A set of tools for mesh modeling is included within the Autocad 3D range of modeling tools and functions. Autocad creates what's called a polygon mesh, which is a collection of vertices, edges and triangular faces making up an organic solid. This object as a whole is known as a TIN or triangulated integrated network. Triangles are the most efficient shape to encompass and define an area of space, and as such are the best shape to use in building organic forms. Such meshes are often used when creating terrain for civil or urban planning. They are also used to create the type of plastic, non-geometrical forms found in product design.
When first starting out with meshes, we first create a new document using one of Autocad's 3d templates - these ship with the program, but can be modified and resaved as your version of the template. Then ensure that you're working in the Autocad 3d workspace - to do this see the bottom right workspace shifter. This reveals a set of 3d tools in the top Ribbon area of the PC interface. To create an organic mesh model, go to the Mesh Modeling section of the Ribbon and choose Primitives from the Mesh tab. Next click the small arrow at the bottom right of the tab to launch the dialog box. Then In the Tessellations section, which represents the faces, type: Length 3, Width 3, Height 3, and finish the command by clicking on the OK button.
We next choose the Mesh box tool from the Ribbon. The Command line asks use to specify the first point; in this case choose the 0,0 point, then type 5000, and hit the Tab button to move to the next field, type 3000 and hit the Enter key, and type 2000. Next select the box and right-click the mouse to choose Smooth More. Then increase the smoothness by hitting the Enter key twice. The Smoothness will be set to Level 3; this can be seen on the tool tip. It's possible to reshape the object by holding down the Control key and selecting two of the object's faces. Note that the Gizmo axes will now highlight in yellow. We move upwards by 2000, for example, and then right-click on the Gizmo to select Rotate and type in 45 degrees to add some curvature to the shape.
If you wish to manipulate some of the individual vertices go into the Wireframe mode by typing VS into the Command Line and choosing 3. Then click on the Sub-object tab and hold down the No Filter button to see the dropdown. Note now the settings for Vertex, Edge and Faces. We can select the Vertex and pressing Control add to the selected vertices. We then highlight the Z-axis to pull upwards in the Z direction; we can also type in a value and hit the Enter key on the keyboard to complete the command.
We may also split the various faces of the object, as well as create sections and loft terrain. Meshes may also be created from curves and splines. As can be seen, the variations and possibilities are endless. Furthermore, materials and lighting can then be added, like any other 3d object in Autocad, and animated videos may be created from such mesh models.
Tom Gillan has been training Autocad 3D to corporate clients in Sydney for seven years. If you like to know more about Autocad 3D, visit Design Workshop Sydney for more information.