Best way to make a surface.

[adam_J]

I want to make a surface, below a surface. Say, the bottom of a body of water, or an existing surface and a known elevation to remove.

What is the best way to do this. I already have the existing Topo. Should I creat another surface using a .CSV file with N,E, and elevations that we want to remove to, then calculate a Volume?

THe volume is my ultimate goal.

Thanks so much for any help you can provide.

-me-

[sinc]

Is this actually under water, where the water level is at a constant elevation? If so, you should just be able treat your data like a normal NEZ file, create a surface from the points, then compare that to a flat surface at ELEV=0.

If you actually need to compare it to another surface that varies, then the easiest thing might be to still start with your NEZ data, but import this data into C3D, creating some "temporary" Cogo Points. Then adjust all these Cogo Points to the Surface elevation using "Elevations from Surface", and dump the points back out into CSV format. Now take that data, which has your surface elevation at each point, and combine it in Excel with your depth shots. Finally, import the result into C3D again as a new set of Cogo Points, but this time create a surface from the Cogo Points. This should get you your "bottom" surface.

[adam_J]

Well I have a water surface, then the bottom of that body of water ( a creek/stream).

I am going to edit the points for the bottom of the stream to reflect where I have to "go down" to for some soil removal. Then I would like to compare the surfaces, make some cross-sections and calculate volumes based upon the T.I.N. of each surface (if that is possible).

Thanks again for the info.