plane).
5. Now, draw a series of stepping lines connecting each of the points you just rotated. (See example below).
6. From the second level point, draw two perpendicular lines that connect to the last point (See example below).
7. Use the Trim and Join commands to create a closed, stepping polyline. You will need this later.
8. Instead of using the points and Rotate3D command, you can change your c-plane to be parallel to the edge of your contour lines for one side. (See Rhino 5.36 [cPlane])
9. Next, repeat for the points on each side of the contour lines.
10. With your contour lines back on, draw a rectangular surface on the ground (x-y plane) below your contours. Make sure the surface is larger than all of your contours (Hint: Switch to top view to make sure!)
11. In the top view, use the Project command (Rhinoceros 5.13 [project]) to project the contour lines down to the surface drawn in step 9.
12. Delete the surface after completing the projection. Now, change alternating contours to different layers (One layer should contain lines 1, 3, 5, etc. and the other 2, 4, 6, etc.).
13. Using the Rectangle: Corner to Corner tool, draw a rectangle that encloses all of the contour lines.
14. Select all of the objects and perform a reference scale to make the full size drawing into the desired scale for building your model. For example 176’ at 1/16”=1’ scale would be 11”.
15. Copy all of the contours object and move them adjacent to the original.
16. On the copy, delete the odd contours (1, 3, 5 etc.) leaving the even contours. On the original, delete the even contours (2, 4, 6, etc.) and leave the odd contours. You now have two sets of contours that you will eventually use to create the final topographic model.
17. Now, draw a rectangle 24” wide by 12” tall and assemble all of your pieces inside. This rectangle represents the cutting bed of the laser cutter.
18. Select all of these objects and choose File>Export Selected. Change the “Save As Type” to AutoCAD Drawing File (.dwg). Give your file a name (remember naming conventions) and save it to your flash drive. Choose “2004 Lines” as your Export Scheme.

Video Demonstration (Includes Rhino 5.20 & Rhino 5.24):

Physical Topographic Modeling (Part 1) - Lecture 215, Spring 2015 on Youtube.

Physical Topographic Modeling (Part 2) - Lecture 216, Spring 2015 on Youtube.

Assembly of Physical  Model on Youtube.