Topic: volume surface - above base surface only

[jcoon]

I'm looking to get a volume surface of only above the base surface (see attachment)
when I generate a volume surface from (eg) as base and (fg) compare surface I end up with the cyan surface.
I'm after a volume surface that looks like the figure to the right which only includes the (fg) surface above the base (eg) surface and a user contour
at the intersection of the two surfaces.

its pretty much the same as a soild being cut at the eg plane

Thank you
John

[huiz]

You can create poly lines at the intersection of the two surfaces (find the minimum distance) and use that as a boundary to cut the unnecessary surface.

[jcoon]

Huiz,

Thanks for the reply. My goal was to create a volume surface above the selected base surface only. I've been able to create the typical volume like the figure to the left with dot net but I still need to get the zero contour by the user-contours. I just thought there might be a way to control what parts of a volume surface I get. I thought that if I could control getting the volume above the base surface only by hand or selecting objects like you noted that I could figure out a way to do it with dot net.

Thanks
john 

[huiz]

I'm not sure if you can do this with dot net but there is a function to get the intersection of two surfaces in poly lines. Then you can use them as boundary for the volume surface, so you get the upper part only. Or do I not understand the question?

Volume surfaces are always the difference, calculated from zero elevation, not a base elevation.

[jcoon]

Huiz,

I was able to create the volume surface calc from zero like you said. I thought they might have something that would allow you to do it based on a plane. oh well.........thanks for helping