Autocad 3D lofted terrain

by Design Workshop Sydney

Lofted terrain is often used in Autocad 3D when creating architectural models for shadow-mapping. We show you how in our Autocad 3D training courses.Lofted Terrain in Autocad 3D

First of all go to the top left Application menu (Mac: File) > New drawing and choose your metric template. Double-check the drawing space limits by typing limits into the Command Line, then type 200000, 100000 followed by Enter (which will give you a space 200 x 100m).

Next we create a closed poly-line using the Rectangle tool (REC), say 30 x 50m.

To create the topography go to the Spline (SPL) tool and turn OSNAP off (F8). Create a few contours, for example 6 or 7, and draw these contours beyond the property lines. Note that the Poly-line tool would give you sharp edges unless you choose the Arc option in the Command Line.

Orbit your view around so that you can see the vertical Z elevation. Turn Ortho back on (F8) on. Select each spline and move the Gizmo upwards by a couple of metres (2m, 3m, 4m, 5m, 6m, etc), or use the Move tool. To keep the original splines visible after the Loft operation you can type delobj and type 0 – this is the System variable for delete object.

Lastly to create the smooth surface select the Loft tool (in the set stacked under the Extrude tool). Then select the splines from the bottom upwards or the top downwards – either way will work. Then select Cross Section Only – note that Smooth Fit is the default, and hit OK. This will result in a smooth lofted terrain as shown here in the illustration.

The 3D interface in Autocad is user-friendly and easy to learn, and we take time to teach a wide range of techniques in our classes, which include modeling, materials, lighting and animation. You can see many examples of our class work on our Facebook page.

For more information there are lots of resources on the web, but try the Autodesk site to begin with: Support options and user forums are also available from the home page.

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