Volumes By Triangulation is an alternative volume method that compares two triangulation networks. This method is different from the grid based volume routines (Volumes By Layer, One Surface Volumes, Two Surface Volumes, Stockpile Volumes, etc.) and the cross section volume routine (Calculate Section Volume). Volumes by Triangulation calculates faster in most cases than the other methods, and it is the most accurate because it uses true TIN to TIN primodal volumes. This added accuracy in general is very small. The grid resolution is usually sufficient to model the surface for the grid based volumes. The Volume By Triangulation accuracy applies well when there is a feature like a 5 foot wide ditch. Then the grid resolution would need to be less than 5 foot to model the ditch which might be difficult on a large site.
The disadvantage to this routine is that it lacks the output options that help the analysis of the volume such as Difference Contours. Also Volumes by Triangulation does no extrapolation and stops calculating volume at the perimeter of the smaller of the two triangulation networks. Volumes By Triangulation is better when used with point data instead of contour data because contour data requires triangulating all the contour polylines as breaklines which creates a large triangulation network and is slower.
The triangulation networks to compare are defined in .tin or .flt files that are created by Triangulate & Contour with the Write Triangulation File option. Note that while both file formats are supported, the newer binary triangulation file format (.tin) is twice as fast to load and save, and half the size, of the .flt triangulation file format. For this reason, the .tin file format is recommended. Before using this command, run Triangulate & Contour twice to create an triangulation (.TIN or .FLT) file for each surface. The volume calculation is limited by either the extent of the triangulation networks or by an inclusion/exclusion perimeter(s). These perimeters must be closed polylines.
Output data includes area, tons by density, average thickness, shrink and swell, ratio, and total volume.
Select EXISTING surface Tmesh File
Choose an .flt or .tin file
Select final elevation or surface
TIN [Elevation/<TIN>]? press Enter
Select FINAL surface Tmesh File Dialog
Choose another .flt or .tin file.
Choose Predefined Boundary Dialog Choose none.
Select Inclusion polylines select objects
Select Exclusion polylines select objects
Volume Report Choose viewing option
Comparing Triangulation files: C:\SCAD2006\DATA\TRI1.FLT
and C:\SCAD2006\DATA\TRI2.FLT
Cut volume: 66891.35 C.F., 2477.46 C.Y.
Fill volume: 43458.01 C.F., 1609.56 C.Y.
Pulldown Menu Location: Grading
Keyboard Command: trivol
Prerequisite: Two .flt or .tin files
File Name: \lsp\contour4.arx