Cutting Volumes along a set line

[Jestoner]

I apologize if this has been posted but i wasn't sure how to search for it and my searches came up a bit empty handed.

I am attempting to take two surfaces and cut straight down through a set polyline and get the difference between two surfaces.  Do i want to use the bounded volumes to do this? Or can i simply create two surfaces and and use the analyze/volumes tool and just select the two.  I would then add the boundary to each surface to limit the data.\

My concern is since the two surfaces do not meet along the edges which will cause the math to be off.

[troma · Accepted solution]

I've never used the 'Bounded Volumes' tool, but I guess it will probably work.

Otherwise, just make a new surface, paste one of your surfaces into it, and add the polyline as a boundary. Then you can use the regular volume analysis or a TIN volume surface. Either way will work. So long as one surface is totally within the bounds of the other, I've never had problems.

[Jestoner]

Thank you so much, that's what I tried first I just wanted to verify my solution was correct.  I tend to second guess myself a lot as i am still fairly new to Civil 3d tools.

[ccoles]

I use 'bounded volumes' all the time, and have checked to make sure the bounded volumes still add up to the full surface volume. The checks always come out right. It makes separating volume areas within your design a quick, easy task.

In the Volumes Dashboard in C3D 2013, They have taken bounded volumes to a whole new level, and I like the way it does the volume reports and separates the bounded volumes within the tool and on the reports. If you are running 2013, you should check it out.

[neilyj666]

---

Jestoner wrote:the data.\

My concern is since the two surfaces do not meet along the edges which will cause the math to be off.

---

The calcs will be correct as it is just a cookie cutter type calculation (i.e. vertical) but practically you might miss some volumes (in the slopes) at the edges which could be a problem

[Jestoner]

That should have been the question i asked, whether or not it sliced straight down, thanks!

[ccoles]

Yes, it cuts up and down, like a wall at the polyline.