Hi,
Extending on Steve's analysis, when computing earthworks volumes the user
has to define a "Site".
If the user Imports both 2D boundary borders first they then have the data
they NEED to make the best estimate of the site location and in particular
rotation.
To get the most reliable computation for grid and cross-section volumes, one
axis of the site should be parallel to the longest axis of the area of
intersection.
It is very easy to select this angle graphically using the intersection area
of the polylines as a visual guide.
When prompted for the angle select a point to the left of the intersection
area and then a second point inside the quadrant between 45 degrees below
the X axis and 45 degrees above the X axis from the first point.
--
Laurie Comerford
CADApps
www.cadapps.com.au
"Steve Cannon" wrote in message
news:41825cca$1_1@newsprd01...
> Hi Mike,
>
> I agree with you that the 'not overlapped' message indicates that, in plan
> view, the EG and FG surfaces share no common ground. When this message
> occurs, Raj needs look at the xy locations of the two surfaces to see if
the
> two surface boundaries share a common area. The easiest check is to
import
> the 2d-border for each surface and perform a visual inspection. In Raj's
> case, I suspect it is most likely it is a coordinate base problem.
>
> I will disagree with you contention that: "In order to compare surfaces
the
> FG surface must be contained entirely within the boundary of the EG
> surface". LDT will compute a composite surface and volume for any strata
in
> which the two surfaces share ANY common area. The controlling surface
does
> NOT need to be contained ENTIRELY within the limits of the EG surface, any
> subset will do. In Autocad terms, for any given strata, if one imports
the
> 2d-boundaries for each surface, converts both to regions, and can perform
a
> solids intersection of the two regions without a null region being
created,
> LDT will compute a composite volume between the surfaces contained within
> the intersecting region.
>
> In applied practice, if one is aware of this, there some instances where
it
> could save some time. You are correct that in MOST applied land cases, the
> user will want to compute a volume over the limits of the entire
controlling
> surface, and therefore it is DESIRABLE to have the FG surface contained
> entirely within the boundary of the EG surface. The fact that the LDT
> composite earthwork routine reports neither a composite area nor an
> 'unsolved area' within its statistics often leads to user prepared reports
> that include unintended cut or fill omissions. Such a reported statistic
> would be a useful flag that one needs to re-examine the limits of the two
> surfaces. I have occasionally caught unintended omissions by importing
the
> 2d-polyline boundary of the composite surface, and compared its area to
the
> 2d surface area reported by the controlling surface's extended statistics.
>
> Users should never trust the reported cut and fill volume without doing a
> series of checks on the authenticity of those volumes.
>
> sc
>
>
>
> "Mike Norton" wrote in message
> news:418248f1$1_1@newsprd01...
> > Raj,
> >
> > In order to compare surfaces the FG surface must be contained entirely
> > within the boundary of the EG surface.The error message you mention
> > indicates this may not be the case.
> >
>
>