Symbol Z Offset weirdness in ArcGIS10

[AnthonyFarndon]

In ArcGIS9x, if you have a 3D symbol (lets say a cone) and set it's Z Offset to 10 (lets say real world units of metres used), then it would place it 10m above the terrain.

However, in ArcGIS10, it seems to be a ratio of the symbol size. So if my cone size is 8, and I set a z offset of 10, it puts the cone 80m above the terrain. Put the z offset to 2, and it places it 16m above the ground.

It gets even weirder if you have a multi-layer symbol. If I have a cylinder of size 10, and a cone of on top of size 8, the z offset of the cone now gets applied from the cylinder size. So in this scenario, the cone is 10m off the ground with a z offset of 1. Remove the cylinder from the multi-layer symbol, and the cone goes back to being 8m off the ground.

Anways, if everyone is still with me, is this by design in Arc10, is it a bug, is there any way to return some normaility to it all?

If by design, can the documentation be updated, as it gives the impression it should behave the same as in 9x.

[JakubSisak]

I did not experience the same thing but something similar. I had a line feature class and I set the base height to a TIN. Then I extruded the line which looked fine like a fence. I then wanted to make this a multipatch so I saved and exported the Layer file to Multipatch. When I brought the multipatch into the scene it was way above the surface.

So in my case the fix was to interpolate the feature class shapes into true 3D features using the same TIN.  I then repeated the process with the 3D lines and it worked "as advertized".  I think there something funky going on if you set base height an existing surface and then tinker around with the 3D properties and symbology. 

Try interpolating your shapes to 3D then try symbolizing again.  You are right that this should work especially because many people use symbology to create globes, cubes and other 3D symbols then convert to multipatch and calculate volume, etc.