Composite Volume Error?

[Phil Ferguson]

Any suggestions?

Same stratum...same site...

Composite volume shows 62810 cy cut...106937 cy fill

Grid volume shows 62851 cy cut...83807 cy fill (grid is set up with m & n value = 1)

I'm not finding any holes or spikes in the surfaces

I expect there to be some difference between them, but this is not what I expected.


LDT 2004-sp1

[mjfarrell]

Go to surface display Slope Banding 2d solids
and have it do say 7 slope ranges.

I suspect that you will find vertical faces in your
model are the cause of the problem.

That or re-run the data with a much smaller grid size and
see if they do not come into closer agreement with each
other.

Or set the volume surface current and generate contours and look to see if they make sense
NOTE the contoures will be 'relative' not actual elevations.
So a 1 foot fill will be the 1' contour line......

[Phil Ferguson]

Go to surface display Slope Banding 2d solids
and have it do say 7 slope ranges.

I suspect that you will find vertical faces in your
model are the cause of the problem.

That or re-run the data with a much smaller grid size and
see if they do not come into closer agreement with each
other.

Or set the volume surface current and generate contours and look to see if they make sense
NOTE the contoures will be 'relative' not actual elevations.
So a 1 foot fill will be the 1' contour line......

I imported the grid of 3d polylines for the composite volume surface. You were right, there are spikes.

I didn't notice before, the maximum elevation in the volume surface statistics is 803 (a bit excessive). How would you go about getting rid of the vertical faces?

[MHultgren]

If you have breaklines defined, you can edit\redefine them. If not, edit the triangles or try swapping the triangle faces and see if that helps get rid of the spikes. If the surface is created using points, check the point elevations. It all depends on how the surfaces were created, garding objects can be manipulated , points can be editted, or breaklines modified or replaced. Then rebuild and make sure the Apply Edit History box is checked.

[mjfarrell]

this is what I expected

I don't want to throw a 'shot gun' approach
to this. Why? Because this IS an engineering
design, and I would rather have the user contact me
off-forum so that we can discuss actual project
constraints and how that may impact any of the
corrective actions required to 'fix' this problem.

Sending user contact information in Private Message....
hold on Paul help is on the way!!!!

[mjfarrell]

The users results of importing the 3d faces for his volume surface reveal a SPIKE.
This spike in the volume data is most probably the result of the Exisitng ground model having a 'hole' in it, thus cuasing the unusually large volume of fill as reported when he calculates his site volumes...

The solution is to rebuild the exisitng ground model and avoid using any edit methods that would recreate the hole, and then use this un-holy surface in the strata definition to re-calculate
the site volumes.