problem with triangle volume calculation

[cr_raul]

hello Lars,

I'm trying to calculate some cut volumes but when using  the "almost exact" method I get an error stating "Projected surface mismatch" and that there is a difference between Loaded and Projected surface.
This a volume calculation for a pit and I triangulated the existing (top) surface from a 3dpoly - the top perimeter- and the design (lower) surface from another 3dpoly - the bottom perimeter - and the first one. And another thing is that all the volumes appear in the volume report in the fill column but with negative values.
I attached the dwg. containing the 3dpolys, the triangles and the tsd files.
BTW I'm using the latest cadtools verison and Acad 2011 on WinXp.


Best regards.

[Lars]

Hi!

Sometimes when perimeters of booth surfaces are close to each other this error appear. To make sure the top surface overlap, try to extend the top surface (Existing ground) by offsetting the perimeter and retriangulate. You should set your "Existing ground" as Original and your pit bottom surface as "Design"

/Lars

[cr_raul]

well I found out what was the problem after I plotted the resulting triangulation for volume calculation. there were several bad triangles in that triangulation and after removing them I've retriangulated that surface and used it as a new design surface, and this time the results were correct. so that error saying that the resulting area is different than the original area was because of those "extra" bad triangles that added up their area value to the initial area.
in time, I got used to checking the triangulations before saving them as .tsd but it would be nice if you had the time to check the triangulation algorithm and eliminate these bad triangles that seem to cause  the most problems.
also it would be nice to plot the triangles from the volume calculation as cadtools triangles so after making some corrections we could save those triangles directly not by making a new triangulation from 3d faces.

[Lars]

Great that you found the problem. I agree it would be nice if the alghoritm could manage it better.
Saving the volume triangulation can be done by using the "Edit surface" and "Import" in the menu. There is no need to retriangulate.

/Lars