Calculate Volumes by Five Methods

For this tutorial, we'll be using a sample stockpile drawing and calculating its volume using five distinct techniques:

1. Stockpile Volumes: Creates grid surfaces from perimeter polyline and surface entities and calculates volumes in one command
2. Volumes By Layers: Creates grid surfaces from existing and design layers and calculates volumes in one command
3. Two Grid Surface Volumes: Calculates volumes between two grid files
4. Volumes By Triangulation: Calculates volumes between two triangulation files
5. Calculate Sections Volumes: Calculates volumes between two section files using volumes by average end areas

Each of these routines has its own advantages. You can choose the routine that best suits your data or run multiple methods as a check of the volumes. The volume reports for each of these routines will vary slightly due to using different types of surface models that have different resolutions. These volume differences should be less than 2%.

A Results Summary of the various volume methodologies is also provided.

If there is a greater difference, try increasing the resolution of the surface models. For grids, make the grid cell size smaller and for sections, make the station interval smaller. If there is still a significant difference, then the cause should be investigated by checking the source data.

Common Steps

The following are common preparation steps for all five volume methods:

1. Click the Windows desktop icon for Carlson to start the program.
   • If you get the Start Page, pick Open Files.
   • If you get the Startup Wizard dialog box, click the Browse button.
   • If you are taken directly into CAD, click File -- Open.
   Browse/navigate to the default folder location of C:\Carlson Projects and open the example1.dwg file.
   
   Use the File -- Save As to save a copy named example1-v.dwg. Completing this tutorial will alter the drawing file and by renaming the file from the start, you'll keep the original file intact (allowing you to run through the tutorial a second time if desired). This is also a good practice to keep when working on drawings from 3rd parties.
2. Ensure you are in the Civil program by issuing the Settings -- Carlson Menus -- Civil Menu command. Since our drawing contains point data, let's house it in a related coordinate file for future use. Issue the Points -- Set Coordinate File command to display a dialog box similar to that shown below:
   
   Set the value as shown above and click Open when ready. Next, issue the Points -- Point Utilities -- Update CRD File from Drawing command (also found under Points -- Coordinate File Utilities) to display a dialog box similar to that shown below:
   
   Accept the default values and click OK when ready. When prompted:
   
   Select Carlson, LDD, Softdesk, InRoads, EaglePt, Geodimeter, Leica or MicroSurvey Points.
   [FILter]/<Select entities>: type ALL and press Enter
   [FILter]/<Select entities>: press Enter
3. Due to the shape of the data (and in an effort to get consistent results), we'd like to develop a boundary (or inclusion) polyline around the data set. There are several ways to accomplish this:
   • Through the use of the Survey module and its Survey -- Draw Field to Finish command, or,
   • Through the use of the Draw -- 3D Polyline command, or,
   • Through the use of the Draw -- Shrink-Wrap Entities command, or,
   • Through the use of the Surface -- Stockpile/Pond/Pit Volumes -- Draw 3DPoly Perimeter command (run it now) to display a dialog box similar to that shown below:
     Set the values as shown above (click OK when ready) and when prompted:
     
     [Continue/Extend/Follow/Options/<Pick point or point numbers>]: type the range of 2000-2028 and press Enter
     [Arc/Close/Distance/Extend/Follow/Line/Undo/<Pick point or point numbers>]: type C and press Enter
     
     
   The drawing should resemble that shown below:
   
   Let's begin the volume calculation processes.

Volume Method 1 - Calculate Stockpile Volume

The Calculate Stockpile Volume routine is based on a grid surface methodology like the Two Surface Volumes discussion below. The difference with this routine is that it builds the grid surfaces within the routine to save time otherwise needed to build the grid files. The fewer steps make this routine faster and easier but it doesn't have options for checking surfaces. Instead the input data entities should be checked before running this routine. Also, Calculate Stockpile Volume only applies to volumes calculations when the volume is all Fill.

1. Issue the Surface -- Stockpile/Pond/Pit Volumes -- Calculate Stockpile Volume command. When prompted:
   
   Select stockpile entities and perimeter.
   [FILter]/<Select entities>: type ALL and press Enter (The program looks for a closed 3D polyline on the PERIMETER layer to use as the inclusion perimeter and the base surface model. If this polyline is not found, then the program will prompt to select the perimeter polyline. All the selected entities including the perimeter are used to model the second surface of the stockpile top).
   [FILter]/<Select entities>: press Enter
   The routine offers various reporting capabilities. Let's assume a typical density for a pile of road salt as illustrated below and click OK when ready:
   
   Specify the grid resolution as shown in the dialog below and click OK when ready:
   
   The result is summarized in a volume report in the Standard Report Viewer similar to that shown below:
   
   Click the Exit (Doorway) button to dismiss the report.

NOTE: The limits of the grid are determined automatically and shown in the report. For the sake of accuracy, the next two methods will use the grid parameters shown above.

NOTE: For situations involving a Cut-only scenario (such as a pond or pit), use the Surface -- Stockpile/Pond/Pit Volumes -- Calculate Pond/Pit Volume command.

Volume Method 2 - Volumes By Layers

Let's explore a simple routine that handles both Cut and Fill scenarios.

1. Issue the Surface -- Volumes By Grid Surface -- Volumes By Layers command. When prompted:
   
   Pick Lower Left limit of surface area <8124.32,3995.70>: indicate the values shown to the left and press Enter (or pick a lower left limit)
   Pick Upper Right limit of surface area <8344.32,4177.70>: indicate the values shown to the left and press Enter (or pick an upper right limit)
   Specify the grid resolution as shown in the dialog below and click OK when ready:
   
   A dialog box similar to that shown below appears:
   
   Click the Select Layers from Screen buttons and when prompted:
   
   • Select entities on layers of Existing surface.
     [FILter]/<Select entities>: pick the PERIMETER polyline and press Enter
   • Select entities on layers of Final surface.
     [FILter]/<Select entities>: type ALL and press Enter twice
   Once the values are as shown above, click OK when ready. Prompting resumes:
   Select surface entities on corresponding layers.
   [FILter]/<Select entities>: type ALL and press Enter twice
   Select the Inclusion perimeter polylines or ENTER for none:
   [FILter]/<Select entities>: pick the PERIMETER polyline and press Enter
   [FILter]/<Select entities>: press Enter
   Select the Exclusion perimeter polylines or ENTER for none.
   [FILter]/<Select entities>: press Enter
   Volume Report Options (dialog): set the values as shown below and click OK when ready:
   
   The volume report similar to that shown below appears:
   
   Click the Exit (Doorway) button to dismiss the report.

NOTE: Similar to Calculate Stockpile Volume, this routine builds the grid surfaces within the routine to save the steps of creating grid files. The difference between this routine and the Calculate Stockpile Volume routine is that Volumes By Layers uses entities on specified layers for Existing and Final scenarios to build the surfaces and it will calculate both Cut and Fill volumes.

Volume Method 3 - Two Grid Surface Volumes

For the next example, we must create the two grid files; one representing an assumed base-ground (Existing) surface, the other representing the surface of the pile (Final).

1. Issue the Surface -- Make 3D Grid File command. When prompted:
   
   Grid File to Create (dialog): supply the file name indicated below and click Save when ready:
   
   A dialog box similar to that shown below appears. Set the values as shown and click OK when ready:
   
   Prompting resumes:
   Pick first grid corner <8124.32,3995.70>: press Enter (notice the grid limit from the previous example is defaulted)
   Pick opposite grid corner <8344.32,4177.70>: press Enter
   Select the Inclusion perimeter polylines or ENTER for none.
   [FILter]/<Select entities>: pick the PERIMETER polyline
   [FILter]/<Select entities>: press Enter
   Select the Exclusion perimeter polylines or ENTER for none.
   [FILter]/<Select entities>: press Enter
   Select points, lines, polylines and faces to grid from.
   [FILter]/<Select entities>: pick the PERIMETER polyline again and press Enter
   [FILter]/<Select entities>: press Enter
   
   A grid file representing an assumed base-ground (Existing) surface is written.
2. Re-run the Surface -- Make 3D Grid File command. When prompted:
   
   Grid File to Create (dialog): supply the file name indicated below and click Save when ready:
   
   A dialog box similar to that shown below appears. Set the values as shown and click OK when ready:
   
   NOTE: For the volume routine to follow, the two grids to compare should have matching grid positions and resolution. Prompting resumes:
   Grid File to Get Position From (dialog): select the grid file created earlier and click Open when ready
   Select the Inclusion perimeter polylines or ENTER for none.
   [FILter]/<Select entities>: pick the PERIMETER polyline
   [FILter]/<Select entities>: press Enter
   Select the Exclusion perimeter polylines or ENTER for none.
   [FILter]/<Select entities>: press Enter
   Select points, lines, polylines and faces to grid from.
   [FILter]/<Select entities>: type ALL and press Enter
   [FILter]/<Select entities>: press Enter
   
   A grid file representing the surface of the pile (Final) is written.
3. Optional: Presume we might want to check the surface(s) just created. This step is optional to verify that the surfaces are good by checking for bad elevation data points and that the surfaces follow the data points. Issue the View -- 3D View -- Surface File Viewer and when prompted:
   
   Select Surface File (dialog): select the grid file that was just created and click Open when ready:
   
   A 3D Viewer window similar to that shown below appears:
   
   In the 3D Viewer dialog, move the pointer near the outer edge of the graphic and the cursor will change to an Z symbol which orients the view about the vertical axis. Moving the cursor to the interior of the graphic and the cursor will change to an X/Y symbol. Click and drag from the bottom upward to change the isometric viewing angle. You can also set the Vertical Scale to 2.0 and enable the Color By Elevation toggle for better viewing of the elevation difference. Experiment with any desired remaining options. When ready, click the Exit (Doorway) button.
4. Now, let's check some spot elevations. Issue the Surface -- Surface Inspector command to display a dialog box similar to that shown below:
   
   Use the highlighted controls to set the values as shown above. When ready, click the OK button. As you position the cursor into the data set, notice a real-time reporting of the two surface elevations as illustrated below:
   
   Check that the grid elevations match the point elevations reasonably well. Remember that the base elevations are using only the B-TOE points. The elevations won't match exactly with grid surfaces because the grid model is at the resolution of the grid cells. When finished checking, press Enter.
5. Now that you have the Base and Pile grid files, issue the Surface -- Volumes By Grid Surface -- Two Grid Surface Volumes command. When prompted:
   
   Select the Inclusion perimeter polylines or ENTER for none.
   [FILter]/<Select entities>: pick the PERIMETER polyline
   [FILter]/<Select entities>: press Enter
   Select the Exclusion perimeter polylines or ENTER for none.
   [FILter]/<Select entities>: press Enter
   Select Base Grid File (dialog): select the Base grid file and click Open when ready
   Select Final Grid File (dialog): select the Pile grid file and click Open when ready
   Volume Report Options (dialog): set the values as shown below and click OK when ready:
   
   The volume report similar to that shown below appears:
   
   Click the Exit (Doorway) button to dismiss the report.

NOTE: Although grid files produce relatively accurate volumes (based on the grid resolution), their primary value lies in the ability to hand-calculate the results for validation purposes. With a grid resolution (e.g. 2' x 2') and the average elevation of each grid cell (resulting in a grid depth), a grid cell volume can be computed through traditional means.

Volume Method 4 - Volumes By Triangulation

For precise surface-to-surface volumes, creating triangulated irregular network (TIN) files is the preferred methodology.

1. Issue the Surface -- Triangulate & Contour command. The following dialog box (with several "tabs") will appear which you should fill out as discussed below:
   
   • In the Triangulate tab (as shown above), enable the Write Triangulation File toggle and click its Select button to set the name of a triangulation (*.tin) file as illustrated below. Click the Save button on this dialog box so that the results of the triangulation can be re-used for future purposes. Turn on the Use Inclusion/Exclusion Areas toggle and set any remaining options as illustrated above:
     
   • In the Contour tab, as shown below, toggle off the Draw Contours option:
     
   Click the OK button from any tab. When prompted:
   
   Select Inclusion perimeter polylines or ENTER for none.
   [FILter]/<Select entities>: pick the PERIMETER polyline
   [FILter]/<Select entities>: press Enter
   Select Exclusion perimeter polylines or ENTER for none.
   [FILter]/<Select entities>: press Enter
   Select points and breaklines to Triangulate.
   [FILter]/<Select entities>: pick the PERIMETER polyline again and press Enter
   [FILter]/<Select entities>: press Enter
   
   If a secondary dialog box appears prompting for a coordinate file (*.crd), click Cancel. A "TIN" file representing an assumed base-ground (Existing) surface is written.
2. For the pile TIN, we'll follow the same general procedure as above but with a few small tweaks. Re-issue the Surface -- Triangulate & Contour command and set the values as shown below (click OK when ready):
   
   When prompted:
   
   Select Inclusion perimeter polylines or ENTER for none.
   [FILter]/<Select entities>: pick the PERIMETER polyline
   [FILter]/<Select entities>: press Enter
   Select Exclusion perimeter polylines or ENTER for none.
   [FILter]/<Select entities>: press Enter
   Select points and breaklines to Triangulate.
   [FILter]/<Select entities>: type ALL and press Enter
   [FILter]/<Select entities>: press Enter
   
   If a secondary dialog box appears prompting for a coordinate file (*.crd), click Cancel or select the coordinate file created earlier in this lesson if you so choose and accept the default parameters that follow.
   
   A "TIN" file representing the pile (Final) surface is written.
3. Optional: Similar to the Check Surfaces step under Two Grid Surface Volumes, this is an optional step to check that the surface(s) are correct. Re-issue the View -- 3D View -- Surface File Viewer command and when prompted:
   
   Select Surface File (dialog): select the TIN file that was just created and click Open when ready.
   
   A 3D Viewer window similar to that shown below appears:
   
   When ready, click the Exit (Doorway) button.
4. Now that we have our two triangulation files, we can generate a TIN to TIN prismoidal volume calculation. Of all the volume methods, this one is the most accurate since all the source data points are used in the volume model. Issue the Surface -- Volumes By Triangulation -- Two Triangulation Surface Volumes command. When prompted:
   
   Select EXISTING Surface Triangulation File (dialog): select the Base TIN file and click Open when ready
   Select FINAL Surface Triangulation File (dialog): select the Pile grid file and click Open when ready
   Select Inclusion perimeter polylines or ENTER for none.
   [FILter]/<Select entities>: pick the PERIMETER polyline
   [FILter]/<Select entities>: press Enter
   Select Exclusion perimeter polylines or ENTER for none.
   [FILter]/<Select entities>: press Enter
   Volume Report Options (dialog): set the values as shown below and click OK when ready:
   
   The volume report similar to that shown below appears:
   
   Click the Exit (Doorway) button to dismiss the report.

Volume Method 5 - Calculate Section Volumes

In roadway/corridor types of projects, volumes by Average End Area are commonly used. Let's see the results of this process.

1. Our first task will be to draw a centerline (baseline) upon which the corridor will be based. Issue the Centerline -- Design Centerline command and when prompted:
   
   Centerline File to Design (dialog): set the file name as shown below and click Open when ready
   Design Centerline (dialog): set the values as shown below and click OK when ready
   Pick Point or Point number: type 2016 and press Enter
   Bearing/PI/Exit/Undo/<Pick Point or Point number>: type 2004 and press Enter
   Bearing/PC/PI/Exit/Undo/<Pick Point or Point number>: press Enter
   
   A centerline is generated between the two points.
   
   NOTE: Double-clicking on the polyline on the screen will open the Centerline Editor command.
2. Our next task will be to establish the cross-section limits along this corridor centerline. Issue the Sections -- Section Alignment Editor to display a dialog box similar to that shown below:
   
   Set the file name as indicated above and click Open when ready. When prompted:
   
   Polyline should have been drawn in direction of increasing stations.
   CL File/<Select polyline that represents centerline>: pick the centerline polyline
   Enter Beginning Station of Alignment <0.00>: press Enter
   Section Alignment Settings (dialog): set the values as shown below and click OK when ready
   
   Select boundary polyline: pick the PERIMETER polyline
   
   The program draws temporary lines in the drawing to show the positions of the sections and displays a summary of the section alignment as illustrated below:
   
   Click the Save button followed by the Exit button.
3. To create the section file for the Existing (base) surface, issue the Sections -- Create Sections from... -- Sections from Grid or Triangulation Surface command. When prompted:
   
   Choose Grid or Triangulation file to Process (dialog): specify the base.tin created earlier and click Open when ready
   Section Options (dialog): set the option to Prompt and click OK when ready (with Prompt specified, you'll be prompted if the Section should change if there is an underlying change to the source TIN file)
   Section Alignment File to Process (dialog): specify the section alignment (*.MXS) created earlier and click Open when ready
   Choose Section File to Write (dialog): specify a file name as illustrated below and click Save when ready
   
   
   The first of two section files is written.
4. Let's follow the same general process for the Final (pile) surface with a few minor adjustments. Re-issue the Sections -- Create Sections from... -- Sections from Grid or Triangulation Surface command. When prompted:
   
   Choose Grid or Triangulation file to Process (dialog): specify the pile.tin created earlier and click Open when ready
   Section Options (dialog): set the option to Prompt and click OK when ready
   Section Alignment File to Process (dialog): specify the section alignment (*.MXS) created earlier and click Open when ready
   Choose Section File to Write (dialog): specify a file name as illustrated below and click Save when ready
   
   
   The second of two section files is written.
5. Optional: Similar to the Check Surfaces (grid) and the Check Surfaces (TIN) steps discussed earlier, this is an optional step to check that the section(s) are correct. Issue the Sections -- Section File Editor command and when prompted:
   
   Section File to Process (dialog): select the pile section file that was just created and click Open when ready.
   
   A Section File Editor dialog box similar to that shown below appears:
   
   Set the remaining values as shown above. To examine a specific section, scroll through the list and select a desired station (e.g. 0+70.00) and click the Edit button to display a dialog box similar to that shown below:
   
   Review the controls in this dialog box and click OK when ready and then click Exit on its parent dialog box.
6. Now that we have two section files, we can derive the volume between them. Issue the Sections -- Calculate Section Volumes command. When prompted:
   
   Section File (Existing Ground) to Read (dialog): select the Base section file and click Open when ready
   Section File (Final Ground) to Read (dialog): select the Pile section file and click Open when ready
   Calculate Section Volumes (dialog): set the values as shown below and click OK when ready
   
   The volumes are calculated and reported, along with the cut and fill end-areas at each station as illustrated below:
   
   Review the results and click the Exit (Doorway) button to dismiss the report.

Results Summary

As mentioned earlier, each volume methodology has a particular use and knowing the application(s) for each method will serve you well. Here is a summary of our results:

This completes the tutorial: Calculate Volumes By Five Methods.