The first node to add is a subdivision approximation node. To add it, select the desired geometry and click the Create option. For the octopus, both the nautilus shell and octopus body are selected. They share the same approximation node. (Figure 4)

Once created the node can be modified through the attribute editor. Either click the Edit option or select the approximation node in the hypergraph and open the attribute editor. The subdivision node has several different approximation methods to choose from. For this tutorial the Length/Distance/Angle or LDA method is used. Upon selecting it, the length, distance, and Angle options become available for editing. To choose which method to use simple add a value above zero to one of the three sliders. Leaving a parameter at zero prevents Mental Ray from searching for those conditions. Only Distance is used for the Octopus and is set to a value of .1. The next set of parameters to modify is the Min and Max subdivisions. The Octopus was modeled entirely out of quads and contains no real surface detail. Because of this, we need high values to achieve the desired detail. Set the Min Subdivisions to 3 and the Max Subdivisions to 6. (Figure 5)