Intersecting SURFACE Boundaries

Some time ago... a day, a week, a month, who knows, I wanted to compare 2 TIN Surfaces and figure out the EXACT location of where the Surfaces touched. Ended up coming up with these steps: 

         1. Create a TIN Volume Surface 

         2. Ran am Analysis to User Contour Elevation 0

         3. Then Extract the Created User Contour as a Line 

Start by Creating a New TIN Volume Surface

(in this example a POND will be compared against a CROSSING plane) 

The Volume Surface is calculated from elevation 0, it will appears below the TIN Surfaces. 

To simplify view set TIN surfaces to No Display, and leave VOLUME Surface on

The Volume Surface is shown here using a Tin & Points Style. Notice how the Pond hole is filled up. A Surface Analysis to a User Specified Contour needs to be done to find the intersecting boundary.

Before running the Analysis, make sure the User Contour component is visible in the used surface style. The color has been changed to RED for it to stand out in Plan View

Then the VOLUME Surface Properties dialog box to the Analyses Tab, Select User-defined Contours as the Type. Presses on the Range to 1 and In the Range Detail area set the Elevation value in the row to 0.00

The result should be a POLYLINE marking the location of where the 2 Surfaces intersect.

The resulting Boundary Outline can be extracted. By selecting the surface and going to the Contextual Ribbon. From the Tools Panel use the Extract Objects and Uncheck everything except User Contours.

The final product is a 2D AutoCAD Polyline, that can be selected and edited.