AutoCAD® Civil 3D® 2012 Essentials: Autodesk® Official Training Guide: Essential

Understanding Surfaces

As you might guess, the game of 3D connect-the-dots is a bit more sophisticated than the 2D version. In addition, you need the result to be a 3D model rather than just lines. To accomplish this, you need to apply a computer algorithm that connects the dots in the most efficient and accurate way possible. This algorithm is known as a Triangular Irregular Network or TIN.

The TIN algorithm works by connecting one point to at least two of its neighbors using 3D lines. As each point connects to two or more of its neighbors, the resulting model looks something like a spider web made up of triangles (the T in TIN). Because the spacing between points is typically nonuniform, the triangles come in many shapes and sizes—which is ...