This came up earlier today as a Takeoff User question
I have a Surface Model that I have created and I need to determine the surface area of the model for the Rip Rap placement that we will be constructing - how do I do that?
The Find Surface Area command does a nice job of computing the surface areas, and you can use it to compute the areas between lines defined as Breaklines (e.g. Top and Toe of slope) or between lines defined as "Sharp & Texture Boundary in the Surface Sharpness property of the line.
In this example the user has created the pond surface using a combination of Contour lines and 3D breaklines and initially they had them all set to Sharp & Texture Boundary - so when they tried either Breakline limits or Texture Boundary Limits nether allowed them to select the entire surface.
In the video below, we show how to best set up the lines and their properties to be able to use the Find Surface Area command successfully to generate just the result needed.
Hope it helps