Setting Multipatch depths/heights to a specified measurment.

[ColeF]

Hello, I'm working on a really interesting project involving glaciers and their depths. I am trying to use complex multipatch shapes and extrude their depths to specific measurements (e.g 15 meters below my surface DEM). Is there a way to make the whole multipatch drop by the example of 15 meters?  These are irregular shapes, similar to the bathymetry of a lake. Any help would be appreciated, Thanks in advance!  

[JosphatM]

Are you working with existing multipatch features that you would like lowered by -15m or creating new features at -15m elevation from the lake's surface?

[ColeF]

I've created the multipatch features through the " interpolate polygon to multipatch" tool, and the original data came from a raster that I reclassified. 

What I'm trying to accomplish is to show the actual depths of the glacial ice throughout the glacier in 3D, I want to make my multipatch extend from the surface to -15m below the surface of the DEM, so I can visually represent it as well as determine volumes and estimate the topography below the ice. Instead of dragging the multipatch downward from the green ball that appears for that action, I'm looking for a way to evenly extend the multipatch features, so they extend exactly 15m below the surface of the DEM. Hopefully, that is a little more clear.   

[JosphatM]

Starting with your footprint polygon features, you can apply a uniform extrusion value (-15m) using the Extrusion Expression option.

This workflow is not available for multipatch features.  Left click and hold the green ball + D on your keyboard to enter an height value for your multipatch feature (suitable for small number of features).   

[ColeF]

Ok, thank you!