Issues with volume calculations

Trying to work out the difference in volume between 2 different contour plans with sandbox. When using sandox it does not create a clean plane around the area. See images. Thanks

Triangulate the areas where faces are missing. Maybe only one or two edges per side will fix it.
Note that you may need to enter the group for edditing.

p.s. otherwise please share the file here.

A.skp (628.0 KB)

Do you mean just redraw the contour that is causing the issue? I’ve tried redrawing the surrounding rectangle but not the contour

The result from ´From Contours´ is a group, leaving the original contour lines unchanged.

Enter the result group and add edges with the ´Line´ tool to triangulate the missing parts. See:

The red lines indicate where to draw them. They are supposed to represend (one per side) two straight edges. You may have to draw several per side. Zoom on on the lowest contour line to see the segments and endpoints where the edges should go.

p.s. Turn on ‘Hidden Geometry’ to see how ‘From Contours’ triangulated your model in the operation.
(Menu View > check ‘Hidden Geometry’).

Thanks for the help Dan, but unfortunately I still can’t work out where the missing lines should be after some trial and error.

You just need to edit the surface group and drawn in two edges over the top of the perimeter edges - see the blue ones…

You can then smooth the few edges which are now located within the surface [use the context-menu to smooth or Erase+Ctrl ]

Thanks @TIG and @Wo3Dan I now have a complete face. However, I still can’t retrieve a volume calculation.

I have a value for the component on the right but not the left. I’ve tried intersecting the faces etc, but still nothing.

Any ideas? Thanks again
A.skp (2.3 MB)

A ‘solid’ has a volume.
A ‘solid’ can only contain geometry.
Your component contains a nested component that is the ‘surface’
If you explode that so the outermost container only contains geometry it will report a volume, if it is solid.
SolidInspector² had to fix a few errors to make it report ‘solid’…

A[tig].skp (2.8 MB)

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Thanks @TIG really useful, cheers for the advice