How do I create a composite surface that represents the LOWEST of a collection of stacked surfaces? (V8i SS3)

Question

Hi All, 
 I need to create a composite surface that represents the LOWEST of a bunch of surfaces which are stacked on top of each other at different elevations. Kind of like a 3D boolean addition but I only want single surface representing the lowest plane, or an upside down drape mesh. When it's generated properly looking at it from above it should appear as a concave hull. A bit hard to explain but if I were writing an algorithm to do it, this is what it would look like.. 
 Declare a bounding area "area1" 
 For each "x","y" point within area1 
 for each surface stacked at this point 
 if "z" is LOWEST 
 set area1 (x,y,z) 
 endif 
 endfor 
 endfor 
 Can anyone point me in the right direction on how to achieve this?

Ron Jones · Accepted Answer

Hi Tim, 
 If you can produce meshes rather than individual triangle shapes, you should be able to get your desired result with the following method. 
 
 Rotate to a front view. 
 Select all of the meshes. 
 Pick the Extrude Mesh Volume command, set the Direction to Vector , data point to accept the selection, and then define the vector pointing straight up a several thousand meters. You should now have a mesh volume. 
 Now use the Delete Mesh Facet command with the Block method and select the facets that extend up above your original imaginary surfaces.They will be deleted, leaving you with only the bottom hull of the mesh volume. 
 
 Cheers, 
 Ron

Tim T · Answer

Ron, thank you so much. This worked perfectly. I was able to modify the original design by selecting all the cells, then using the stitch into mesh tool. After that your instructions work exactly as described.