Extrude to Multipatch not creating closed features

[SamLevy]

I have a set of two tins, one with surface features and the other just a flat area some distance underneath, and a polygon, all of which are the same dimensions.  I extruded the polygon between the two tins and the one time that it worked it does not seem to be closed.  I am doing this in order to create a shadow map by completing a 3D Intersect of the skyline barrier product with the multipatch landscape.  I checked the skyline barrier already to see if it was the cause of my problems, but it actually is closed.  When I checked the landscape multipatch, the tool either failed or completed and gave me a blank output.  I assume this means that it is probably not a closed feature.  I'm not sure where to go from here.  Thanks in advance for any help you can give me.

[JeffreySwain]

You said that your TINs have the same extent, I would consider moving one just inside or just outside the spatial extent or utilize the Extrude between and keep the TINs the same extent, but make the polygon being used just inside.  I have discussed this workflow before in this blog to create a block diagram.

[SamLevy]

First, thanks for the help.  Unfortunately, I have met with some disappointment:

I attempted the second option (TINs the same extent, the polygon smaller) with the same results.  I tried running the Is Closed 3D tool on the resulting multipatch and it failed with a generic error message.

The first option (one TIN larger extent, the other TIN and polygon same extent) failed and crashed arcscene.

[JeffreySwain]

I would process the attempts in ArcMap, since ArcScene utilized video card memory, once you are out of it - crashes.  You can always run the tool in ArcMap and view results in ArcScene.

[SamLevy]

I ran it again, this time in ArcMap, but the only difference was that it created the multipatch.  The output was still not closed, however.  Or rather, the Is Closed tool failed and created a blank output in the IsClosed column.  I'm not sure if this means that the multipatch is not closed or that the file created by the Extrude Between tool is for some reason not useable.

[SamLevy]

I think that the TIN was actually just too complex.  Not a satisfying conclusion, but thanks for the help.  I just ended up using a TIN created with 2 ft contours.