Using Grading Tools to Create and Flat Surface

[nrogers58]

I have yet to figure out how I can create a flat surface using the grading creation tools. Specifically, I use the grading tools to create finished site grades.  Then I paste the existing grade surface with the grading surfaces to create a finished surface.  Using this procedure, I have tried to set finished floors for the structures and paste them to the finished grade with a 6" vertical rise to the finished slab elevation. I tired to set a horizontal feature line at the finished floor elevation and set it as a break line in the finished surface. The result is not flat?

Should I be following a different work flow and what might that be?

Thanks

Neal

[Matheus-Lima · Accepted solution]

Hi @nrogers58, instead of breaklines, I would create a closed feature line with all points at the same elevation, use the infill option and create a surface from it. This way 100% sure the grading surface will be flat and you can paste it in a composite surface to see the results. 

A picture or two would help a lot, btw. Cheers,

[brian.strandberg · Accepted solution]

Neal, as you elevate those slabs 6" vertical rise, how are you doing that?  When you do truely vertical surfaces in Civil 3d, it can cause problems in the surface.  Civil 3d uses delaunay triangulation to create surfaces, and the main restriction is that no single X & Y can have more than one Z value.  

If you try to create a single X,Y with two Z's, I'm not sure which one it will use.  As a result, which Z it uses will be unpredictable.  If you include an even tiny offset (0.00001), that will work fine.

[Joe-Bouza · Accepted solution]

offset your pad grade feature line inside a tad to the FFE then add an infill, done

[nrogers58]

Thank You all