AutoCAD Civil 3D

[#1]

Hello all,

I am in need of subtracting Surface A from Surface B to display the surface intersections between the two. I have a geological top of clay surface and a bottom of clay surface where the bottom intersects with the top thus showing holes in a geological clay layer. I am wanting to know if Civil 3D supports the subtracting of two surfaces.

Thank you!

[#2]

brian_ranstead@urscorp.com wrote:

> I am in need of subtracting Surface A from Surface B to display the
> surface intersections between the two. I have a geological top of
> clay surface and a bottom of clay surface where the bottom intersects
> with the top thus showing holes in a geological clay layer. I am
> wanting to know if Civil 3D supports the subtracting of two surfaces.

Don't claim to be an expert, but you should be able to create a 'Volume
Surface', using care in specifying the order of base/compare surfaces.

Then contour elevation 0.0.

Terry
--
Never start any job without the right tools!
AutoCAD Add-on Tools at http://www.dotsoft.com

[#3]

Terry, if you are just trying to get the intersection of the two surfaces, the order they are added (base vs. comparison) doesn't matter.

Brian Hailey
http://www.cad-1.com
http://www.AtYourDeskTraining.com

[#4]

BrianHailey wrote:

> Terry, if you are just trying to get the intersection of the two
> surfaces, the order they are added (base vs. comparison) doesn't
> matter.

True, but todays 'just' is often tomorrows 'first of many', so might as
well build it right today.

Terry
--
Never start any job without the right tools!
AutoCAD Add-on Tools at http://www.dotsoft.com

[#5]

Terry

When i do what you say, the result volume surface is in the wrong elevation.

Example: my surface "1" is in (+-) elevation 235.600 and my surface "2" starts from 235.850 to 235.450 (it's like a cup), when i do the volume surface, the result goes to elevation 0.0 (+-), and when i do contour elevation 0.0, it gives me the interserction but in the wrong elevation! how do i put this in the right elevation? because what i want is the (surface 1)-(surface 2)

thanks for your time

Ivo Costa

[#6]

The elevation you're seeing is the difference in elevation between the two surface; surf 1 minus surf 2. This is what it seems like you asked for. So you have your contour line representing where they intersect and all you need now is its elevation to match the surfaces?

Turn it into a feature line and use the surface from elevation tool.

[#7]

If you don't have a good understanding of how Sites work within Civil 3D, I would recommend that you don't use a featureline, just use the same tool and assign the elevations to the polyline instead. If you want more inforomation on why I recommend this, check out THIS.